Generator Runtime Calculator
Estimate how long a generator runs on a full tank of fuel.
About the Generator Runtime Calculator
The Generator Runtime Calculator gives you a clear, instant answer to a question that usually means digging through tables or guessing — enter your numbers and read the result straight away.
A generator is the standby power solution for homes and businesses across Pakistan, and sizing it correctly avoids two expensive mistakes: buying one too small that overloads, or too large that wastes fuel. This Generator Runtime Calculator sizes your generator from your load requirements.
The calculation adds your running load and applies the standard safety margin — generators should run at 70–80% of capacity, never flat out — to arrive at the right kVA or kW rating.
Fuel consumption follows the load: a generator under light load burns less per hour but costs more per unit of useful power. Sizing it to your typical load, not your peak, balances cost and reliability.
Match the result to the generator's rated output (kVA) — convert kW to kVA by dividing by the power factor, typically 0.8 for single-phase generators used in Pakistani homes.
Use the Generator Runtime Calculator as often as you like — it is free, needs no account, and pairs well with the other calculators in this category for a fuller picture.
How to size a generator
- 1
Enter the total load of the appliances you must run during outages.
- 2
Read the recommended generator size in kW and kVA, updated live.
- 3
Choose a generator rated at or above the kVA figure.
Frequently Asked Questions
How long will my generator run?
Divide tank capacity by hourly consumption. A 20 L tank at 1.5 L/hour runs about 13 hours.
How do I convert kW to kVA for a generator?
Divide kW by the power factor — usually 0.8 for single-phase generators. So a 5 kW load needs a generator rated at about 6.25 kVA.
Should I size a generator for peak or typical load?
Size for the appliances you genuinely need during an outage, plus a 20–30% margin. Sizing for every appliance in the house makes the generator expensive to buy and wasteful on fuel.