Inverter Size Calculator
Inverter rating for a given load, with the DC current it will draw at full load and on surge.
Results
Power
3600
W
Current
81.5
A
Current
163.0
A
Power
156.5
W
What this tool does
Motors, pumps and fridges draw two to four times their running power for a second when they start, so the inverter has to survive the surge rather than the average. The DC current matters just as much: 1800 W from a 24 V bank is over 80 amps, which needs serious cable.
Formula
inverter power = continuous load × starting factor
Variables
| Symbol | Meaning | Unit |
|---|---|---|
p | Power | W |
sf | Starting surge factor | — |
u | Voltage | V |
ef | Efficiency | % |
PS | Power | W |
IN | Current | A |
IS | Current | A |
PL | Power | W |
Worked example
- Power1800 W
- Starting surge factor2
- Voltage24 V
- Efficiency92 %
- Power3600 W
- Current81.5 A
- Current163.0 A
- Power156.5 W
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- Electrical installations are governed by national wiring rules. Cable sizing also depends on installation method, grouping, ambient temperature and protection devices, which this calculator does not evaluate.
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.