GenRun: Generator RuntimeGenRun: Generator Runtime
Hours of fuel left in the tank, and the clock time you will need to refill.
Download on the App Store
Screenshots
Features
Hours that change with the load
When the power drops in January the question is how long the tank will last, and that is never a fixed answer. Enter tank size and rated output, add what you are actually running, and GenRun estimates the hours you have left.
The time of the next refill
Beyond hours remaining, the app gives you the clock time the next refill comes due, so you can top up in daylight rather than out in the cold at 3 a.m.
Lock Screen countdown
A Live Activity keeps the countdown on your Lock Screen and warns you while fuel is still in the tank, so the unit shuts down on your schedule and not while the furnace fan is running and the house is cooling.
Consumption modelled by load
Rated hours divided by load percentage flatters a lightly loaded unit, because friction and cooling losses do not shrink when you unplug the kettle. GenRun uses a no-load loss plus a load-proportional term.
Learns your own unit
Record a few real refills and the app calculates what your machine actually burns. A generator that has sat in an unheated garage through several winters no longer matches its spec sheet.
Gas, diesel and propane
Litres or gallons, whichever you use. Propane is tracked by weight in kilograms, the way tanks are really filled. A home screen widget is included. iPhone only.
When the power goes out in January, the question is simple: how long will the tank last? The answer is not a fixed number. It moves every time somebody plugs something in.
GenRun takes your generator's tank size and rated output, adds up what you are actually running, and estimates how many hours of fuel you have left — plus the clock time you will need to refill.
THE SHORTCUT THAT OVERSELLS YOU
Most tools take the rated runtime and divide by load percentage. At a quarter load that arithmetic tells you the night is covered. It is not. An engine burns a large share of its fuel just turning over, and friction and cooling losses do not shrink when you unplug the kettle. On a typical portable unit the proportional method can overstate light-load runtime by more than 200% — 38 hours quoted where about 12 is the truth.
GenRun models consumption as a no-load loss plus a load-proportional term, which is how fuel is actually used.
A RANGE INSTEAD OF FALSE PRECISION
The biggest error is not in the math, it is in guessing what your appliances draw. GenRun gives you a range rather than one overconfident figure. A wide range means go check something; a narrow one means the plan holds.
COUNTDOWN ON THE LOCK SCREEN
A Live Activity keeps the countdown on your Lock Screen and warns you while fuel is still in the tank, so the generator shuts down when you choose — not at 3 a.m. with the furnace fan stopping and the house cooling fast.
IT LEARNS YOUR MACHINE
Log three or more real refills and GenRun figures out your unit's own burn rate. Engines drift from the manufacturer's spec as they age, and a generator that has sat in an unheated garage through a few winters is not the machine it was new.
FUELS AND UNITS
Gas, diesel and propane, in litres or gallons. Propane is tracked by weight in kilograms, the way tanks are actually filled, instead of being forced into a volume figure.
CARBON MONOXIDE
The first launch shows a full-screen carbon monoxide warning that cannot be skipped. Generators run outdoors only, well away from windows, doors and vents — never in an attached garage, a breezeway or under a deck, even with the door wide open. Cold weather makes the temptation worse and the risk higher.
PRACTICAL NOTES
Every figure is an estimate to help you plan a refill, not a guarantee. Check the tank yourself. Shut the engine off and let it cool before refuelling, and follow the manufacturer's instructions.
PRIVACY AND PRICE
No sensors, no account, no network connection. Everything stays on your iPhone, which matters when the internet is down along with the power. One payment, no subscription, no in-app purchases, no ads.
Useful through ice storms and winter outages, at the cottage or cabin, in an RV, on a job site, or anywhere a small engine is standing between you and a cold dark house.