diff --git a/Justfile b/Justfile
index e603d13..09f7a82 100644
--- a/Justfile
+++ b/Justfile
@@ -1,10 +1,12 @@
 set quiet
 
-default: venv
-	venv/bin/python3 scripts/update-readme.py
+default: venv readme
 	venv/bin/python3 scripts/update-calendar.py
 	venv/bin/python3 scripts/update-badges.py
 
+readme:
+	venv/bin/python3 scripts/update-readme.py
+
 venv:
 	#!/bin/bash
 
diff --git a/README.md b/README.md
index 35261aa..5d653c6 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,11 @@ This repo contains a [releases-v1.json](./releases-v1.json) file that tracks all
 |   stable2412-2 | ~2025-02-17 | ~2025-02-20 |  | Planned |
 |   stable2412-3 | ~2025-03-17 | ~2025-03-20 |  | Planned |
 |   (9 more) |  |  | | |
+| **stable2503** | ~2025-02-17 | ~2025-03-31 | ~2026-03-31 | Planned |
+|   stable2503-1 | ~2025-04-28 | ~2025-05-01 |  | Planned |
+|   stable2503-2 | ~2025-05-26 | ~2025-05-29 |  | Planned |
+|   stable2503-3 | ~2025-06-23 | ~2025-06-26 |  | Planned |
+|   (10 more) |  |  | | |
 
