diff --git a/draftlogs/7456_fix.md b/draftlogs/7456_fix.md
new file mode 100644
index 00000000000..587a23d9995
--- /dev/null
+++ b/draftlogs/7456_fix.md
@@ -0,0 +1 @@
+ - Fix Persian calendar leap year [[#7456](https://github.com/plotly/plotly.js/pull/7456)]
diff --git a/package-lock.json b/package-lock.json
index 4062c814583..ed644ff0e06 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -58,7 +58,7 @@
         "to-px": "1.0.1",
         "topojson-client": "^3.1.0",
         "webgl-context": "^2.2.0",
-        "world-calendars": "^1.0.3"
+        "world-calendars": "github:archmoj/world-calendars#0faeec8544d289c94845a73fcbb813b9bb423599"
       },
       "devDependencies": {
         "@biomejs/biome": "1.8.3",
@@ -10909,8 +10909,9 @@
     },
     "node_modules/world-calendars": {
       "version": "1.0.3",
-      "resolved": "https://registry.npmjs.org/world-calendars/-/world-calendars-1.0.3.tgz",
-      "integrity": "sha1-slxQMrokEo/8QdCfr0pewbnBQzU=",
+      "resolved": "git+ssh://git@github.com/archmoj/world-calendars.git#0faeec8544d289c94845a73fcbb813b9bb423599",
+      "integrity": "sha512-fzQ4K3LOfHT8RBu1dj608UTIrorwDXXhJLqArqdZstHyurcOipgI2/EkJYO27jDDNUe0vRB1f30+rH1ew0farw==",
+      "license": "MIT",
       "dependencies": {
         "object-assign": "^4.1.0"
       }
diff --git a/package.json b/package.json
index 39f76f1a5dd..2aebf0b9226 100644
--- a/package.json
+++ b/package.json
@@ -72,6 +72,7 @@
     "@plotly/d3-sankey": "0.7.2",
     "@plotly/d3-sankey-circular": "0.33.1",
     "@plotly/mapbox-gl": "1.13.4",
+    "@plotly/regl": "^2.1.2",
     "@turf/area": "^7.1.0",
     "@turf/bbox": "^7.1.0",
     "@turf/centroid": "^7.1.0",
@@ -105,7 +106,6 @@
     "point-in-polygon": "^1.1.0",
     "polybooljs": "^1.2.2",
     "probe-image-size": "^7.2.3",
-    "@plotly/regl": "^2.1.2",
     "regl-error2d": "^2.0.12",
     "regl-line2d": "^3.1.3",
     "regl-scatter2d": "^3.3.1",
@@ -117,10 +117,12 @@
     "to-px": "1.0.1",
     "topojson-client": "^3.1.0",
     "webgl-context": "^2.2.0",
-    "world-calendars": "^1.0.3"
+    "world-calendars": "github:archmoj/world-calendars#0faeec8544d289c94845a73fcbb813b9bb423599"
   },
   "devDependencies": {
     "@biomejs/biome": "1.8.3",
+    "@plotly/mathjax-v2": "npm:mathjax@2.7.5",
+    "@plotly/mathjax-v3": "npm:mathjax@^3.2.2",
     "amdefine": "^1.0.1",
     "assert": "^2.1.0",
     "browserify-transform-tools": "^1.7.0",
@@ -160,8 +162,6 @@
     "karma-viewport": "1.0.2",
     "lodash": "^4.17.21",
     "madge": "^8.0.0",
-    "@plotly/mathjax-v2": "npm:mathjax@2.7.5",
-    "@plotly/mathjax-v3": "npm:mathjax@^3.2.2",
     "minify-stream": "^2.1.0",
     "npm-link-check": "^5.0.1",
     "open": "^8.4.2",
diff --git a/test/jasmine/tests/lib_date_test.js b/test/jasmine/tests/lib_date_test.js
index 55d6aa7b16c..186afd033a2 100644
--- a/test/jasmine/tests/lib_date_test.js
+++ b/test/jasmine/tests/lib_date_test.js
@@ -368,6 +368,64 @@ describe('dates', function() {
                 expect(Lib.dateTime2ms(v, 'chinese')).toBeUndefined(v);
             });
         });
+
+        it('Persian calendar should convert right values', function() {
