How to Encrypt a Flash Drive or External Hard Drive Using BitLocker (Windows 10 & 11)

Important: Always back up your BitLocker recovery key. Without it, your files may be permanently inaccessible.

Encrypting a flash drive or external hard drive adds an extra layer of security to protect your data if the device is lost or stolen. Windows 10 and Windows 11 include BitLocker To Go, which allows you to encrypt removable storage easily.

Follow the instructions below based on your device and version of Windows.

Before You Begin

• You must be using Windows 10 Pro, Enterprise, or Education OR Windows 11 Pro, Enterprise, or Education.
  (BitLocker is not available in Home editions.)

• Make sure the flash drive or external drive is connected.

• Ensure important data on the drive is backed up before encrypting (optional but recommended).

How to Encrypt Your Flash Drive or External Drive

1. Open This PC

• Press Windows + E to open File Explorer.

• Click This PC on the left.

2. Right-Click the Flash Drive

• Find your flash drive or external hard drive under Devices and drives.

• Right-click it and select Turn on BitLocker.

3. Choose How You Want to Unlock the Drive

You can choose from:

• Password unlock (recommended)

• Smart card unlock (business environments)

Select Use a password to unlock the drive and enter a strong password.

4. IMPORTANT: Back Up Your BitLocker Recovery Key

This key allows you to unlock your drive if you forget your password or if Windows cannot access your encrypted device.

You will be prompted with options to save the recovery key:

Recommended Backup Options

✔ Save to your Microsoft account (if available)
✔ Save to a file (store in a secure location—NOT on the same drive)
✔ Print the recovery key
✔ Save in your IT-approved password manager or secure vault

Do NOT

❌ Store the recovery key on the encrypted drive
❌ Email the recovery key without encryption

If you lose your BitLocker recovery key, your data cannot be recovered. Back it up in at least two places.

Click Next when finished.

5. Choose How Much of the Drive to Encrypt

You will be asked to choose one of the following:

Encrypt used disk space only (faster)

Best for new drives.

Encrypt entire drive (slower, but recommended)

Best for drives already containing data.

Select your preferred option and click Next.

6. Choose the Encryption Mode

• New encryption mode — Best for internal drives

• Compatible mode — Best for flash drives and external hard drives, especially if you plan to use the drive on older Windows systems

Select Compatible mode for removable storage.
Click Next.

7. Start Encryption

Click Start encrypting.

The process may take a few minutes to several hours, depending on:

• Drive size

• Drive speed

• Amount of data

Once complete, the drive will display a lock icon in File Explorer.

How to Use Your Encrypted Drive

Unlocking

When you plug in the encrypted drive:

• Windows will prompt you for the BitLocker password.

• Enter your password to access the drive normally.

Locking

To manually lock the drive:

• Right-click the drive → Manage BitLocker → Lock drive.

How to Turn Off BitLocker (Decrypt the Drive)

If you no longer need encryption:

1. Right-click the encrypted drive

2. Select Manage BitLocker

3. Click Turn off BitLocker

4. Confirm and allow the drive to decrypt

Summary

✔ BitLocker protects your flash drive or external drive with strong encryption
✔ Always back up your BitLocker recovery key in at least two places
✔ Use “Compatible mode” for external drives
✔ Encryption helps protect sensitive data from loss, theft, or unauthorized access