From f0b0b420189b0a42abdaac34d51f95ad36fb65da Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bla=C5=BE=20Kristan?= <blaz@kristan-sp.si>
Date: Thu, 8 Jan 2026 20:03:13 +0100
Subject: [PATCH 1/6] Simpler timezones

---
 wled00/data/settings_time.htm |  40 ++---
 wled00/fcn_declare.h          |   1 +
 wled00/ntp.cpp                | 276 ++++++++++++++++++----------------
 wled00/wled.h                 |   4 +
 wled00/xml.cpp                |   1 +
 5 files changed, 161 insertions(+), 161 deletions(-)

diff --git a/wled00/data/settings_time.htm b/wled00/data/settings_time.htm
index 11f3c47d9d..c5cc0c83dc 100644
--- a/wled00/data/settings_time.htm
+++ b/wled00/data/settings_time.htm
@@ -8,6 +8,7 @@
 	<script>
 	var el=false;
 	var ms=["Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"];
+	var zones = ["UTC"];
 	// load common.js with retry on error
 	(function loadFiles() {
 		const l = document.createElement('script');
@@ -23,6 +24,7 @@
 			updLatLon();
 			Cs();
 			FC();
+			TZ();
 		});	// If we set async false, file is loaded and executed, then next statement is processed
 		if (loc) d.Sf.action = getURL('/settings/time');
 	}
@@ -83,6 +85,15 @@
 			}
 		}
 	}
+	function TZ()
+	{
+		zones.forEach((n,i)=>{
+			let o = cE("option");
+			o.value = i++;
+			o.text = n;
+			d.Sf["TZ"].appendChild(o);
+		});
+	}
 	function Wd()
 	{
 		a = [0,0,0,0,0,0,0,0,0,0];
@@ -139,34 +150,7 @@ <h2>Time setup</h2>
 		Get time from NTP server: <input type="checkbox" name="NT"><br>
 		<input type="text" name="NS" maxlength="32"><br>
 		Use 24h format: <input type="checkbox" name="CF"><br>
-		Time zone: 
-		<select name="TZ">
-			<option value="0" selected>GMT(UTC)</option>
-			<option value="1">GMT/BST</option>
-			<option value="2">CET/CEST</option>
-			<option value="3">EET/EEST</option>
-			<option value="4">US-EST/EDT</option>
-			<option value="5">US-CST/CDT</option>
-			<option value="6">US-MST/MDT</option>
-			<option value="7">US-AZ</option>
-			<option value="8">US-PST/PDT</option>
-			<option value="9">CST (AWST, PHST)</option>
-			<option value="10">JST (KST)</option>
-			<option value="11">AEST/AEDT</option>
-			<option value="12">NZST/NZDT</option>
-			<option value="13">North Korea</option>
-			<option value="14">IST (India)</option>
-			<option value="15">CA-Saskatchewan</option>
-			<option value="16">ACST</option>
-			<option value="17">ACST/ACDT</option>
-			<option value="18">HST (Hawaii)</option>
-			<option value="19">NOVT (Novosibirsk)</option>
-			<option value="20">AKST/AKDT (Anchorage)</option>
-			<option value="21">MX-CST</option>
-			<option value="22">PKT (Pakistan)</option>
-			<option value="23">BRT (Brasília)</option>
-			<option value="24">AWST (Perth)</option>
-		</select><br>
+		Time zone: <select name="TZ"></select><br>
 		UTC offset: <input name="UO" type="number" min="-65500" max="65500" required> seconds (max. 18 hours)<br>
 		Current local time is <span class="times">unknown</span>.<br>
 		Latitude: <select name="LTR"><option value="N">N</option><option value="S">S</option></select><input name="LT" type="number" class="xl" min="0" max="66.6" step="0.01"><br>
diff --git a/wled00/fcn_declare.h b/wled00/fcn_declare.h
index 4bbedfacb0..ede6377256 100644
--- a/wled00/fcn_declare.h
+++ b/wled00/fcn_declare.h
@@ -191,6 +191,7 @@ bool initMqtt();
 void publishMqtt();
 
 //ntp.cpp
+String getTZNamesJSONString();
 void handleTime();
 void handleNetworkTime();
 void sendNTPPacket();
diff --git a/wled00/ntp.cpp b/wled00/ntp.cpp
index abad5c3c9d..a6e015a9d7 100644
--- a/wled00/ntp.cpp
+++ b/wled00/ntp.cpp
@@ -13,155 +13,165 @@
 
 Timezone* tz;
 
