---
id: external-drives.what-is-the-efi-partition
url: https://storagestudio.us/faq/external-drives/what-is-the-efi-partition
category: "External drives"
subcategory: "Drive formats"
question: "What is the hidden EFI partition on my external drive?"
alt_questions:
  - "EFI partition external drive Mac"
  - "Can I delete the EFI partition?"
  - "Small hidden partition on my disk"
  - "efi volume mounted on desktop"
short_answer: "It's a small, normally hidden system partition that GUID-formatted drives carry for starting up a computer. It uses very little space — leave it alone and don't delete or reformat it separately."
tags: ["efi", "partition", "guid"]
related: ["https://storagestudio.us/faq/external-drives/why-does-one-drive-show-two-icons", "https://storagestudio.us/faq/external-drives/disk-utility-only-shows-volumes", "https://storagestudio.us/faq/external-drives/how-do-i-reformat-an-external-drive-to-apfs"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# What is the hidden EFI partition on my external drive?

It's a small system partition that drives formatted with the **GUID Partition Map** scheme carry. It's used when starting up a computer and is normally hidden. It takes very little space; leave it alone, and don't delete or reformat it on its own.

If it appears in Finder or Disk Utility, it's usually because something mounted it on purpose; ejecting it is harmless. See [why one drive can show as two](https://storagestudio.us/faq/external-drives/why-does-one-drive-show-two-icons).