Inverter / IPS Size Calculator
IPS size = your load × 1.2 safety margin ÷ 0.8 power factor, rounded up to a standard size. A typical home load of about 500–600W needs a 1000VA IPS. Add your appliances below — surge appliances like fridges and pumps are flagged automatically.
- 1
- 2
- 3
- What do you use at home?
What do you use at home?
Pick your appliances — we'll fill in typical power for each. You can adjust everything later.
Quick start templates
Popular
Your appliances
No appliances yet
Add a few appliances above — or use a template to get started faster.
Total load
0 W
Daily energy
0 Wh
Worked example
A typical family setup — 2 ceiling fans, 4 LED bulbs, 1 TV, 1 fridge, 1 router and 4 CCTV cameras — runs at about 580W. With the safety margin and power factor applied, that needs a 1000VA IPS. The fridge's starting surge means a good surge rating matters, which the calculator warns about.
Common mistakes
- Buying an IPS whose VA number equals your load in watts — a 1000VA IPS is not a 1000W IPS for typical loads.
- Ignoring surge: fridges, water pumps and ACs draw 3–4× their running power for a moment at startup.
- Forgetting one appliance when adding up the load — routers and CCTV cameras run 24 hours and add up quickly.
- Sizing for everything at once when you only need essentials on backup — running the whole house doubles the cost.
Frequently asked questions
How many watts can a 1000VA IPS run?
About 800W of typical home load (1000VA × 0.8 power factor). That comfortably covers fans, lights, TV, router and CCTV together — roughly 3 fans, 5 LED bulbs, 1 TV and a router. For resistive loads like bulbs and heaters it can go closer to 1000W.
Can a 1000VA IPS run a refrigerator?
A fridge alone, yes — most run at 150–250W. But its compressor needs 3–4× that for a moment when it starts, so the IPS must have a good surge rating, and you shouldn't load it with much else at the same time. The calculator flags this automatically when you add a fridge.
IPS, inverter or UPS — which one do I need?
For keeping fans, lights, TV and a fridge running for hours during load-shedding, you need an IPS or inverter with a battery — that's what this tool sizes. A UPS is for short protection (seconds to minutes) of a computer or router, and is sized separately.
Why is the recommended IPS bigger than my total load?
Three honest reasons: the power factor (the VA rating is always larger than usable watts), a safety margin so the unit isn't running at its limit all the time, and starting surge from fridges, pumps and ACs. A size that exactly equals your load would struggle in real life.