-#define TZ_UTC                  0
-#define TZ_UK                   1
-#define TZ_EUROPE_CENTRAL       2
-#define TZ_EUROPE_EASTERN       3
-#define TZ_US_EASTERN           4
-#define TZ_US_CENTRAL           5
-#define TZ_US_MOUNTAIN          6
-#define TZ_US_ARIZONA           7
-#define TZ_US_PACIFIC           8
-#define TZ_CHINA                9
-#define TZ_JAPAN               10
-#define TZ_AUSTRALIA_EASTERN   11
-#define TZ_NEW_ZEALAND         12
-#define TZ_NORTH_KOREA         13
-#define TZ_INDIA               14
-#define TZ_SASKACHEWAN         15
-#define TZ_AUSTRALIA_NORTHERN  16
-#define TZ_AUSTRALIA_SOUTHERN  17
-#define TZ_HAWAII              18
-#define TZ_NOVOSIBIRSK         19
-#define TZ_ANCHORAGE           20
-#define TZ_MX_CENTRAL          21
-#define TZ_PAKISTAN            22
-#define TZ_BRASILIA            23
-#define TZ_AUSTRALIA_WESTERN   24
-
-#define TZ_COUNT               25
-#define TZ_INIT               255
-
+#define TZ_INIT 255
 byte tzCurrent = TZ_INIT; //uninitialized
 
