Gaming Calculators
PC power supply wattage.
Add up what your CPU, graphics card and everything else can draw, add headroom, and round up to a common power supply size. Use the power figures from each part's spec sheet. Runs in your browser; nothing is sent or stored.
Inputs
Result
Fill the form and press Calculate.
Worked example
A 125 W CPU, a 285 W graphics card and 75 W for everything else add up to 485 W. With 30% headroom the target is 630.5 W, and the next common size up is a 650 W power supply, which would run at about 75% of its rating in a heavy load.
How it works
Target = (CPU + GPU + other) x (1 + headroom), rounded up to the next common size from 350 to 1600 W. The Power supply unit (computer) - Wikipedia article notes that the peak power draw of a 2010s CPU is often quoted at 1.5 times its TDP, and that the two big GPU vendors provide a PSU recommendation for each model that covers a whole hypothetical system. That is why this page uses your own figures rather than built-in part tables, and why the graphics card maker's recommendation should win when it is higher.
The 30% headroom, the 75 W allowance and the list of sizes are common rules of thumb, not published standards. Total draw is rarely the sum of every part's maximum at once, but transient spikes and PSU ageing are the reason people leave margin. Do not use this for safety-critical or rack/server power planning; check the actual power connectors and ratings of your parts and PSU.
Sources: Power supply unit (computer) - Wikipedia. Each opened 2026-10-08.
Planning guide only, not professional advice. Figures are estimates from the inputs you enter.
FAQ
What wattage PSU do I need for a gaming PC?
Add the CPU and graphics card power from their spec sheets, add 50 to 100 W for the rest, then add 20 to 40% headroom. The graphics card maker's recommended PSU is a good cross-check.
Is it bad to have a much bigger PSU than needed?
It costs more, but it will not damage your parts. A modest margin is usually enough.
What happens if my PSU is too small?
Under heavy load the PC may shut down, restart or crash, especially during graphics card power spikes. Replace it with a larger unit rather than lowering the load.
Is TDP the same as power draw?
Not exactly. TDP is a thermal design figure. Actual and peak draw can be higher, which is why peak CPU draw is often quoted at up to 1.5 times TDP for a conservative estimate.
Does this account for overclocking?
Only if you enter the higher power figures yourself. Overclocking can raise CPU and GPU draw well above the stock rating.