Generator Fuel Calculator
How long will your generator run?
Generator Fuel Consumption Calculator
How long will your generator run?
Formula
Runtime = Tank Size / Fuel per HourHow to Use
- 1Enter tank size — Input your generator fuel tank capacity in gallons.
- 2Set fuel consumption — Enter the rated fuel consumption at your expected load (check the manual).
- 3Choose load percentage — Select your estimated load — generators are most efficient at 50-75% load.
- 4Get runtime estimate — See how many hours your generator will run before refueling.
Frequently Asked Questions
How much fuel does a generator use per hour?
A typical 3500W portable generator uses 0.5-1.0 gallons per hour at 50% load. Larger generators consume proportionally more.
Is it bad to run a generator at full load?
Running at 100% load continuously increases fuel consumption and wear. Aim for 50-75% load for optimal efficiency and longevity.
How long will a 5-gallon gas can run a generator?
At 50% load on a typical 3500W generator, about 8-12 hours. Exact runtime depends on the generator model and load.
Can I use a generator during a power outage?
Yes, but NEVER run it indoors or in an enclosed space. Place it at least 20 feet from the house with exhaust pointing away.