 /* C++11 form -- static std::array<std::pair<TimeChangeRule, TimeChangeRule>, TZ_COUNT> TZ_TABLE PROGMEM = {{ */
-static const std::pair<TimeChangeRule, TimeChangeRule> TZ_TABLE[] PROGMEM = {
-    /* TZ_UTC */ {
-      {Last, Sun, Mar, 1, 0}, // UTC
-      {Last, Sun, Mar, 1, 0}  // Same
-    },
-    /* TZ_UK */ {
-      {Last, Sun, Mar, 1, 60},      //British Summer Time
-      {Last, Sun, Oct, 2, 0}       //Standard Time
-    },
-    /* TZ_EUROPE_CENTRAL */ {
-      {Last, Sun, Mar, 2, 120},     //Central European Summer Time
-      {Last, Sun, Oct, 3, 60}      //Central European Standard Time
-    },
-    /* TZ_EUROPE_EASTERN */ {
-      {Last, Sun, Mar, 3, 180},     //East European Summer Time
-      {Last, Sun, Oct, 4, 120}     //East European Standard Time
-    },
-    /* TZ_US_EASTERN */ {
-      {Second, Sun, Mar, 2, -240},  //EDT = UTC - 4 hours
-      {First,  Sun, Nov, 2, -300}  //EST = UTC - 5 hours
-    },
-    /* TZ_US_CENTRAL */ {
-      {Second, Sun, Mar, 2, -300},  //CDT = UTC - 5 hours
-      {First,  Sun, Nov, 2, -360}  //CST = UTC - 6 hours
-    },
-    /* TZ_US_MOUNTAIN */ {
-      {Second, Sun, Mar, 2, -360},  //MDT = UTC - 6 hours
-      {First,  Sun, Nov, 2, -420}  //MST = UTC - 7 hours
-    },
-    /* TZ_US_ARIZONA */ {
-      {First,  Sun, Nov, 2, -420},  //MST = UTC - 7 hours
-      {First,  Sun, Nov, 2, -420}  //MST = UTC - 7 hours
-    },
-    /* TZ_US_PACIFIC */ {
-      {Second, Sun, Mar, 2, -420},  //PDT = UTC - 7 hours
-      {First,  Sun, Nov, 2, -480}  //PST = UTC - 8 hours
-    },
-    /* TZ_CHINA */ {
-      {Last, Sun, Mar, 1, 480},     //CST = UTC + 8 hours
-      {Last, Sun, Mar, 1, 480}
-    },
-    /* TZ_JAPAN */ {
-      {Last, Sun, Mar, 1, 540},     //JST = UTC + 9 hours
-      {Last, Sun, Mar, 1, 540}
-    },
-    /* TZ_AUSTRALIA_EASTERN */ {
-      {First,  Sun, Oct, 2, 660},   //AEDT = UTC + 11 hours
-      {First,  Sun, Apr, 3, 600}   //AEST = UTC + 10 hours
-    },
-    /* TZ_NEW_ZEALAND */ {
-      {Last,   Sun, Sep, 2, 780},   //NZDT = UTC + 13 hours
-      {First,  Sun, Apr, 3, 720}   //NZST = UTC + 12 hours
-    },
-    /* TZ_NORTH_KOREA */ {
-      {Last, Sun, Mar, 1, 510},     //Pyongyang Time = UTC + 8.5 hours
-      {Last, Sun, Mar, 1, 510}
-    },
-    /* TZ_INDIA */ {
-      {Last, Sun, Mar, 1, 330},     //India Standard Time = UTC + 5.5 hours
-      {Last, Sun, Mar, 1, 330}
-    },
-    /* TZ_SASKACHEWAN */ {
-      {First,  Sun, Nov, 2, -360},  //CST = UTC - 6 hours
-      {First,  Sun, Nov, 2, -360}
-    },
-    /* TZ_AUSTRALIA_NORTHERN */ {
-      {First, Sun, Apr, 3, 570},   //ACST = UTC + 9.5 hours
-      {First, Sun, Apr, 3, 570}
-    },
-    /* TZ_AUSTRALIA_SOUTHERN */ {
-      {First, Sun, Oct, 2, 630},   //ACDT = UTC + 10.5 hours
-      {First, Sun, Apr, 3, 570}   //ACST = UTC + 9.5 hours
-    },
-    /* TZ_HAWAII */ {
-      {Last, Sun, Mar, 1, -600},   //HST =  UTC - 10 hours
-      {Last, Sun, Mar, 1, -600}
-    },
-    /* TZ_NOVOSIBIRSK */ {
-      {Last, Sun, Mar, 1, 420},     //CST = UTC + 7 hours
-      {Last, Sun, Mar, 1, 420}
-    },
-    /* TZ_ANCHORAGE */ {
-      {Second, Sun, Mar, 2, -480},  //AKDT = UTC - 8 hours
-      {First, Sun, Nov, 2, -540}   //AKST = UTC - 9 hours
-    },
-     /* TZ_MX_CENTRAL */ {
-      {First, Sun, Apr, 2, -360},  //CST = UTC - 6 hours
-      {First, Sun, Apr, 2, -360}
-    },
-    /* TZ_PAKISTAN */ {
-      {Last, Sun, Mar, 1, 300},     //Pakistan Standard Time = UTC + 5 hours
-      {Last, Sun, Mar, 1, 300}
-    },
-    /* TZ_BRASILIA */ {
-      {Last, Sun, Mar, 1, -180},    //Brasília Standard Time = UTC - 3 hours
-      {Last, Sun, Mar, 1, -180}
-    },
-    /* TZ_AUSTRALIA_WESTERN */ {
-      {Last, Sun, Mar, 1, 480},     //AWST = UTC + 8 hours
-      {Last, Sun, Mar, 1, 480}      //AWST = UTC + 8 hours (no DST)
-    }
+static const std::tuple<const char*, TimeChangeRule, TimeChangeRule> TZ_TABLE[] PROGMEM = {
+  /* TZ_UTC */ {
+    "UTC",
+    {Last, Sun, Mar, 1, 0}, // UTC
+    {Last, Sun, Mar, 1, 0}  // Same
+  },
+  /* TZ_UK */ {
+    "GMT/BST",
+    {Last, Sun, Mar, 1, 60},      //British Summer Time
+    {Last, Sun, Oct, 2, 0}       //Standard Time
+  },
+  /* TZ_EUROPE_CENTRAL */ {
+    "CET/CEST",
+    {Last, Sun, Mar, 2, 120},     //Central European Summer Time
+    {Last, Sun, Oct, 3, 60}      //Central European Standard Time
+  },
+  /* TZ_EUROPE_EASTERN */ {
+    "EET/EEST",
+    {Last, Sun, Mar, 3, 180},     //East European Summer Time
+    {Last, Sun, Oct, 4, 120}     //East European Standard Time
+  },
+  /* TZ_US_EASTERN */ {
+    "US-EST/EDT",
+    {Second, Sun, Mar, 2, -240},  //EDT = UTC - 4 hours
+    {First,  Sun, Nov, 2, -300}  //EST = UTC - 5 hours
+  },
+  /* TZ_US_CENTRAL */ {
+    "US-CST/CDT",
+    {Second, Sun, Mar, 2, -300},  //CDT = UTC - 5 hours
+    {First,  Sun, Nov, 2, -360}  //CST = UTC - 6 hours
+  },
+  /* TZ_US_MOUNTAIN */ {
+    "US-MST/MDT",
+    {Second, Sun, Mar, 2, -360},  //MDT = UTC - 6 hours
+    {First,  Sun, Nov, 2, -420}  //MST = UTC - 7 hours
+  },
+  /* TZ_US_ARIZONA */ {
+    "US-AZ",
+    {First,  Sun, Nov, 2, -420},  //MST = UTC - 7 hours
+    {First,  Sun, Nov, 2, -420}  //MST = UTC - 7 hours
+  },
+  /* TZ_US_PACIFIC */ {
+    "US-PST/PDT",
+    {Second, Sun, Mar, 2, -420},  //PDT = UTC - 7 hours
+    {First,  Sun, Nov, 2, -480}  //PST = UTC - 8 hours
+  },
+  /* TZ_CHINA */ {
+    "CST (AWST, PHST)",
+    {Last, Sun, Mar, 1, 480},     //CST = UTC + 8 hours
+    {Last, Sun, Mar, 1, 480}
+  },
+  /* TZ_JAPAN */ {
+    "JST (KST)",
+    {Last, Sun, Mar, 1, 540},     //JST = UTC + 9 hours
+    {Last, Sun, Mar, 1, 540}
+  },
+  /* TZ_AUSTRALIA_EASTERN */ {
+    "AEST/AEDT",
+    {First,  Sun, Oct, 2, 660},   //AEDT = UTC + 11 hours
+    {First,  Sun, Apr, 3, 600}   //AEST = UTC + 10 hours
+  },
+  /* TZ_NEW_ZEALAND */ {
+    "NZST/NZDT",
+    {Last,   Sun, Sep, 2, 780},   //NZDT = UTC + 13 hours
+    {First,  Sun, Apr, 3, 720}   //NZST = UTC + 12 hours
+  },
+  /* TZ_NORTH_KOREA */ {
+    "North Korea",
+    {Last, Sun, Mar, 1, 510},     //Pyongyang Time = UTC + 8.5 hours
+    {Last, Sun, Mar, 1, 510}
+  },
+  /* TZ_INDIA */ {
+    "IST (India)",
+    {Last, Sun, Mar, 1, 330},     //India Standard Time = UTC + 5.5 hours
+    {Last, Sun, Mar, 1, 330}
+  },
+  /* TZ_SASKACHEWAN */ {
+    "CA-Saskatchewan",
+    {First,  Sun, Nov, 2, -360},  //CST = UTC - 6 hours
+    {First,  Sun, Nov, 2, -360}
+  },
+  /* TZ_AUSTRALIA_NORTHERN */ {
+    "ACST",
+    {First, Sun, Apr, 3, 570},   //ACST = UTC + 9.5 hours
+    {First, Sun, Apr, 3, 570}
+  },
+  /* TZ_AUSTRALIA_SOUTHERN */ {
+    "ACST/ACDT",
+    {First, Sun, Oct, 2, 630},   //ACDT = UTC + 10.5 hours
+    {First, Sun, Apr, 3, 570}   //ACST = UTC + 9.5 hours
+  },
+  /* TZ_HAWAII */ {
+    "HST (Hawaii)",
+    {Last, Sun, Mar, 1, -600},   //HST =  UTC - 10 hours
+    {Last, Sun, Mar, 1, -600}
+  },
+  /* TZ_NOVOSIBIRSK */ {
+    "NOVT (Novosibirsk)",
+    {Last, Sun, Mar, 1, 420},     //CST = UTC + 7 hours
+    {Last, Sun, Mar, 1, 420}
+  },
+  /* TZ_ANCHORAGE */ {
+    "AKST/AKDT (Anchorage)",
+    {Second, Sun, Mar, 2, -480},  //AKDT = UTC - 8 hours
+    {First, Sun, Nov, 2, -540}   //AKST = UTC - 9 hours
+  },
+    /* TZ_MX_CENTRAL */ {
+    "MX-CST",
+    {First, Sun, Apr, 2, -360},  //CST = UTC - 6 hours
+    {First, Sun, Apr, 2, -360}
+  },
+  /* TZ_PAKISTAN */ {
+    "PKT (Pakistan)",
+    {Last, Sun, Mar, 1, 300},     //Pakistan Standard Time = UTC + 5 hours
+    {Last, Sun, Mar, 1, 300}
+  },
+  /* TZ_BRASILIA */ {
+    "BRT (Brasília)",
+    {Last, Sun, Mar, 1, -180},    //Brasília Standard Time = UTC - 3 hours
+    {Last, Sun, Mar, 1, -180}
+  },
+  /* TZ_AUSTRALIA_WESTERN */ {
+    "AWST (Perth)",
+    {Last, Sun, Mar, 1, 480},     //AWST = UTC + 8 hours
+    {Last, Sun, Mar, 1, 480}      //AWST = UTC + 8 hours (no DST)
+  }
 };
 
