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Solar & Power

Inverter Sizing Calculator

Determine recommended inverter continuous and surge ratings.

Last validated: Pending

Inverter Sizing Calculator estimates the continuous and surge ratings needed to convert battery DC power into usable AC power for solar, RV, marine, cabin, or backup systems. Continuous load is the steady power required by appliances running at the same time, while surge load is the short startup demand from motors, compressors, pumps, and power supplies. Watts measure real power, VA measures apparent power, and power factor describes how much of the apparent power becomes useful work. Headroom is extra capacity added so the inverter is not operating at its limit. The tool helps avoid undersized inverters that trip under startup loads and oversized inverters that waste budget and idle power. Final sizing should still be checked against equipment manuals, waveform requirements, derating, wiring limits, and local electrical rules.

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Input Pattern

Enter values in the left panel, keep units explicit, run the calculation, then copy or share the result. Invalid fields are highlighted immediately.

Load Requirements

Total power used by all appliances running simultaneously.

Highest starting surge (motors, pumps, etc).

Recommended Sizing

Define your appliance loads

We'll help you pick the right inverter capacity.

How to use this tool

  1. Enter the simultaneous continuous load, maximum expected surge load, power factor, and desired headroom percentage.
  2. Use realistic startup loads for motors, compressors, pumps, and other appliances with high inrush current.
  3. Run the calculator and review the recommended continuous and surge inverter sizing.
  4. Check the recommendation against inverter datasheets, wiring limits, and local electrical requirements before installation.

Worked Example

Auto-generated from the tool's current default or entered inputs.

Example Inputs

Expected Outputs

Interpretation

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