Boat fuel and range calculator
Plan a run with confidence. Enter your usable tank size, cruise speed and fuel burn to see safe range with a reserve, how many hours you can run, and what a specific trip will cost in fuel.
Safe range at this speed
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Why the speed you choose changes everything
Fuel burn rises much faster than speed. A planing yacht that burns 30 gallons per hour at 20 knots may burn 4 or 5 gallons per hour at 8 knots, which can triple its range. Trawlers live at displacement speed for exactly this reason.
Use real numbers from your engine displays or a published boat test when you can. Builders often quote best case figures with light loads and clean bottoms.
The one third rule and other reserves
Many skippers plan with a third of the fuel for the outbound leg, a third for the return and a third in reserve, especially offshore. For coastal hops with fuel docks along the way, a 10 to 20 percent reserve is common. Rough water, headwinds and a fouled bottom all cut range, so build in more margin than you think you need.
- Account for unusable fuel at the bottom of the tanks
- Generator run time burns fuel too
- Range drops sharply in head seas
Frequently asked questions
How do I calculate boat range?
Divide usable fuel by gallons per hour to get hours of running, then multiply by cruise speed in knots. Subtract a safety reserve.
What is a good fuel economy for a yacht?
Displacement trawlers often achieve 2 to 5 nautical miles per gallon, while planing motor yachts commonly run between 0.3 and 1 nautical mile per gallon at cruise.
How much reserve fuel should I keep?
Offshore, plan to keep about a third in reserve. On protected coastal routes with frequent fuel docks, 10 to 20 percent is a common minimum.