You'll need physical access to your computer and either the manufacturer's master password or a way to reset the CMOS battery

A BIOS password locks you out of your computer's firmware settings before Windows even loads. If you've forgotten yours, you cannot straightforward restart and try again — the password prompt appears first. Removing it requires either knowing the manufacturer's master password for your specific computer model, resetting the CMOS battery that stores the password, or contacting the manufacturer with proof of ownership.

The method that works depends on your computer type (desktop, laptop, or brand-specific model) and whether you still have access to the machine. If this is your own computer and you've straightforward forgotten the password, the CMOS reset is usually fastest. If someone else set the password and locked you out, you'll need the master password or manufacturer support.

Key Takeaways

  • BIOS passwords are stored on a small battery-backed chip called the CMOS, which you can reset by removing the battery for a few minutes on most desktops.
  • Laptops often require disassembly to reach the CMOS battery, and some newer models have no removable battery at all.
  • Many manufacturers have master passwords that work across all their machines — Dell, HP, Lenovo, and others publish these for legitimate owners.
  • If you cannot reset the CMOS and do not know the master password, contact the manufacturer with your proof of purchase or service tag number.
  • Removing a BIOS password you set yourself is straightforward; removing one set by someone else may require ownership verification.

Resetting the CMOS battery on a desktop computer

The CMOS battery is a small coin-shaped battery on your motherboard that stores BIOS settings, including the password. Removing it for a few minutes clears the password and resets all BIOS settings to factory defaults. This is the fastest method if you have a desktop.

Power off your computer completely and unplug it from the wall. Open the case by removing the side panel — usually held by two thumbscrews or clips. Locate the CMOS battery on the motherboard; it looks like a large watch battery, typically silver and round, usually near the edge of the board. Note its position, then gently pry it out using a plastic tool or the edge of a credit card. Leave it out for five to ten minutes, then reinsert it. Close the case, plug in the power, and restart. The BIOS password should be gone, and you can set a new one if you want.

If you cannot find the battery or it does not seem to be removable, check your motherboard manual or search for your specific motherboard model online. Some boards have the battery soldered in place, which requires a different approach.

Removing the CMOS battery from a laptop

Laptop CMOS batteries are harder to reach because the entire bottom panel or keyboard often needs to come off. The process varies widely by brand and model, so your first step should be to search for your exact laptop model plus "CMOS battery removal" or "reset BIOS password."

Most laptops require you to remove the bottom panel, which is usually held by several small screws. Take a photo of the screw locations before you remove them so you can put them back in the right places. Once the panel is off, locate the CMOS battery — it will look the same as on a desktop. Remove it for five to ten minutes, then reinstall it. Reassemble the laptop and restart.

Some newer laptops, particularly thin models from Apple, Dell XPS, or Lenovo ThinkPad X-series, have no removable CMOS battery. If you cannot find one after opening the panel, your laptop likely uses a non-removable battery and you will need to use the master password or contact the manufacturer.

Using manufacturer master passwords

Dell, HP, Lenovo, Acer, ASUS, and other major manufacturers have master passwords that unlock BIOS on their machines. These are not secret — they are published for legitimate owners who have forgotten their passwords. The master password varies by manufacturer and sometimes by model line.

Search for "[Your Brand] BIOS master password" — for example, "Dell BIOS master password" or "HP BIOS master password." You will find lists of common master passwords for each brand. Try them one at a time at the BIOS password prompt. If one works, you are in. You can then remove the password entirely or set a new one that you will remember.

If none of the published master passwords work, it may mean the computer is very old, uses a regional variant, or was set by the manufacturer with a custom password. In that case, contact the manufacturer's support line with your service tag or serial number and proof of purchase.

Contacting the manufacturer for password removal

If you own the computer and can prove it, the manufacturer will help you remove the BIOS password. You will need your service tag (a number on the bottom of the machine or inside the case), serial number, or proof of purchase such as a receipt or order confirmation.

Call the manufacturer's support line — Dell, HP, Lenovo, and others all have dedicated support for this issue. Explain that you have forgotten your BIOS password and provide your proof of ownership. They may ask you to answer security questions or provide additional information. Once verified, they will either give you a master password for your specific machine or walk you through a reset procedure.

This process usually takes one phone call but may take a few business days if they need to verify your purchase through their records. Keep your service tag and proof of purchase handy before you call.

What happens after you remove the BIOS password

When you reset the CMOS battery, all BIOS settings return to factory defaults. This means any custom settings you had — boot order, fan speeds, overclocking settings, or security features — will be wiped. Write down any custom settings before you reset if you can access the BIOS without the password prompt.

After the reset, your computer will boot normally and you can set a new BIOS password if you want one. If you do set a new password, write it down somewhere safe, such as a password manager or a locked drawer. A BIOS password is useful for security, but only if you remember it.

Preventing lockout in the future

If you set a BIOS password for security, store it in a password manager like Bitwarden, 1Password, or KeePass rather than relying on memory. Password managers are encrypted and backed up, so you can retrieve the password even if you forget it.

If someone else has access to your computer and you want to prevent them from changing BIOS settings, a BIOS password is useful. However, it is not a substitute for a strong Windows login password or full-disk encryption. Someone with physical access to your computer can still reset the CMOS battery, so BIOS passwords are best used as one layer of security alongside other protections.

Frequently Asked Questions

Will resetting the CMOS battery erase my files or Windows?

No. The CMOS battery only stores BIOS settings, not your files or operating system. Your Windows installation, documents, photos, and programs will remain untouched. Only BIOS settings like boot order and security features will reset to factory defaults.

Can I remove a BIOS password without opening my computer?

Not without the master password or manufacturer support. If you do not know the password and cannot access the BIOS, you must either reset the CMOS battery (which requires opening the case) or contact the manufacturer. There is no software workaround.

What if I do not know my service tag or serial number?

Your service tag is usually printed on a sticker on the bottom of your computer or inside the case near the motherboard. Your serial number may also be on the original box or receipt. If you cannot find either, the manufacturer may still help you if you can provide other proof of purchase, such as an order number or credit card statement.

Is it legal to remove a BIOS password from someone else's computer?

No. Removing a BIOS password from a computer you do not own is unauthorized access and is illegal. This guide is for removing passwords from your own computers. If you have a work computer locked by your employer, contact your IT department.

Do I need to replace the CMOS battery after removing it?

No. The CMOS battery lasts many years — typically five to ten years or more. Removing it temporarily to reset the password does not wear it out. straightforward reinstall the same battery and it will continue working normally.