+
 void updateTimezone() {
   delete tz;
   TimeChangeRule tcrDaylight, tcrStandard;
   auto tz_table_entry = currentTimezone;
-  if (tz_table_entry >= TZ_COUNT) {
+  if (tz_table_entry >= countof(TZ_TABLE)) {
     tz_table_entry = 0;
   }
   tzCurrent = currentTimezone;
-  memcpy_P(&tcrDaylight, &TZ_TABLE[tz_table_entry].first, sizeof(tcrDaylight));
-  memcpy_P(&tcrStandard, &TZ_TABLE[tz_table_entry].second, sizeof(tcrStandard));
+  memcpy_P(&tcrDaylight, &std::get<1>(TZ_TABLE[tz_table_entry]), sizeof(tcrDaylight));
+  memcpy_P(&tcrStandard, &std::get<2>(TZ_TABLE[tz_table_entry]), sizeof(tcrStandard));
 
   tz = new Timezone(tcrDaylight, tcrStandard);
 }
 
+String getTZNamesJSONString() {
+  String names = "[";
+  for (size_t i = 0; i < countof(TZ_TABLE); i++) {
+    names += '"';
+    names += FPSTR(std::get<0>(TZ_TABLE[i]));
+    names += '"';
+    names += ',';
+  }
+  names.setCharAt(names.length()-1, ']'); // replace last comma with bracket
+  return names;
+}
+
 void handleTime() {
   handleNetworkTime();
 
diff --git a/wled00/wled.h b/wled00/wled.h
index 66b33740d6..9e48abeddd 100644
--- a/wled00/wled.h
+++ b/wled00/wled.h
@@ -270,6 +270,10 @@ using PSRAMDynamicJsonDocument = BasicJsonDocument<PSRAM_Allocator>;
 
