How to clone a hard drive to an SSD (and fix a clone that won't boot)
Swapping an old spinning hard drive for an SSD is the biggest speed-up most older computers can get. Cloning copies everything across, so the computer starts up exactly as before, just much faster.
Before you start
- Will it fit? What matters is the space used, not the size of the old drive. A 1 TB hard drive with 180 GB used clones fine to a 256 GB SSD, though 500 GB gives room to grow. Aim to leave at least 10-20% of the SSD free. If it won't fit, move photos and videos to another drive first.
- Is the old drive healthy? Cloning reads every used part of the disk. If the drive clicks, freezes or its health check shows reallocated or pending sectors, copy your files off first, then clone (or reinstall). See checking drive health and the SMART report explainer.
- Back up. A clone is a one-way copy to the new drive, but picking the wrong disk as the target wipes it. A separate backup makes that mistake harmless.
- BitLocker or device encryption? Suspend it before cloning (Control Panel > BitLocker > Suspend protection, or
manage-bde -protectors -disable C:as admin) and make sure you have your recovery key. Turn it back on afterwards. - Tidy up. Empty the recycle bin and run Disk Cleanup; less data means a faster clone.
Connecting the SSD
| Computer | New SSD | How to connect it for cloning |
|---|---|---|
| Desktop | 2.5-inch SATA or M.2 | Fit it inside in a spare SATA port or M.2 slot alongside the old drive |
| Laptop with one 2.5-inch bay | 2.5-inch SATA SSD | A USB-to-SATA adapter cable, then swap the drives after cloning |
| Laptop with an M.2 slot | M.2 NVMe (or SATA M.2: check which the slot takes) | A USB M.2 enclosure that matches the SSD type, or a second M.2 slot if there is one |
A new SSD often doesn't appear until it's initialised. Many cloning tools do that for you; if not, see new SSD not showing up.
Cloning on Windows
- Pick a tool. Most SSD brands offer a free cloning tool for their own drives (for example Samsung Data Migration, or the free Acronis editions some drive brands provide). Clonezilla is free, works with any drive from a USB boot stick, and is happiest when the new drive is the same size or bigger. Paid tools handle "clone to a smaller drive" more smoothly.
- Choose the whole disk as the source, with all its partitions: the small EFI System partition (the part that actually starts Windows), the Microsoft Reserved one, the Windows (C:) partition and the Recovery partition. Leaving out the EFI partition is the most common reason a clone won't boot.
- Choose the SSD as the target and read the disk size twice before you start. Everything on the target is overwritten.
- Let it fill the drive. If the tool offers to resize partitions to fit the new disk, say yes so C: uses the extra space.
- Swap or set the boot order. Power off, fit the SSD where the old drive was (laptops), or in the UEFI/BIOS settings put the SSD first. Start up with only the SSD connected the first time, so you know it's the one that booted.
After the clone
- Space missing? Open Disk Management (
diskmgmt.msc). If there's unallocated space after C:, right-click C: > Extend Volume. If a Recovery partition sits between C: and the free space, Extend is greyed out; a partition tool can move it, or redo the clone with "resize to fit". - Check TRIM is on, so the SSD stays fast:
fsutil behavior query DisableDeleteNotifyshould say= 0. Windows' "Optimize Drives" is safe on SSDs: it sends TRIM rather than defragmenting. - Keep the old drive for a week as a fallback, then wipe it properly before reusing or giving it away: see how to wipe a drive.
When the clone won't boot or the clone fails
| What happens | Likely cause | Fix |
|---|---|---|
| Computer still starts from the old drive | Boot order | Put the SSD first in UEFI/BIOS boot settings, or disconnect the old drive |
| "No bootable device" or straight into BIOS | EFI System partition not cloned, or a UEFI vs Legacy (CSM) mismatch | Re-clone the whole disk; match the boot mode to the old drive (GPT disks boot UEFI, MBR disks boot Legacy) |
| Blue screen INACCESSIBLE_BOOT_DEVICE | The storage controller mode changed, for example a RAID/Intel RST vs AHCI setting | Put the SATA mode back to what it was; if it must change, set Windows to start in Safe Mode once first |
| Asks for a BitLocker recovery key | Encryption noticed new hardware | Enter the recovery key (from your Microsoft account or printout), then suspend and resume protection |
| Clone stops at the same percentage | Unreadable sectors on the old drive | Run chkdsk C: /scan; if the drive is failing, rescue files first or image it with ddrescue (see failing drives) |
| "Target disk is too small" | The tool copies partitions at full size | Shrink C: first in Disk Management, free up space, or use a tool that resizes during the clone |
Mac and Linux
- Mac: Macs from recent years already have SSDs, often soldered in. For an older Intel Mac with a hard drive, the most reliable route is to fit the SSD, install macOS on it from Recovery, then use Migration Assistant to bring apps, files and settings across from the old drive or a Time Machine backup.
- Linux: booted from a live USB,
sudo dd if=/dev/sdOLD of=/dev/sdNEW bs=4M status=progress conv=fsynccopies a disk to one of the same size or bigger. Check the device names withlsblkfirst: swapping them destroys the old drive. Grow the last partition afterwards with GParted. For a drive with read errors, useddrescueinstead.
Clone or fresh install?
Cloning keeps everything as it was, including any mess. A fresh install is cleaner and fixes old software problems, but means reinstalling apps and signing in again. If the old system was slow because of clutter rather than the hard drive, a fresh install on the SSD gives the bigger improvement.
Related
New SSD slower than expected? · Games stutter loading new areas? · New SSD not showing up · Check hard drive health · Drive clicking or beeping · Wipe the old drive before giving it away · USB stick or SD card write-protected
Questions
Can I clone a bigger hard drive to a smaller SSD?
Yes, if the space actually used fits on the SSD with room to spare. Some free tools copy partitions at their full size and refuse, so shrink the Windows partition first in Disk Management or use a tool that resizes during the clone.
Do I need to reinstall Windows after cloning?
No. A complete clone, including the small EFI boot partition, starts up exactly like the old drive did, and Windows activation stays because it's tied to the computer, not the drive.
Why won't my cloned SSD boot?
Usually the computer is still set to boot from the old drive, the EFI System partition wasn't copied, or the boot mode or SATA controller mode doesn't match. Start with only the SSD connected and check the boot order first.
Why does my new SSD show less space than it should?
The clone kept the old partition size and left the rest unallocated. Extend the C: partition in Disk Management; if a Recovery partition is in the way, move it with a partition tool or redo the clone with resize-to-fit.
How long does cloning take?
Mostly it depends on how much data is used and how fast the old drive reads. Old laptop hard drives read roughly 80-120 MB/s, so 200 GB takes around 30-45 minutes; a USB 2 adapter is much slower.
Published · updated .