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PCPartPicker PSU Calculator

Creator: Arya Ollivierra
Arya Ollivierra
Arya Ollivierra Mechanical & Aerospace Engineer

Mechanical and Aerospace Engineering student at Princeton University with minors in Materials Science and Sust...

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· Reviewed by Cierra Benson
Cierra Benson
Cierra Benson Electrical Engineer

Electrical Engineer with a Bachelor’s in Electrical Engineering and a minor in Mathematics. Experienced in sys...

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and Marshall Dantin, PE, SMIEEE
Marshall Dantin, PE, SMIEEE
Marshall Dantin, PE, SMIEEE Electrical Engineer

Marshall Dantin is a Power Systems Engineer with 15+ years of experience in the downstream and midstream petro...

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Use our PCPartPicker PSU calculator to estimate PC power use, add headroom, and find the right PSU wattage for your build.

Component Power Draw (Watts)
Use each component's rated/estimated power (CPU TDP, GPU TGP/TBP, or manufacturer specs). Leave any field blank or 0 if not applicable.
W
W
W
W
W
W
W
W
W
PSU Headroom
A safety margin added on top of the calculated system load — a common sizing choice (not a statement of PSU efficiency loss). 20% is typical; increase this if you plan to overclock or add components later.
%
PSU Sizing — Equation Reference
StepFormulaNotes
1. Total system loadP_system = CPU+GPU+Mobo+RAM+Storage+Fans+Cooling+Expansion+OtherSum of rated/estimated component power
2. Add headroomP_PSU = P_system × (1 + H)H typically 0.20 (20%)
3. Round to standard sizeNext available PSU wattage ≥ P_PSUe.g. 300/450/500/550/600/650/750/850/1000 W…
⚠ This is a common third-party PSU-sizing method (component sum + headroom), not a reproduction of PCPartPicker's own proprietary estimation algorithm. Always cross-check with your GPU manufacturer's recommended PSU wattage and consider overclocked/future-upgrade power needs.
19 views

A PCPartPicker PSU calculator helps you find a good PSU size. Our tool adds the power use of your PC parts. It then adds PSU headroom. This gives you a safe watt target.

You can use this tool before you buy a new power supply. It helps you avoid a PSU that's too small. It can also help you plan future PC upgrades.

Our calculator uses a simple power sum and headroom method. It doesn't copy PCPartPicker's private math. It shows a clear PSU watt estimate from your parts.

The tool checks CPU, GPU, board, RAM, drives, fans, cooling, cards, and other gear. It then adds your chosen headroom. The result helps you pick a PSU with enough power.

PCPartPicker PSU Formula

First, add the watts from all parts.

P_system = CPU + GPU + Motherboard + RAM + Storage + Fans + Cooling + Expansion + Other

Next, change headroom from a percent to a decimal.

H = Headroom ÷ 100

Then find the PSU need.

P_PSU = P_system × (1 + H)

The tool then rounds up to the first standard PSU size. That size must meet or beat the result.

This makes the PCPartPicker PSU calculator wattage easy to read. It also gives you a clear PCPartPicker PSU calculator watts result.

How to Use Online PCPartPicker PSU Calculator

  1. Enter your CPU power in watts.
  2. Enter your GPU power in watts.
  3. Add the watts for your board, RAM, and storage.
  4. Add fan, cooling, card, and other device power.
  5. Enter your headroom, then press calculate.

Empty part fields count as zero. Each power value must be zero or more. Headroom can range from 0% to 200%.

Example PCPartPicker PSU Calculation

Say your PC uses 125 W for the CPU. The GPU uses 250 W. The board uses 50 W. RAM uses 20 W. Storage uses 15 W. Fans use 10 W. Cooling uses 10 W. Other gear uses 20 W.

First, add the load.

P_system = 125 + 250 + 50 + 20 + 15 + 10 + 10 + 20

P_system = 500 W

Now use 20% headroom.

H = 20 ÷ 100 = 0.20

Next, find the PSU need.

P_PSU = 500 × (1 + 0.20)

P_PSU = 600 W

So, the minimum standard PSU size is 600 W. The next comfort size is 650 W.

Think of PSU headroom like extra room in a bag. You don't want to fill it to the top. Extra room can help when your PC needs more power.

Final Verdict

Our PCPartPicker PSU calculator makes PSU sizing quick and clear. It adds your part watts. Then it adds headroom. It also picks a standard PSU size.

A good PSU should meet your load. It should also leave room for peak use and future upgrades. Always check the maker's PSU guide for your GPU too.

FAQs

What is a PCPartPicker PSU calculator?

It's a tool that estimates the PSU watts your PC may need. It adds part power and headroom.

How does PCPartPicker PSU calculator wattage work?

It adds the watts for each part. Then it adds the headroom you enter.

What does the PCPartPicker PSU calculator watts result mean?

It shows the PSU power target after headroom. The tool also picks a standard PSU size.

What is the best PSU calculator?

The Best PSU calculator should use sound part data. It should also give a clear power target. Our tool uses a simple sum plus headroom method.

Why add PSU headroom?

Headroom gives your PSU extra room. It can help with high load and future part changes.

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