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All calculatorsMethodology

PC Wattage & PSU Load Calculator

Add entered component watts, compare a PSU rating with your DC load and headroom target, and estimate AC wall power using your scenario efficiency.

Interactive calculator · Method PC_WATTAGE-1.0 · Last reviewed: 2026-11-05

Calculate your scenario

Component DC load = Σ(quantity × entered DC watts).

Your inputs

Try an example

Default worked example. Edit the inputs to calculate your scenario.

Default worked example

Component DC load 450 W
Entered headroom 112.5 W
DC capacity target 562.5 W
Selected PSU utilization 69.230769%
Estimated AC wall power 500 W

450 W DC ÷ 90% efficiency = 500 W AC; 25% headroom applies to DC capacity only.

How to use the calculator

Replace each example row with label | quantity | DC watts each; add or remove lines as needed (up to 60 rows and 4,000 total characters). Enter your efficiency, headroom and optional rated DC output.

What the result means

Compare the entered component budget and DC target to your proposed PSU; wall draw is a separate AC estimate.

Formula and units

Component DC load = Σ(quantity × entered DC watts). AC wall watts = DC load ÷ (efficiency/100). DC target = DC load × (1 + headroom/100). Utilization = 100 × DC load ÷ PSU rated DC watts.

Worked examples

450 W example with a 650 W PSU: Optional PSU rated DC output (W; blank to omit): 650 W; Entered headroom (example): 25 %; Scenario efficiency (example): 90 %; Component rows — label | quantity | DC watts each (examples): CPU package limit | 1 | 125 GPU board power | 1 | 250 Other components | 1 | 75.
Example result: Component DC load: 450 W; Entered headroom: 112.5 W; DC capacity target: 562.5 W; Selected PSU utilization: 69.230769%; Estimated AC wall power: 500 W.

200 W example with 80% efficiency: Optional PSU rated DC output (W; blank to omit): 400 W; Entered headroom (example): 25 %; Scenario efficiency (example): 80 %; Component rows — label | quantity | DC watts each (examples): CPU package limit | 1 | 65 GPU board power | 1 | 100 Other components | 1 | 35.
Example result: Component DC load: 200 W; Entered headroom: 50 W; DC capacity target: 250 W; Selected PSU utilization: 50%; Estimated AC wall power: 250 W.

Limitations and common mistakes

All defaults are illustrative examples, not a component database or measured performance. CPU package limits, GPU board power and thermal design power are not measurements of complete PC draw. Efficiency varies with load. No connector, transient, rail, wiring or safe-fit certification is provided.

Dividing the headroom target by efficiency. A PSU rating is DC output; efficiency changes the AC input estimate.

Sources and assumptions

Method PC_WATTAGE-1.0; last formula review 2026-11-05. Sources and their supported claims. Calculation methodology.

Corsair: PSU: Efficiency Ratings Explained. Efficiency relates delivered DC power to AC input; it does not change the rated DC capacity target. Intel: PC Power Supply: How to Choose the Right One for You. Component budgeting and entered headroom are a planning comparison, not hardware compatibility certification.