Undersized inverters trip on motor starts; oversized units waste money and idle draw. This inverter sizing calculator takes your peak load in watts and a safety margin percent to recommend a minimum inverter rating for planning.
Benefits
- Minimum W = peak load × (1 + margin ÷ 100).
- Default margin covers modest surge and future loads.
- Outputs a watt target before you shop continuous vs. peak specs.
How it works
- Sum steady-state watts for appliances on the inverter bus.
- Enter peak load W and a safety margin percent.
- Read minimum inverter size in watts—match to datasheet continuous rating.
FAQ
How does an inverter sizing calculator work?
Multiply peak load watts by one plus the margin fraction: inverter W = peak W × (1 + margin ÷ 100). Example: 1,800 W peak with 25% margin → 2,250 W minimum. Use running watts for steady loads; raise margin when fridges, pumps, or power tools start on the same bus.
What is a good safety margin for inverter sizing?
20–30% is common for mostly resistive loads. Motor-heavy rigs often need 35–50% margin—or a separate surge calculator—because compressors can draw 2–3× at startup. Document which loads can start together before finalizing the SKU.
Continuous watts vs. peak (surge) on the datasheet?
This calculator targets minimum continuous watts after margin. Inverter labels also list peak/surge watts for motor starts. Pick a unit whose surge rating covers your largest starting load even when continuous watts meet the calculated minimum.
Technical specifications
- Minimum inverter W = peak_W × (1 + margin% ÷ 100).
- Peak load = sum of simultaneous running watts.
- Motors may need extra surge headroom beyond margin %.
- Related: inverter-sizing, watts-to-amps, battery-bank-size, ups-runtime.