Generator (Genset) Sizing Calculator
Size prime and standby diesel, petrol, or gas generators to safely handle continuous household running load and high inductive motor starting surges.
Choose a home generator scenario
Use editable planning loads for common appliances. AC and pump startup demand varies significantly by model; example surge inputs are not equipment specifications.
Current running load: 2200 W. Estimated generator rating: 7.5 kVA. Verify starting transients and manufacturer's load ratings before selecting a generator.
Frequently Asked Questions
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Continue with another electricity or backup-planning tool.
Reference official efficiency and safety guidance from Bureau of Energy Efficiency and standards information from Bureau of Indian Standards.
Calculation Assumptions & Safety
Calculations are planning estimates using the displayed inputs and assumptions, not certified designs or verified provider bills. Actual runtime, generation, cost and wire requirements vary with equipment, installation and operating conditions. Confirm manufacturer specifications and current provider rules. Have a qualified electrician review wiring and backup installations.
Generator kVA for ACs, refrigerator and home loads
Two ACs drawing 1,200 W each, a 150 W fridge, 140 W of fans and 60 W of lights total 2,750 W running load. At power factor 0.8 and a planning 75% load level: 2.75 ÷ (0.8 × 0.75) ≈ 4.6 kVA, before motor-starting requirements.
How the calculation works
Running kVA ≈ running kW ÷ power factor. Generator selection must separately consider available load margin, compressor/motor startup demand and manufacturer prime/standby ratings.
Compare household scenarios
- 3 kW load at PF 0.8: 3.75 kVA before margin
- Two ACs + fridge + fans: illustrative running 2.75 kW
- Pump startup: verify motor starting current and transient voltage
Common questions
- What generator size runs two ACs?
- Read the actual electrical input and starting characteristics of each AC. Add the other simultaneous loads and check generator transient performance; cooling tonnage alone is insufficient.
- Can a 5 kVA generator run a 1.5 ton AC?
- Possibly, depending on compressor startup, other devices and the generator output rating. Verify both manufacturers’ specifications before selection.