Generator Runtime Calculator

Fuel burn is not proportional to load. GenRun uses a load-dependent curve, so a light load does not get you a wildly optimistic number of hours. No ads.

A generator's runtime is not a fixed number. It depends on how much load you put on it, and that changes every time someone plugs something in.

GenRun takes your generator's tank size and rated output, adds up the appliances you are running, and tells you how many hours the fuel in the tank is good for — and the clock time you will need to refuel.

A Live Activity puts the countdown on the Lock Screen and warns you before the tank runs dry, so the generator stops when you choose rather than in the middle of the night.

Fuel burn is not proportional to load. A generator at a quarter load wastes a large share of its fuel just spinning, so the app uses a load-dependent consumption curve rather than a flat litres-per-hour figure.

Log real refuels and the app learns your machine's actual burn rate, which drifts from the manufacturer's figure as an engine ages.

Petrol, diesel and LPG, in litres or gallons. Everything is an estimate to help you plan refuelling, not a guarantee. Never refuel a running or hot generator, and follow the manufacturer's instructions. All data stays on device and no sensor is required.