Inverter Size Calculator: What VA Inverter Do I Need?
List the appliances you want on backup (or enter the total watts). You get the load in VA, the recommended inverter size and the usual battery voltage for it.
- Nothing you type is stored
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- No signup
Recommended inverter
800VA
- Total load
- 454 W
- Load in VA
- 568 VA
- With margin
- 709 VA
- Usual battery voltage
- 12 V
Estimate only. Real results depend on your equipment, its age and conditions.
Motors (fridge, pump, mixer) need extra starting power; choose a sine-wave inverter rated for them.
Show working
- 454 W ÷ 0.8 = 568 VA
- 568 × 1.25 = 709 VA → 800 VA
How to use
- List appliances as “name, watts, how many”, or enter the total watts.
- Keep power factor 0.8 and a 25% margin, or adjust them.
- Read the recommended inverter VA and battery voltage.
Good to know
Inverter VA = total watts ÷ power factor × (1 + margin). Home inverters are rated in VA; at a typical power factor of 0.8 a 900 VA inverter supplies about 720 W. The 25% margin covers small surges and keeps the inverter from running at its limit.
Motors (fridge, pump, mixer, cooler) draw 3–6 times their running watts for a moment when they start. If you put them on backup, choose a bigger inverter or a sine-wave model rated for motor loads. ACs, geysers, irons and heaters are usually kept off home inverters.
Rule of thumb for battery voltage: up to about 1,100 VA uses one 12 V battery, 1,500–2,500 VA uses 24 V (two batteries), and bigger systems 48 V. Use the Battery capacity calculator to size the Ah for your backup hours.
Questions
Which inverter for 3 fans, 6 lights and a TV?
About 225 + 54 + 100 = 379 W; ÷ 0.8 × 1.25 = 592 VA, so a 600–700 VA inverter.
What is the difference between VA and watts?
VA = volts × amps. Watts = VA × power factor. Inverters are sold in VA.
Can my inverter run a fridge?
Usually yes on a sine-wave inverter of 800 VA or more, because of the starting surge. Check the inverter’s motor-load rating.
Can I run an AC on a home inverter?
Not on a typical 900–1,500 VA unit. ACs need large inverters and battery banks or solar hybrid systems.
Sine wave or square wave?
Pure sine wave is better for fans, fridges and electronics: quieter and cooler running.