System requirements
BitLocker has the following hardware requirements:

For BitLocker to use the system integrity check provided by a Trusted Platform Module (TPM), the computer must have TPM 1.2 or later.
If your computer does not have a TPM, enabling BitLocker requires that you save a startup key on a removable device, such as a USB flash drive.
A computer with a TPM must also have a Trusted Computing Group (TCG)-compliant BIOS or UEFI firmware. The BIOS or UEFI firmware establishes a chain of trust for the pre-operating system startup, and it must include support for TCG-specified Static Root of Trust Measurement.


A computer without a TPM does not require TCG-compliant firmware.
The system BIOS or UEFI firmware (for TPM and non-TPM computers) must support the USB mass storage device class, including reading small files on a USB flash drive in the pre-operating system environment.
The hard disk must be partitioned with at least two drives: The operating system drive (or boot drive) contains the operating system and its support files. It must be formatted with the NTFS file system.
The system drive contains the files that are needed to load Windows after the firmware has prepared the system hardware. BitLocker is not enabled on this drive.


For BitLocker to work, the system drive must not be encrypted, must differ from the operating system drive, and must be formatted with the FAT32 file system on computers that use UEFI-based firmware or with the NTFS file system on computers that use BIOS firmware.
We recommend that system drive be approximately 350 MB in size.
 After BitLocker is turned on it should have approximately 250 MB of free space.
When installed on a new computer, Windows will automatically create the partitions that are required for BitLocker.
When installing the BitLocker optional component on a server you will also need to install the Enhanced Storage feature, which is used to support hardware encrypted drives.