Appliances & Utilities calculator
What Inverter Size Do I Need?
Use continuous ac load watts, peak/surge load watts, continuous headroom to find inverter continuous and peak power.
Enter your measurements
What Inverter Size Do I Need uses continuous ac load watts, peak/surge load watts, continuous headroom and the other configured measurements to return inverter continuous and peak power with a formula written specifically for this tool.
- Continuous AC load watts — Required
- Peak/surge load watts — Required
- Continuous headroom — Required
Inverter continuous and peak power
Enter the measurements above to calculate inverter continuous and peak power.
How the calculation works
V9 calculation: requiredContinuousWatts=continuousLoadWatts×(1+continuousHeadroom); minimumPeakWatts=peakLoadWatts. The result is reported as inverter continuous and peak power.
Worked example
Example: Continuous AC load watts = 500 W; Peak/surge load watts = 1000 W; Continuous headroom = 20%. Result: Required Continuous Watts = 600 W; Minimum Peak Watts = 1000 W.
Before you decide
The result is only as accurate as the measurements entered. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what inverter size do i need, the limiting result on this page is inverter continuous and peak power.
Direct measurement/geometry calculation. No external reference is required for the arithmetic itself; the result is derived only from the user-entered measurements and the formula stored in calculationLogicJson.
Frequently asked questions
What does the Inverter Size calculator tell me?
It returns inverter continuous and peak power from the measurements entered on this page. The calculation is specific to inverter size, so the result should be compared with the exact product or specification you are considering.
Which measurements should I take for inverter size?
Measure continuous ac load watts, peak/surge load watts, continuous headroom. Use clear, usable dimensions rather than nominal room or product labels.
Should I round the inverter continuous and peak power?
Keep the calculated value for comparison, then choose a real product that meets or stays within the returned inverter continuous and peak power while allowing for the clearances, tolerances or ratings shown by its manufacturer.