diff --git a/src/client/ClientGameRunner.ts b/src/client/ClientGameRunner.ts
index 68794eedd..55946dce0 100644
--- a/src/client/ClientGameRunner.ts
+++ b/src/client/ClientGameRunner.ts
@@ -331,6 +331,7 @@ export class ClientGameRunner {
       Date.now(),
       update.winner,
       this.lobby.gameStartInfo.lobbyCreatedAt,
+      this.lobby.gameStartInfo.visibleAt,
     );
     endGame(record);
   }
diff --git a/src/core/Schemas.ts b/src/core/Schemas.ts
index e0dbdd5fc..8b5ed10fc 100644
--- a/src/core/Schemas.ts
+++ b/src/core/Schemas.ts
@@ -526,6 +526,7 @@ export const PlayerSchema = z.object({
 export const GameStartInfoSchema = z.object({
   gameID: ID,
   lobbyCreatedAt: z.number(),
+  visibleAt: z.number().optional(),
   config: GameConfigSchema,
   players: PlayerSchema.array(),
 });
diff --git a/src/core/Util.ts b/src/core/Util.ts
index f3dd45aad..3010b7fb6 100644
--- a/src/core/Util.ts
+++ b/src/core/Util.ts
@@ -251,6 +251,8 @@ export function createPartialGameRecord(
   winner: Winner,
   // lobby creation time (ms). Defaults to start time for singleplayer.
   lobbyCreatedAt?: number,
+  // Time the lobby became visible to players (ms).
+  visibleAt?: number,
 ): PartialGameRecord {
   const duration = Math.floor((end - start) / 1000);
   const num_turns = allTurns.length;
@@ -262,13 +264,14 @@ export function createPartialGameRecord(
   const actualLobbyCreatedAt = lobbyCreatedAt ?? start;
   const lobbyFillTime = Math.max(
     0,
-    start - Math.min(actualLobbyCreatedAt, start),
+    start - (visibleAt ?? actualLobbyCreatedAt),
   );
 
   const record: PartialGameRecord = {
     info: {
       gameID,
       lobbyCreatedAt: actualLobbyCreatedAt,
+      visibleAt,
       lobbyFillTime,
       config,
       players,
diff --git a/src/server/GameServer.ts b/src/server/GameServer.ts
index 8a41d4edb..da724214c 100644
--- a/src/server/GameServer.ts
+++ b/src/server/GameServer.ts
@@ -87,6 +87,8 @@ export class GameServer {
 
   private lobbyInfoIntervalId: ReturnType<typeof setInterval> | null = null;
 
+  private visibleAt?: number;
+
   constructor(
     public readonly id: string,
     readonly log_: Logger,
@@ -98,6 +100,9 @@ export class GameServer {
     private publicGameType?: PublicGameType,
   ) {
     this.log = log_.child({ gameID: id });
+    if (startsAt !== undefined) {
+      this.visibleAt = Date.now();
+    }
   }
 
   private get lobbyCreatorID(): ClientID | undefined {
@@ -558,6 +563,8 @@ export class GameServer {
 
   public setStartsAt(startsAt: number) {
     this.startsAt = startsAt;
+    // Record when the lobby first became visible to players, used to measure lobby fill time.
+    this.visibleAt ??= Date.now();
   }
 
   public numClients(): number {
@@ -656,6 +663,7 @@ export class GameServer {
     const result = GameStartInfoSchema.safeParse({
       gameID: this.id,
       lobbyCreatedAt: this.createdAt,
+      visibleAt: this.visibleAt,
       config: this.gameConfig,
       players: this.activeClients.map((c) => ({
         username: c.username,
@@ -1001,6 +1009,7 @@ export class GameServer {
           Date.now(),
           this.winner?.winner,
           this.createdAt,
+          this.visibleAt,
         ),
       ),
     );