 #define STRINGIFY(X) #X
 #define TOSTRING(X) STRINGIFY(X)
+#ifdef countof
+  #undef countof
+#endif
+#define countof(x) (sizeof(x)/sizeof(x[0]))
 
 #define WLED_CODENAME "Niji"
 
diff --git a/wled00/xml.cpp b/wled00/xml.cpp
index 194256d82e..e7eb38aa09 100644
--- a/wled00/xml.cpp
+++ b/wled00/xml.cpp
@@ -544,6 +544,7 @@ void getSettingsJS(byte subPage, Print& settingsScript)
 
   if (subPage == SUBPAGE_TIME)
   {
+    settingsScript.printf_P(PSTR("zones=%s;"), getTZNamesJSONString().c_str());
     printSetFormCheckbox(settingsScript,PSTR("NT"),ntpEnabled);
     printSetFormValue(settingsScript,PSTR("NS"),ntpServerName);
     printSetFormCheckbox(settingsScript,PSTR("CF"),!useAMPM);

From 06c9ff881d7d19347adf8d23e0263998d345e162 Mon Sep 17 00:00:00 2001
From: Blaz Kristan <blaz@kristan-sp.si>
Date: Sat, 10 Jan 2026 13:47:00 +0100
Subject: [PATCH 2/6] Try to put strings into PROGMEM

---
 wled00/ntp.cpp | 131 +++++++++++++++++++++++++++++--------------------
 1 file changed, 79 insertions(+), 52 deletions(-)

diff --git a/wled00/ntp.cpp b/wled00/ntp.cpp
index a6e015a9d7..8c64234de2 100644
--- a/wled00/ntp.cpp
+++ b/wled00/ntp.cpp
@@ -16,130 +16,156 @@ Timezone* tz;
 #define TZ_INIT 255
 byte tzCurrent = TZ_INIT; //uninitialized
 
