diff --git a/packages/frontend/web-ui/src/game/helpers/getGameSlotIndex.spec.ts b/packages/frontend/web-ui/src/game/helpers/getGameSlotIndex.spec.ts
new file mode 100644
index 000000000..1b9a78001
--- /dev/null
+++ b/packages/frontend/web-ui/src/game/helpers/getGameSlotIndex.spec.ts
@@ -0,0 +1,81 @@
+import { beforeAll, describe, expect, it } from '@jest/globals';
+
+import { models as apiModels } from '@cornie-js/api-models';
+
+import { getGameSlotIndex } from './getGameSlotIndex';
+
+describe(getGameSlotIndex.name, () => {
+  describe('having a user and a game without a slot belonging to that user', () => {
+    let gameFixture: apiModels.GameV1;
+
+    let userFixture: apiModels.UserV1;
+
+    beforeAll(() => {
+      gameFixture = {
+        id: 'id-fixture',
+        isPublic: true,
+        state: {
+          slots: [],
+          status: 'nonStarted',
+        },
+      };
+
+      userFixture = {
+        active: true,
+        id: 'id-fixture',
+        name: 'name-fixture',
+      };
+    });
+
+    describe('when called', () => {
+      let result: unknown;
+
+      beforeAll(() => {
+        result = getGameSlotIndex(gameFixture, userFixture);
+      });
+
+      it('should return expected result', () => {
+        expect(result).toBeNull();
+      });
+    });
+  });
+
+  describe('having a user and a game with a slot belonging to that user', () => {
+    let gameFixture: apiModels.GameV1;
+
+    let userFixture: apiModels.UserV1;
+
+    beforeAll(() => {
+      userFixture = {
+        active: true,
+        id: 'id-fixture',
+        name: 'name-fixture',
+      };
+
+      gameFixture = {
+        id: 'id-fixture',
+        isPublic: true,
+        state: {
+          slots: [
+            {
+              userId: userFixture.id,
+            },
+          ],
+          status: 'nonStarted',
+        },
+      };
+    });
+
+    describe('when called', () => {
+      let result: unknown;
+
+      beforeAll(() => {
+        result = getGameSlotIndex(gameFixture, userFixture);
+      });
+
+      it('should return expected result', () => {
+        expect(result).toBe('0');
+      });
+    });
+  });
+});
diff --git a/packages/frontend/web-ui/src/game/helpers/getGameSlotIndex.ts b/packages/frontend/web-ui/src/game/helpers/getGameSlotIndex.ts
new file mode 100644
index 000000000..ca712e888
--- /dev/null
+++ b/packages/frontend/web-ui/src/game/helpers/getGameSlotIndex.ts
@@ -0,0 +1,23 @@
+import { models as apiModels } from '@cornie-js/api-models';
+
+export function getGameSlotIndex(
+  game: apiModels.GameV1 | undefined,
+  user: apiModels.UserV1,
+): string | null {
+  if (game === undefined) {
+    return null;
+  }
+
+  for (let i: number = 0; i < game.state.slots.length; ++i) {
+    const gameSlot: apiModels.ActiveGameSlotV1 | apiModels.FinishedGameSlotV1 =
+      game.state.slots[i] as
+        | apiModels.ActiveGameSlotV1
+        | apiModels.FinishedGameSlotV1;
+
+    if (gameSlot.userId === user.id) {
+      return i.toString();
+    }
+  }
+
+  return null;
+}