Inverter Sizing Calculator

Enter your loads to estimate the inverter’s continuous kW, surge kVA, whether you need 120/240 V split-phase, and the estimated DC current at your battery voltage.

System & Policy

Battery/System voltage (V)

Used to estimate DC current draw at the inverter input.

Inverter efficiency (%)

For DC current estimate (higher = less current).

AC output

Choose split-phase if you have any 240 V loads (well pump, dryer, AC, EVSE).

Continuous headroom (%)

Margin on top of running watts (wiring/heat/future growth).

Starting profile

Controls how surges aggregate.

Target surge duration (s)

Many inverters can do 2× for 1–10 s; use this as a guide.

Loads

Name	Running (W)	Surge ×	240 V?

Tip: Resistive loads (toaster/kettle) ≈ surge×1. Motors often 2–7× unless soft-started.

Results

Continuous (kW)

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Surge (kVA)

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Suggested Configurations

Share / Save

Share link saves settings and loads. Also accepts L imports from other tools.