Check the label on the power supply itself

The fastest way to find your power supply wattage is to look directly at the unit. Open your PC case and locate the power supply — it's usually a metal box in the bottom rear corner. On the side or back of the power supply, you'll find a label with specifications printed on it. Look for a line that says "Max Output" or straightforward "W" (watts). This number is your power supply's wattage rating.

If your PC is still under warranty or you're uncomfortable opening the case, you can also check the power supply without removing it. Many cases have a cutout or window that lets you see the label from outside. Shine a flashlight through the opening to read the specifications. The label is usually white or silver and printed in black text.

Key Takeaways

  • The power supply label inside your case shows the wattage — look for "Max Output" or "W" on the sticker.
  • If you can't open the case, check your PC's original documentation or the manufacturer's website using your model number.
  • Windows does not display power supply wattage in system settings, so software tools won't give you the official rating.
  • Third-party software like CPU-Z can estimate power draw, but this shows current usage, not your power supply's maximum capacity.

Find the wattage in your PC's documentation

If you have the original paperwork that came with your PC, the power supply wattage is usually listed in the specifications section. Look for a sheet labeled "System Specifications" or check the back of the box your computer came in. Prebuilt PCs from manufacturers like Dell, HP, Lenovo, or ASUS often print this information prominently.

If you've lost the physical documentation, visit the manufacturer's website and search for your PC model number. You can find your model number on a sticker on the back or bottom of your case. Enter it into the manufacturer's support page, and the specifications sheet will show the power supply wattage. This method works even for older PCs.

Use CPU-Z to see current power draw

CPU-Z is a free tool that shows detailed information about your PC's hardware, including an estimate of how much power your system is currently using. read it from cpuid.com, install it, and run the program. Open the "Power" tab to see your current power consumption in watts. This number changes depending on what you're doing — it will be higher when you're gaming or running demanding software, and lower when you're idle.

Keep in mind that CPU-Z shows your current power draw, not your power supply's maximum wattage rating. If your power supply is rated for 650 watts but you're only using 200 watts right now, CPU-Z will show 200 watts. This tool is useful for understanding how much power your system actually needs, but it won't tell you the official capacity of your power supply. To find that, you need to check the label or documentation.

Check the BIOS or UEFI settings

Some PC manufacturers display power supply information in the BIOS or UEFI firmware. Restart your computer and press the key to enter BIOS during startup — this is usually Delete, F2, F10, or F12, depending on your motherboard. The key appears briefly on the screen as your PC boots up.

Once you're in BIOS, look for a section called "System Information," "Main," or "Hardware Information." Not all systems display power supply wattage here, and the location varies by manufacturer. If you don't see it listed, exit BIOS by pressing Escape and try one of the other methods instead. Entering BIOS won't harm your PC, but avoid changing any settings unless you know what you're doing.

Estimate wattage based on your components

If you know what parts are inside your PC, you can estimate the power supply wattage by adding up the power requirements of each component. Your CPU and GPU are the biggest power consumers. Look up the TDP (Thermal Design Power) of your processor and graphics card — this is listed on the manufacturer's website or on the product box.

Add the TDP of your CPU and GPU, then add 50 to 100 watts for the rest of your system (motherboard, storage drives, fans, and other components). A good rule of thumb is to multiply this total by 1.3 to account for efficiency losses. For example, if your CPU uses 65 watts and your GPU uses 250 watts, your estimate would be (65 + 250 + 75) × 1.3 = about 520 watts. This gives you a rough idea, but it's not as accurate as checking the actual power supply label.

What to do if you can't find the wattage

If you've tried all the above methods and still can't find the wattage, contact the PC manufacturer's support team with your model number. They can look it up in their records and tell you the exact power supply rating. You can usually reach support through the manufacturer's website via chat, email, or phone.

As a last resort, if your power supply has failed and you need to replace it, take a photo of the label or bring the old unit to a computer repair shop. The technician can read the specifications and help you find a replacement with the same or higher wattage. Never guess at power supply wattage when replacing one — using a unit that's too weak can damage your components.

Frequently Asked Questions

Does Windows show power supply wattage in system settings?

No. Windows does not display your power supply's rated wattage anywhere in Settings or Device Manager. You must check the physical label on the power supply, your PC's documentation, or contact the manufacturer to find this information.

Is the wattage on the power supply label the same as what my PC actually uses?

No. The label shows the power supply's maximum capacity, not how much power your system is currently drawing. Your actual usage depends on what you're doing — gaming uses more power than browsing the web. CPU-Z can show you current usage, but the label shows the ceiling.

Can I use a power supply with higher wattage than my PC needs?

Yes. Using a higher-wattage power supply is safe and common. A 750-watt supply powering a system that only needs 500 watts will straightforward run at partial load. The downside is that higher-wattage supplies cost more, so there's no reason to buy one significantly larger than necessary.

What if the label on my power supply is worn or unreadable?

Try shining a bright flashlight at an angle across the label to make the text more visible. If that doesn't work, search online for your power supply's model number (also on the label) and the manufacturer's name. Most power supply makers publish spec sheets with the wattage listed.