Generator size calculator for Kerala homes
Tick what you need to keep running in a power cut and get an indicative kVA rating — sized for motor start-up, not just running load.
Mon–Sat, 9:00 AM – 7:00 PM ISTTick what you need to keep running in a power cut.
Add an appliance to size your set.
Indicative only — based on typical Kerala conditions, not a quote. We confirm the real figures at the free site assessment, which costs you nothing. Your actual figures depend on the real nameplate ratings of your appliances, how long they run, and how the changeover is arranged. Figures reviewed July 2026.
How this works
Most generator sizing goes wrong in the same place. You add up the running watts of everything you want to keep on, convert to kVA, and buy that machine. Then the first time the water pump kicks in against a loaded house, the set browns out or trips.
The reason is start-up surge. A motor — a pump, a fridge compressor, an air conditioner — draws several times its running current for a second or two as it starts. So this calculator checks two things independently and takes whichever is larger: the running load, discounted because you do not genuinely run the geyser, the oven and the iron at the same instant, and then given 20% headroom so the set is not pinned at 100%; and the worst realistic instant, which is everything already running while the single largest motor on your list starts. The diversity discount is deliberately not applied to that second check — discounting the worst case would defeat the whole point of testing for it.
The result is then rounded up to a set you can actually buy, because nobody sells a 7.3 kVA generator, and expressed in kVA at a 0.8 power factor, which is what a set is rated at. It is a starting point for a conversation, not a specification: the real answer depends on your duty cycle, your cable runs and how the changeover is arranged.
Common questions
- Why is the suggested generator bigger than my total watts?
- Two reasons, and both are deliberate. Motors briefly draw several times their running current at start-up, so the set has to swallow that surge while everything else is already running. And a generator held at 100% of its rating permanently wears out early and leaves nothing for the load you forgot to list. A set sized purely on the arithmetic sum of running watts is a set that trips.
- What is the difference between kW and kVA?
- kW is real power — the work actually done. kVA is apparent power, which is what a generator is rated at, and the two differ by the power factor. At a typical 0.8 power factor, a set delivering 8 kW is a 10 kVA machine. This calculator gives you kVA because that is the number on the machine you will be buying.
- Do I need a changeover switch?
- Yes — a generator must never be able to backfeed the grid. Beyond the safety and legal requirement, an automatic transfer arrangement is what makes backup power actually useful: it decides which circuits get picked up and how quickly, without anyone going outside in the rain to throw a switch. We designed exactly this around a 30 kVA set at Karuna Bhavan in Kottayam.
- Can you size a generator for a factory or a hotel rather than a house?
- Yes, and at that scale this calculator is the wrong tool — it is built around household appliance loads. For industrial and commercial sites we design around your actual duty cycle and the loads that genuinely cannot be lost, rather than around the whole connected load. We have specified up to a 150 kW backup set on a hotel and back-up around STP blowers where the process cannot stop. Just ask.
Our other free tools
Let's power your next project
Reach out for a consultation or a free site assessment.
Mon–Sat, 9:00 AM – 7:00 PM ISTDownload our brochure (PDF)Request a free assessment
No obligation · reply within 2 hours