 <!-- TEMPLATE END -->
 
diff --git a/releases-v1.ics b/releases-v1.ics
index 5c4a954..222bd0c 100644
--- a/releases-v1.ics
+++ b/releases-v1.ics
@@ -554,4 +554,207 @@ DTEND;VALUE=DATE:20251219
 DESCRIPTION:Release of stable2412-12 (planned)\n\nFull Calendar: https://g
  ithub.com/paritytech/release-registry?tab=readme-ov-file#calendar
 END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503 Cutoff
+DTSTART;VALUE=DATE:20250217
+DTEND;VALUE=DATE:20250218
+DESCRIPTION:Cutoff for stable2503 (planned)\n\nFull Calendar: https://gith
+ ub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503 Release
+DTSTART;VALUE=DATE:20250331
+DTEND;VALUE=DATE:20250401
+DESCRIPTION:Release of stable2503 (planned)\n\nFull Calendar: https://gith
+ ub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503 End of Life
+DTSTART;VALUE=DATE:20260331
+DTEND;VALUE=DATE:20260401
+DESCRIPTION:End of Life for stable2503\n\nFull Calendar: https://github.co
+ m/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-1 Cutoff
+DTSTART;VALUE=DATE:20250428
+DTEND;VALUE=DATE:20250429
+DESCRIPTION:Cutoff for stable2503-1 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-1 Release
+DTSTART;VALUE=DATE:20250501
+DTEND;VALUE=DATE:20250502
+DESCRIPTION:Release of stable2503-1 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-2 Cutoff
+DTSTART;VALUE=DATE:20250526
+DTEND;VALUE=DATE:20250527
+DESCRIPTION:Cutoff for stable2503-2 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-2 Release
+DTSTART;VALUE=DATE:20250529
+DTEND;VALUE=DATE:20250530
+DESCRIPTION:Release of stable2503-2 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-3 Cutoff
+DTSTART;VALUE=DATE:20250623
+DTEND;VALUE=DATE:20250624
+DESCRIPTION:Cutoff for stable2503-3 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-3 Release
+DTSTART;VALUE=DATE:20250626
+DTEND;VALUE=DATE:20250627
+DESCRIPTION:Release of stable2503-3 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-4 Cutoff
+DTSTART;VALUE=DATE:20250728
+DTEND;VALUE=DATE:20250729
+DESCRIPTION:Cutoff for stable2503-4 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-4 Release
+DTSTART;VALUE=DATE:20250731
+DTEND;VALUE=DATE:20250801
+DESCRIPTION:Release of stable2503-4 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-5 Cutoff
+DTSTART;VALUE=DATE:20250825
+DTEND;VALUE=DATE:20250826
+DESCRIPTION:Cutoff for stable2503-5 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-5 Release
+DTSTART;VALUE=DATE:20250828
+DTEND;VALUE=DATE:20250829
+DESCRIPTION:Release of stable2503-5 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-6 Cutoff
+DTSTART;VALUE=DATE:20250922
+DTEND;VALUE=DATE:20250923
+DESCRIPTION:Cutoff for stable2503-6 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-6 Release
+DTSTART;VALUE=DATE:20250925
+DTEND;VALUE=DATE:20250926
+DESCRIPTION:Release of stable2503-6 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-7 Cutoff
+DTSTART;VALUE=DATE:20251027
+DTEND;VALUE=DATE:20251028
+DESCRIPTION:Cutoff for stable2503-7 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-7 Release
+DTSTART;VALUE=DATE:20251030
+DTEND;VALUE=DATE:20251031
+DESCRIPTION:Release of stable2503-7 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-8 Cutoff
+DTSTART;VALUE=DATE:20251124
+DTEND;VALUE=DATE:20251125
+DESCRIPTION:Cutoff for stable2503-8 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-8 Release
+DTSTART;VALUE=DATE:20251127
+DTEND;VALUE=DATE:20251128
+DESCRIPTION:Release of stable2503-8 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-9 Cutoff
+DTSTART;VALUE=DATE:20251222
+DTEND;VALUE=DATE:20251223
+DESCRIPTION:Cutoff for stable2503-9 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-9 Release
+DTSTART;VALUE=DATE:20251225
+DTEND;VALUE=DATE:20251226
+DESCRIPTION:Release of stable2503-9 (planned)\n\nFull Calendar: https://gi
+ thub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-10 Cutoff
+DTSTART;VALUE=DATE:20260126
+DTEND;VALUE=DATE:20260127
+DESCRIPTION:Cutoff for stable2503-10 (planned)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-10 Release
+DTSTART;VALUE=DATE:20260129
+DTEND;VALUE=DATE:20260130
+DESCRIPTION:Release of stable2503-10 (planned)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-11 Cutoff
+DTSTART;VALUE=DATE:20260223
+DTEND;VALUE=DATE:20260224
+DESCRIPTION:Cutoff for stable2503-11 (planned)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-11 Release
+DTSTART;VALUE=DATE:20260226
+DTEND;VALUE=DATE:20260227
+DESCRIPTION:Release of stable2503-11 (planned)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-12 Cutoff
+DTSTART;VALUE=DATE:20260323
+DTEND;VALUE=DATE:20260324
+DESCRIPTION:Cutoff for stable2503-12 (planned)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-12 Release
+DTSTART;VALUE=DATE:20260326
+DTEND;VALUE=DATE:20260327
+DESCRIPTION:Release of stable2503-12 (planned)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-13 Cutoff
+DTSTART;VALUE=DATE:20260427
+DTEND;VALUE=DATE:20260428
+DESCRIPTION:Cutoff for stable2503-13 (planned)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
+BEGIN:VEVENT
+SUMMARY:stable2503-13 Release
+DTSTART;VALUE=DATE:20260430
+DTEND;VALUE=DATE:20260501
+DESCRIPTION:Release of stable2503-13 (planned)\n\nFull Calendar: https://g
+ ithub.com/paritytech/release-registry?tab=readme-ov-file#calendar
+END:VEVENT
 END:VCALENDAR
diff --git a/releases-v1.json b/releases-v1.json
index b18b7bd..127046e 100644
--- a/releases-v1.json
+++ b/releases-v1.json
@@ -398,8 +398,153 @@
             "state": "planned"
           }
         ]
+      },
+      {
+        "name": "stable2503",
+        "cutoff": {
+          "estimated": "2025-02-17"
+        },
+        "publish": {
+          "estimated": "2025-03-31"
+        },
+        "state": "planned",
+        "endOfLife": {
+          "estimated": "2026-03-31"
+        },
+        "patches": [
+          {
+            "name": "stable2503-1",
+            "cutoff": {
+              "estimated": "2025-04-28"
+            },
+            "publish": {
+              "estimated": "2025-05-01"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-2",
+            "cutoff": {
+              "estimated": "2025-05-26"
+            },
+            "publish": {
+              "estimated": "2025-05-29"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-3",
+            "cutoff": {
+              "estimated": "2025-06-23"
+            },
+            "publish": {
+              "estimated": "2025-06-26"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-4",
+            "cutoff": {
+              "estimated": "2025-07-28"
+            },
+            "publish": {
+              "estimated": "2025-07-31"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-5",
+            "cutoff": {
+              "estimated": "2025-08-25"
+            },
+            "publish": {
+              "estimated": "2025-08-28"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-6",
+            "cutoff": {
+              "estimated": "2025-09-22"
+            },
+            "publish": {
+              "estimated": "2025-09-25"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-7",
+            "cutoff": {
+              "estimated": "2025-10-27"
+            },
+            "publish": {
+              "estimated": "2025-10-30"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-8",
+            "cutoff": {
+              "estimated": "2025-11-24"
+            },
+            "publish": {
+              "estimated": "2025-11-27"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-9",
+            "cutoff": {
+              "estimated": "2025-12-22"
+            },
+            "publish": {
+              "estimated": "2025-12-25"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-10",
+            "cutoff": {
+              "estimated": "2026-01-26"
+            },
+            "publish": {
+              "estimated": "2026-01-29"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-11",
+            "cutoff": {
+              "estimated": "2026-02-23"
+            },
+            "publish": {
+              "estimated": "2026-02-26"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-12",
+            "cutoff": {
+              "estimated": "2026-03-23"
+            },
+            "publish": {
+              "estimated": "2026-03-26"
+            },
+            "state": "planned"
+          },
+          {
+            "name": "stable2503-13",
+            "cutoff": {
+              "estimated": "2026-04-27"
+            },
+            "publish": {
+              "estimated": "2026-04-30"
+            },
+            "state": "planned"
+          }
+        ]
       }
     ],
     "changelog": "https://github.com/paritytech/polkadot-sdk/releases/tag/$TAG"
   }
-}
+}
\ No newline at end of file