-/* C++11 form -- static std::array<std::pair<TimeChangeRule, TimeChangeRule>, TZ_COUNT> TZ_TABLE PROGMEM = {{ */
-static const std::tuple<const char*, TimeChangeRule, TimeChangeRule> TZ_TABLE[] PROGMEM = {
-  /* TZ_UTC */ {
-    "UTC",
+// workaround to put all strings into PROGMEM
+static const char _utc[]    PROGMEM = "UTC";
+static const char _gmt[]    PROGMEM = "GMT/BST";
+static const char _cet[]    PROGMEM = "CET/CEST";
+static const char _eet[]    PROGMEM = "EET/EEST";
+static const char _us_est[] PROGMEM = "US-EST/EDT";
+static const char _us_cst[] PROGMEM = "US-CST/CDT";
+static const char _us_mst[] PROGMEM = "US-MST/MDT";
+static const char _us_az[]  PROGMEM = "US-AZ";
+static const char _us_pst[] PROGMEM = "US-PST/PDT";
+static const char _cst[]    PROGMEM = "CST (AWST, PHST)";
+static const char _jst[]    PROGMEM = "JST (KST)";
+static const char _aest[]   PROGMEM = "AEST/AEDT";
+static const char _nzst[]   PROGMEM = "NZST/NZDT";
+static const char _nkst[]   PROGMEM = "North Korea";
+static const char _ist[]    PROGMEM = "IST (India)";
+static const char _ca_sk[]  PROGMEM = "CA-Saskatchewan";
+static const char _acst[]   PROGMEM = "ACST";
+static const char _acst2[]  PROGMEM = "ACST/ACDT";
+static const char _hst[]    PROGMEM = "HST (Hawaii)";
+static const char _novt[]   PROGMEM = "NOVT (Novosibirsk)";
+static const char _akst[]   PROGMEM = "AKST/AKDT (Anchorage)";
+static const char _mxcst[]  PROGMEM = "MX-CST";
+static const char _pkt[]    PROGMEM = "PKT (Pakistan)";
+static const char _brt[]    PROGMEM = "BRT (Brasília)";
+static const char _awst[]   PROGMEM = "AWST (Perth)";
+
+static const std::tuple<const char*, const TimeChangeRule, const TimeChangeRule> TZ_TABLE[] PROGMEM = {
+  {
+    _utc,
     {Last, Sun, Mar, 1, 0}, // UTC
     {Last, Sun, Mar, 1, 0}  // Same
   },
-  /* TZ_UK */ {
-    "GMT/BST",
+  {
+    _gmt,
     {Last, Sun, Mar, 1, 60},      //British Summer Time
     {Last, Sun, Oct, 2, 0}       //Standard Time
   },
-  /* TZ_EUROPE_CENTRAL */ {
-    "CET/CEST",
+  {
+    _cet,
     {Last, Sun, Mar, 2, 120},     //Central European Summer Time
     {Last, Sun, Oct, 3, 60}      //Central European Standard Time
   },
-  /* TZ_EUROPE_EASTERN */ {
-    "EET/EEST",
+  {
+    _eet,
     {Last, Sun, Mar, 3, 180},     //East European Summer Time
     {Last, Sun, Oct, 4, 120}     //East European Standard Time
   },
-  /* TZ_US_EASTERN */ {
-    "US-EST/EDT",
+  {
+    _us_est,
     {Second, Sun, Mar, 2, -240},  //EDT = UTC - 4 hours
     {First,  Sun, Nov, 2, -300}  //EST = UTC - 5 hours
   },
-  /* TZ_US_CENTRAL */ {
-    "US-CST/CDT",
+  {
+    _us_cst,
     {Second, Sun, Mar, 2, -300},  //CDT = UTC - 5 hours
     {First,  Sun, Nov, 2, -360}  //CST = UTC - 6 hours
   },
-  /* TZ_US_MOUNTAIN */ {
-    "US-MST/MDT",
+  {
+    _us_mst,
     {Second, Sun, Mar, 2, -360},  //MDT = UTC - 6 hours
     {First,  Sun, Nov, 2, -420}  //MST = UTC - 7 hours
   },
-  /* TZ_US_ARIZONA */ {
-    "US-AZ",
+  {
+    _us_az,
     {First,  Sun, Nov, 2, -420},  //MST = UTC - 7 hours
     {First,  Sun, Nov, 2, -420}  //MST = UTC - 7 hours
   },
-  /* TZ_US_PACIFIC */ {
-    "US-PST/PDT",
+  {
+    _us_pst,
     {Second, Sun, Mar, 2, -420},  //PDT = UTC - 7 hours
     {First,  Sun, Nov, 2, -480}  //PST = UTC - 8 hours
   },
-  /* TZ_CHINA */ {
-    "CST (AWST, PHST)",
+  {
+    _cst,
     {Last, Sun, Mar, 1, 480},     //CST = UTC + 8 hours
     {Last, Sun, Mar, 1, 480}
   },
-  /* TZ_JAPAN */ {
-    "JST (KST)",
+  {
+    _jst,
     {Last, Sun, Mar, 1, 540},     //JST = UTC + 9 hours
     {Last, Sun, Mar, 1, 540}
   },
-  /* TZ_AUSTRALIA_EASTERN */ {
-    "AEST/AEDT",
+  {
+    _aest,
     {First,  Sun, Oct, 2, 660},   //AEDT = UTC + 11 hours
     {First,  Sun, Apr, 3, 600}   //AEST = UTC + 10 hours
   },
-  /* TZ_NEW_ZEALAND */ {
-    "NZST/NZDT",
+  {
+    _nzst,
     {Last,   Sun, Sep, 2, 780},   //NZDT = UTC + 13 hours
     {First,  Sun, Apr, 3, 720}   //NZST = UTC + 12 hours
   },
-  /* TZ_NORTH_KOREA */ {
-    "North Korea",
+  {
+    _nkst,
     {Last, Sun, Mar, 1, 510},     //Pyongyang Time = UTC + 8.5 hours
     {Last, Sun, Mar, 1, 510}
   },
-  /* TZ_INDIA */ {
-    "IST (India)",
+  {
+    _ist,
     {Last, Sun, Mar, 1, 330},     //India Standard Time = UTC + 5.5 hours
     {Last, Sun, Mar, 1, 330}
   },
-  /* TZ_SASKACHEWAN */ {
-    "CA-Saskatchewan",
+  {
+    _ca_sk,
     {First,  Sun, Nov, 2, -360},  //CST = UTC - 6 hours
     {First,  Sun, Nov, 2, -360}
   },
-  /* TZ_AUSTRALIA_NORTHERN */ {
-    "ACST",
+  {
+    _acst,
     {First, Sun, Apr, 3, 570},   //ACST = UTC + 9.5 hours
     {First, Sun, Apr, 3, 570}
   },
-  /* TZ_AUSTRALIA_SOUTHERN */ {
-    "ACST/ACDT",
+  {
+    _acst2,
     {First, Sun, Oct, 2, 630},   //ACDT = UTC + 10.5 hours
     {First, Sun, Apr, 3, 570}   //ACST = UTC + 9.5 hours
   },
-  /* TZ_HAWAII */ {
-    "HST (Hawaii)",
+  {
+    _hst,
     {Last, Sun, Mar, 1, -600},   //HST =  UTC - 10 hours
     {Last, Sun, Mar, 1, -600}
   },
-  /* TZ_NOVOSIBIRSK */ {
-    "NOVT (Novosibirsk)",
+  {
+    _novt,
     {Last, Sun, Mar, 1, 420},     //CST = UTC + 7 hours
     {Last, Sun, Mar, 1, 420}
   },
-  /* TZ_ANCHORAGE */ {
-    "AKST/AKDT (Anchorage)",
+  {
+    _akst,
     {Second, Sun, Mar, 2, -480},  //AKDT = UTC - 8 hours
     {First, Sun, Nov, 2, -540}   //AKST = UTC - 9 hours
   },
-    /* TZ_MX_CENTRAL */ {
-    "MX-CST",
+  {
+    _mxcst,
     {First, Sun, Apr, 2, -360},  //CST = UTC - 6 hours
     {First, Sun, Apr, 2, -360}
   },
-  /* TZ_PAKISTAN */ {
-    "PKT (Pakistan)",
+  {
+    _pkt,
     {Last, Sun, Mar, 1, 300},     //Pakistan Standard Time = UTC + 5 hours
     {Last, Sun, Mar, 1, 300}
   },
-  /* TZ_BRASILIA */ {
-    "BRT (Brasília)",
+  {
+    _brt,
     {Last, Sun, Mar, 1, -180},    //Brasília Standard Time = UTC - 3 hours
     {Last, Sun, Mar, 1, -180}
   },
-  /* TZ_AUSTRALIA_WESTERN */ {
-    "AWST (Perth)",
+  {
+    _awst,
     {Last, Sun, Mar, 1, 480},     //AWST = UTC + 8 hours
     {Last, Sun, Mar, 1, 480}      //AWST = UTC + 8 hours (no DST)
   }
@@ -163,6 +189,7 @@ void updateTimezone() {
 String getTZNamesJSONString() {
   String names = "[";
   for (size_t i = 0; i < countof(TZ_TABLE); i++) {
+    // the following is shorter code than sprintf()
     names += '"';
     names += FPSTR(std::get<0>(TZ_TABLE[i]));
     names += '"';

