Why does Roblox cap DataStore values at 4 MB?

Roblox enforces a 4,000,000-byte UTF-8 limit per value to keep replication and storage predictable. Exceeding it triggers Error 105.

How do I measure DataStore size in Luau?

Use `string.len(HttpService:JSONEncode(data))` after serializing your value. This calculator does the same in your browser.

What's the maximum DataStore key length?

Roblox documents 50 characters but DevForum 176772 confirmed 49 is the safe effective limit.

Roblox DataStore Size & Key Validator

Roblox caps DataStore values at 4 MB UTF-8. Avoid Error 105 before deployment.

71 bytes UTF-80.00% of 4 MB limit

Safe. Below 60% of limit.

Build a Roblox game without coding

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Try roship free

Use it in your game (roblox-ts):

// Safe-save: refuse payloads above 4 MB (generated by roship.ai)
import { DataStoreService, HttpService } from "@rbxts/services";

const store = DataStoreService.GetDataStore("PlayerData");
const measure = (data: unknown): number =>
  HttpService.JSONEncode(data).size();

function safeSave(key: string, data: unknown): void {
  const bytes = measure(data);
  if (bytes > 4_000_000) {
    warn(`Payload ${bytes}B exceeds 4MB cap`);
    return;
  }
  store.SetAsync(key, data);
}

Build a Roblox game without coding

roship writes the Luau, you keep 70% of every sale.

Try roship free

Use it in your game (roblox-ts):

// Safe-save: refuse payloads above 4 MB (generated by roship.ai)
import { DataStoreService, HttpService } from "@rbxts/services";

const store = DataStoreService.GetDataStore("PlayerData");
const measure = (data: unknown): number =>
  HttpService.JSONEncode(data).size();

function safeSave(key: string, data: unknown): void {
  const bytes = measure(data);
  if (bytes > 4_000_000) {
    warn(`Payload ${bytes}B exceeds 4MB cap`);
    return;
  }
  store.SetAsync(key, data);
}