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🧩 PC components · Power supply

PC Power Supply Wattage Calculator

Estimate PC PSU wattage from CPU, GPU and other components while allowing for transient loads and reserve headroom.

✓ Free calculator✓ No sign-up✓ Instant results

Calculation inputs

Change any value for an instant recalculation.

Use sustained/load power rather than TDP alone.
Use a reliable rated or measured board power.
Board, RAM, SSD, fans, USB devices.
Simplified estimate, not ATX 3.x certification.
Allow for expansion and operating conditions.
Calculation inputs are saved locally in your browser.

How is it calculated?

Sustained watts = CPU + GPU + other components. Estimated transient peak = CPU + GPU × (1 + transient allowance) + others. Add reserve and choose the next typical PSU rating. This is not certification of any particular PSU, and it does not check connectors, ATX transient requirements or power quality. PSU wattage is DC output rating, not wall input.

Frequently asked questions

Does the result guarantee PSU compatibility?

No. Check manufacturer recommendations, connectors, ATX 3.x requirements, quality and independent tests.

Does 80 PLUS increase rated PSU output?

No. Efficiency affects wall draw and heat, not the stated output power.

Equipment related to this calculation

Practical, non-promotional buying considerations. Future partner recommendations will be clearly disclosed.

ATX power supply

Check protections, GPU connectors, ATX standard and headroom for transient peaks.

Wall-power meter

Wall-power measurements help understand consumption but cannot replace transient PSU sizing.

Frequently asked questions

Is adding CPU and GPU TDP enough?

Not always. TDP may differ from transient power draw, and other components and headroom matter too.

Does this replace checking PSU connectors?

No. Check GPU power connectors, manufacturer requirements, ATX specification and case clearance before buying.