---
id: mac-storage-basics.what-is-the-3-2-1-backup-rule
url: https://storagestudio.us/faq/mac-storage-basics/what-is-the-3-2-1-backup-rule
category: "Mac storage basics"
subcategory: "Time Machine basics"
question: "What is the 3-2-1 backup rule?"
alt_questions:
  - "how many backups should i have"
  - "best backup strategy mac"
  - "offsite backup rule"
  - "backup rule of thumb"
  - "three copies two media one offsite"
short_answer: "Keep 3 copies of important files, on 2 different kinds of storage, with 1 copy kept off-site — for example the Mac, a Time Machine drive and a cloud or off-site copy."
tags: ["backup", "strategy", "time machine"]
related: ["https://storagestudio.us/faq/mac-storage-basics/is-time-machine-enough-as-a-backup", "https://storagestudio.us/faq/mac-storage-basics/can-time-machine-back-up-to-icloud"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# What is the 3-2-1 backup rule?

It's a simple rule of thumb for not losing files: keep **3** copies of anything important, on **2** different kinds of storage, with **1** copy somewhere else (another building, or a cloud service).

For a Mac that might be: your files on the Mac, a Time Machine backup on an external drive, and a third copy in a cloud backup or on a drive you keep elsewhere. Moving files to an external drive to free space is not a backup on its own — the drive then holds the only copy, so back it up too.