Formatting disks and drives: frequently asked questions

Hard disks, the primary storage devices on your computer, need to be formatted before you can use them. When you format a disk, you configure it with a file system so that Windows can store information on the disk. Hard disks in new computers running Windows are already formatted. If you buy an additional hard disk to expand the storage of your computer, you might need to format it.

Storage devices such as USB flash drives and flash memory cards usually come preformatted by the manufacturer, so you probably won't need to format them. CDs and DVDs, on the other hand, use different formats from hard disks and removable storage devices. For information about formatting CDs and DVDs, see Which CD or DVD format should I use?

Warning

  • Formatting erases any existing files on a hard disk. If you format a hard disk that has files on it, the files will be deleted.

Here are answers to some common questions about formatting disks and drives.

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When do I need to format a disk or drive?

Usually, only when adding additional storage to your computer. If you install a new hard disk on your computer, it must be formatted with a file system, such as NTFS, before Windows can store files on it.

What do I need to do to format a hard disk?

Before formatting a hard disk, you must first create one or more partitions on it. After you've partitioned the hard disk, you can format each partition. (The terms volume and partition are often used interchangeably.) You can partition the hard disk so it contains a single volume or several volumes. Each volume is assigned its own drive letter. For more information, see Create and format a hard disk partition.

What file system should I use?

For this version of Windows, the best choice for hard disks is NTFS. Some previous versions of Windows required FAT32, so there are a few circumstances, such as a multiboot computer, where FAT32 might be required. For more information, see Convert a hard disk or partition to FAT32 format.

What's a quick format?

Quick format is a formatting option that creates a new file table on a hard disk but does not fully overwrite or erase the disk. A quick format is much faster than a normal format, which fully erases any existing data on the hard disk.

What are partitions and volumes?

A partition is an area of a hard disk that can be formatted and assigned a drive letter. On a basic disk (the most common type of disk) a volume is a formatted primary partition or logical drive. (The terms volume and partition are often used interchangeably.) Your system partition is typically labeled with the letter C. Letters A and B are reserved for removable drives or floppy disk drives. Some computers have hard disks that are partitioned as a single partition, so your whole hard disk is represented by the letter C. Other computers might have an additional partition that contains recovery tools, in case the information on your C partition becomes damaged or unusable.

How do I create more partitions?

You can create more partitions or volumes only if the hard disk contains unallocated space (unformatted space that is not part of an existing partition or volume). To create unallocated space, you can shrink a volume, or use a third-party partitioning tool. For more information, see Can I repartition my hard disk?

How do I add a new hard disk?

If you're adding an internal hard disk, refer to the information that came with the new hard disk. If you're installing an external hard disk that is connected by a USB cable, this version of Windows should recognize the hard disk. If this version of Windows does not recognize the disk, see Create and format a hard disk partition.

What does reformatting my hard disk do?

Reformatting refers to formatting a hard disk or partition that already has been formatted or that contains data. Reformatting a disk deletes all data on the disk.

In some older versions of Windows, reformatting a hard disk and then reinstalling Windows was sometimes recommended as a method for fixing a serious computer problem. Reformatting would fix the problem at the expense of deleting everything on the computer. You would then have to reinstall your programs by using the original installation files or discs, and then restore all of your personal files, such as documents, music, and pictures, from backups that you had made beforehand.

This version of Windows offers a number of recovery options that are less drastic and provide a better place to start fixing your computer problems. For more information, search Windows Help and Support for "recovery options." Reformatting and reinstalling should be considered as a last resort that's only performed after all other recovery or diagnostic options have failed.

Why do I get an error when I try to reformat my hard disk?

You can't reformat a disk or partition that is currently in use, including the partition that contains Windows. This is a safety feature so that you can't delete Windows by accident. To reformat your computer's hard disk and reinstall Windows, restart your computer using the Windows installation disc (this is commonly known as booting from the installation disc). During the Setup process, you can repartition and reformat your hard disk and then reinstall Windows. The process will erase your files and programs, so be sure to back up your data and program files before you begin. For more information, search Windows Help and Support for "installing and reinstalling Windows."