---
id: external-drives.why-is-my-external-drive-read-only
url: https://storagestudio.us/faq/external-drives/why-is-my-external-drive-read-only
category: "External drives"
subcategory: "Drive formats"
question: "Why is my external drive read-only on my Mac?"
alt_questions:
  - "Can't write to external drive Mac"
  - "External SSD is read only"
  - "Drive is not writable Storage Studio"
  - "You can only read this disk"
  - "mac external drive read only fix"
  - "Why can't I copy files to my external drive?"
short_answer: "Usually it's NTFS (read-only on a Mac), macOS mounted it read-only after finding errors (run First Aid), a permissions setting in Get Info, or a lock switch. Storage Studio needs a writable drive."
tags: ["read-only", "ntfs", "permissions", "troubleshooting"]
related: ["https://storagestudio.us/faq/external-drives/can-i-use-an-ntfs-drive", "https://storagestudio.us/faq/external-drives/what-is-ignore-ownership-on-this-volume", "https://storagestudio.us/faq/external-drives/does-storage-studio-work-with-an-encrypted-external-drive"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# Why is my external drive read-only on my Mac?

The most common reasons:

- **It's NTFS** — macOS reads Windows NTFS drives but can't write to them. Erase it as APFS (after backing up) to use it.
- **macOS found file-system errors** and mounted it read-only to protect your data — run **First Aid** in Disk Utility.
- **Permissions** — in Finder, choose **Get Info** on the drive and check the Sharing & Permissions section.
- **A physical lock switch** on some SD cards and older drives.

Storage Studio needs to write to the drive, so a read-only drive can't be set up or used for moves; the speed test will also fail on it.