+            var leapYears = [
+                479, 483, 487, 491, 495, 499,
+                503, 508, 512, 516, 520, 524, 528, 532, 536, 541, 545, 549, 553, 557, 561, 565, 569, 574, 578, 582, 586, 590, 594, 598,
+                602, 607, 611, 615, 619, 623, 627, 631, 636, 640, 644, 648, 652, 656, 660, 664, 669, 673, 677, 681, 685, 689, 693, 697,
+                702, 706, 710, 714, 718, 722, 726, 730, 735, 739, 743, 747, 751, 755, 759, 764, 768, 772, 776, 780, 784, 788, 792, 797,
+                801, 805, 809, 813, 817, 821, 825, 830, 834, 838, 842, 846, 850, 854, 858, 863, 867, 871, 875, 879, 883, 887, 892, 896,
+                900, 904, 908, 912, 916, 920, 925, 929, 933, 937, 941, 945, 949, 953, 958, 962, 966, 970, 974, 978, 982, 986, 991, 995, 999,
+                1003, 1007, 1011, 1015, 1020, 1024, 1028, 1032, 1036, 1040, 1044, 1048, 1053, 1057, 1061, 1065, 1069, 1073, 1077, 1081, 1086, 1090, 1094, 1098,
+                1102, 1106, 1110, 1114, 1119, 1123, 1127, 1131, 1135, 1139, 1143, 1148, 1152, 1156, 1160, 1164, 1168, 1172, 1176, 1181, 1185, 1189, 1193, 1197,
+                1201, 1205, 1209, 1214, 1218, 1222, 1226, 1230, 1234, 1238, 1242, 1247, 1251, 1255, 1259, 1263, 1267, 1271, 1276, 1280, 1284, 1288, 1292, 1296,
+                1300, 1304, 1309, 1313, 1317, 1321, 1325, 1329, 1333, 1337, 1342, 1346, 1350, 1354, 1358, 1362, 1366, 1370, 1375, 1379, 1383, 1387, 1391, 1395, 1399,
+                1403, 1408, 1412, 1416, 1420, 1424, 1428, 1432, 1437, 1441, 1445, 1449, 1453, 1457, 1461, 1465, 1470, 1474, 1478, 1482, 1486, 1490, 1494, 1498,
+                1503, 1507, 1511, 1515, 1519, 1523
+            ];
+
+            var dates = [];
+
+            for(var y = 475; y < 1525; y++) {
+                if(y === 0) continue;
+                for(var m = 1; m <= 12; m++) {
+                    for(var d = 1; d <= (m < 7 ? 31 : 30); d++) {
+                        if(d === 30 && m === 12 && leapYears.indexOf(y) === -1) continue;
+
+                        dates.push([
+                            (y < 1000 ? '0' : '') + y,
+                            (m < 10 ? '0' : '') + m,
+                            (d < 10 ? '0' : '') + d
+                        ].join('-'));
+                    }
+                }
+            }
+
+            var unixIndex = dates.indexOf('1348-10-11');
+
+            var tests = [];
+            for(var i = 0; i < dates.length; i++) {
+                var date = dates[i];
+                var parts = date.split('-');
+                var d = +parts[2];
+
+                // only test days at the start/end of months
+                if(d < 3 || d > 28) {
+                    var time = (i - unixIndex) * 86400000;
+
+                    tests.push([date, time]);
+                }
+            }
+
+            tests.forEach(function(v) {
+                var calendar = 'persian';
+                var dateStr = v[0];
+                var ms = v[1];
+                expect(Lib.ms2DateTime(ms, 0, calendar)).toBe(dateStr);
+                expect(Lib.dateTime2ms(dateStr, calendar)).toBe(ms);
+            });
+        });
     });
 
     describe('cleanDate', function() {