From ee7964e5f52b327f50dc6a5b15297f0e6ea169a6 Mon Sep 17 00:00:00 2001
From: Blaz Kristan <blaz@kristan-sp.si>
Date: Sat, 10 Jan 2026 20:27:48 +0100
Subject: [PATCH 3/6] Bugfix for too late select box population

---
 wled00/data/settings_time.htm | 1 -
 wled00/xml.cpp                | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/wled00/data/settings_time.htm b/wled00/data/settings_time.htm
index c5cc0c83dc..49563930d6 100644
--- a/wled00/data/settings_time.htm
+++ b/wled00/data/settings_time.htm
@@ -24,7 +24,6 @@
 			updLatLon();
 			Cs();
 			FC();
-			TZ();
 		});	// If we set async false, file is loaded and executed, then next statement is processed
 		if (loc) d.Sf.action = getURL('/settings/time');
 	}
diff --git a/wled00/xml.cpp b/wled00/xml.cpp
index e7eb38aa09..cf14077468 100644
--- a/wled00/xml.cpp
+++ b/wled00/xml.cpp
@@ -544,7 +544,7 @@ void getSettingsJS(byte subPage, Print& settingsScript)
 
   if (subPage == SUBPAGE_TIME)
   {
-    settingsScript.printf_P(PSTR("zones=%s;"), getTZNamesJSONString().c_str());
+    settingsScript.printf_P(PSTR("zones=%s;TZ();"), getTZNamesJSONString().c_str()); // we must fill select box immediately after populating array
     printSetFormCheckbox(settingsScript,PSTR("NT"),ntpEnabled);
     printSetFormValue(settingsScript,PSTR("NS"),ntpServerName);
     printSetFormCheckbox(settingsScript,PSTR("CF"),!useAMPM);

From 324c24f172c92aff1c13c59185cb61dd7c75f48b Mon Sep 17 00:00:00 2001
From: Blaz Kristan <blaz@kristan-sp.si>
Date: Sat, 10 Jan 2026 20:40:08 +0100
Subject: [PATCH 4/6] Implement rabbit's suggestions

