---
id: external-drives.can-i-use-a-usb-flash-drive-or-sd-card
url: https://storagestudio.us/faq/external-drives/can-i-use-a-usb-flash-drive-or-sd-card
category: "External drives"
subcategory: "Choosing a drive"
question: "Can I use a USB flash drive or an SD card as my fast drive?"
alt_questions:
  - "Will Storage Studio use an SD card for storage?"
  - "Use thumb drive as extra Mac storage"
  - "Can my MacBook's SD card slot be the fast drive?"
  - "flash drive storage studio"
  - "Is a memory card good enough to offload files to?"
short_answer: "Only if it's reformatted as APFS and passes Storage Studio's speed test. Most flash drives and SD cards arrive as FAT32 or exFAT and are often too slow to run apps from, so an external SSD is the better choice."
tags: ["flash drive", "sd card", "format", "speed test"]
related: ["https://storagestudio.us/faq/external-drives/can-i-use-a-spinning-hard-drive-as-my-fast-drive", "https://storagestudio.us/faq/external-drives/what-kind-of-external-drive-should-i-use-with-storage-studio", "https://storagestudio.us/faq/external-drives/can-i-use-a-network-drive-or-nas"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# Can I use a USB flash drive or an SD card as my fast drive?

Only if it's formatted for the Mac and passes the speed test — and even then it's usually not the best choice. Most flash drives and SD cards come formatted as FAT32 or exFAT: FAT32 can't be used at all, and exFAT is allowed only with a warning. Many are also too slow to run apps from, and Storage Studio's speed test will block or warn about those.

If you want to try one:

1. Back up anything on it, then erase it as **APFS** in Disk Utility.
2. Open **Choose Drive**, select it and click **Run benchmark**.
3. Use it only if the verdict is good.

For apps and folders you open every day, a proper external SSD is the safer, faster option.