Before you format, you must select a file system that determines how your data is organized and which devices can read it.
| File System | Best For | Compatibility | File Size Limit | | :--- | :--- | :--- | :--- | | | Windows computers only. | Windows (Read/Write), Mac (Read Only). | None practical. | | APFS | Modern Mac computers (SSD/Flash). | Mac only. Not readable by Windows. | None practical. | | Mac OS Extended | Older Mac computers (HDD). | Mac only. | None practical. | | exFAT | Cross-platform use. Ideal for drives used on both Windows and Mac. | Windows & Mac (Read/Write). | None practical. | | FAT32 | Small drives, older devices. | Universal. | 4GB max per file. | how to format an external hard drive