---
 wled00/data/settings_time.htm | 2 +-
 wled00/ntp.cpp                | 7 ++++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/wled00/data/settings_time.htm b/wled00/data/settings_time.htm
index 49563930d6..084407e3bf 100644
--- a/wled00/data/settings_time.htm
+++ b/wled00/data/settings_time.htm
@@ -88,7 +88,7 @@
 	{
 		zones.forEach((n,i)=>{
 			let o = cE("option");
-			o.value = i++;
+			o.value = i;
 			o.text = n;
 			d.Sf["TZ"].appendChild(o);
 		});
diff --git a/wled00/ntp.cpp b/wled00/ntp.cpp
index 8c64234de2..dd7cd462ac 100644
--- a/wled00/ntp.cpp
+++ b/wled00/ntp.cpp
@@ -188,6 +188,7 @@ void updateTimezone() {
 
 String getTZNamesJSONString() {
   String names = "[";
+  name.reserve(512);
   for (size_t i = 0; i < countof(TZ_TABLE); i++) {
     // the following is shorter code than sprintf()
     names += '"';
@@ -273,7 +274,7 @@ static bool isValidNtpResponse(const byte* ntpPacket) {
   // if((ntpPacket[0] & 0b00111000) >> 3 < 0b100) return false; //reject Version < 4
   if((ntpPacket[0] & 0b00000111) != 0b100)      return false; //reject Mode != Server
   if((ntpPacket[1] < 1) || (ntpPacket[1] > 15)) return false; //reject invalid Stratum
-  if( ntpPacket[16] == 0 && ntpPacket[17] == 0 && 
+  if( ntpPacket[16] == 0 && ntpPacket[17] == 0 &&
       ntpPacket[18] == 0 && ntpPacket[19] == 0 &&
       ntpPacket[20] == 0 && ntpPacket[21] == 0 &&
       ntpPacket[22] == 0 && ntpPacket[23] == 0)               //reject ReferenceTimestamp == 0
@@ -520,7 +521,7 @@ static int getSunriseUTC(int year, int month, int day, float lat, float lon, boo
 	return UT*60;
 }
 
-#define SUNSET_MAX (24*60) // 1day = max expected absolute value for sun offset in minutes 
+#define SUNSET_MAX (24*60) // 1day = max expected absolute value for sun offset in minutes
 // calculate sunrise and sunset (if longitude and latitude are set)
 void calculateSunriseAndSunset() {
   if ((int)(longitude*10.) || (int)(latitude*10.)) {
@@ -589,4 +590,4 @@ void setTimeFromAPI(uint32_t timein) {
     calculateSunriseAndSunset();
   }
   if (presetsModifiedTime == 0) presetsModifiedTime = timein;
-}
\ No newline at end of file
+}

From d1cef9c5cd82b7bb4f2ab76fb301ce64c4f2d58a Mon Sep 17 00:00:00 2001
From: Blaz Kristan <blaz@kristan-sp.si>
Date: Sat, 10 Jan 2026 20:44:44 +0100
Subject: [PATCH 5/6] Fixing typo

---
 wled00/ntp.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/wled00/ntp.cpp b/wled00/ntp.cpp
index dd7cd462ac..2aeb97dab2 100644
--- a/wled00/ntp.cpp
+++ b/wled00/ntp.cpp
@@ -188,7 +188,7 @@ void updateTimezone() {
 
 String getTZNamesJSONString() {
   String names = "[";
-  name.reserve(512);
+  names.reserve(512);
   for (size_t i = 0; i < countof(TZ_TABLE); i++) {
     // the following is shorter code than sprintf()
     names += '"';

From 55601d0cf1d9982d70698c559be77c135e9db12b Mon Sep 17 00:00:00 2001
From: Blaz Kristan <blaz@kristan-sp.si>
Date: Tue, 13 Jan 2026 19:53:33 +0100
Subject: [PATCH 6/6] Address raised issues

---
 wled00/ntp.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/wled00/ntp.cpp b/wled00/ntp.cpp
index 2aeb97dab2..3482c7e87e 100644
--- a/wled00/ntp.cpp
+++ b/wled00/ntp.cpp
@@ -43,6 +43,8 @@ static const char _pkt[]    PROGMEM = "PKT (Pakistan)";
 static const char _brt[]    PROGMEM = "BRT (Brasília)";
 static const char _awst[]   PROGMEM = "AWST (Perth)";
 
+// WARNING: Changing the order of entries in this table will change the meaning of stored timezone indices in settings!
+// Add new timezones only at the end of the list to preserve compatibility!
 static const std::tuple<const char*, const TimeChangeRule, const TimeChangeRule> TZ_TABLE[] PROGMEM = {
   {
     _utc,
@@ -179,7 +181,7 @@ void updateTimezone() {
   if (tz_table_entry >= countof(TZ_TABLE)) {
     tz_table_entry = 0;
   }
-  tzCurrent = currentTimezone;
+  tzCurrent = currentTimezone = tz_table_entry;
   memcpy_P(&tcrDaylight, &std::get<1>(TZ_TABLE[tz_table_entry]), sizeof(tcrDaylight));
   memcpy_P(&tcrStandard, &std::get<2>(TZ_TABLE[tz_table_entry]), sizeof(tcrStandard));