Boat Fuel Range Calculator
Fill in the values and the answer updates as you type.
How the Boat Fuel Range Calculator works
Usable fuel = tank size × usable percentage, since the last part of a tank often cannot be drawn. Fuel to burn = usable fuel × (1 − reserve share). Endurance = fuel to burn ÷ burn rate, and range = endurance × speed. The default reserve of 33% follows the old rule of thirds: one third out, one third back, one third spare. Any fuel unit works if tank size and burn rate use the same unit. Current, waves, and wind change the real burn, so check it on the water. Example: with Fuel tank size 100 gal, Usable fuel 90 %, Fuel burn at cruise 12 gal/h, Cruising speed 22 kt, and Reserve to keep 33 %, the result is Range with reserve kept (NM) = 111; Endurance with reserve kept (hours) = 5; Fuel you plan to burn = 60.3.
Inputs and results
The Boat Fuel Range Calculator takes 5 inputs and gives 6 results.
What you enter
- Fuel tank size (gal) — starts at 100.
- Usable fuel (%) — starts at 90.
- Fuel burn at cruise (gal/h) — starts at 12.
- Cruising speed (kt) — starts at 22.
- Reserve to keep (%) — starts at 33.
What you get
- Range with reserve kept (NM)
- Endurance with reserve kept (hours)
- Fuel you plan to burn
- Fuel economy (NM per unit)
- Safe out-and-back radius (NM)
- Range with no reserve (NM)
Example: Boat Fuel Range Calculator with the starting values
With fuel tank size 100 gal, usable fuel 90 %, fuel burn at cruise 12 gal/h, cruising speed 22 kt and reserve to keep 33 %, the calculator returns:
| Range with reserve kept (NM) | 111 |
|---|---|
| Endurance with reserve kept (hours) | 5 |
| Fuel you plan to burn | 60.3 |
| Fuel economy (NM per unit) | 1.83 |
| Safe out-and-back radius (NM) | 55 |
| Range with no reserve (NM) | 165 |
Change any value above and the results update straight away.
Boat Fuel Range Calculator FAQ
How do I use the Boat Fuel Range Calculator?
Enter fuel tank size, usable fuel, fuel burn at cruise and cruising speed in the fields, then read range with reserve kept (nm), endurance with reserve kept (hours), fuel you plan to burn and fuel economy (nm per unit) in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Boat Fuel Range Calculator calculate?
Range and endurance of a boat while keeping a fuel reserve. It returns range with reserve kept (nm), endurance with reserve kept (hours), fuel you plan to burn and fuel economy (nm per unit) from the 5 values you provide.
What values does the Boat Fuel Range Calculator start with?
It opens with fuel tank size 100 gal, usable fuel 90 %, fuel burn at cruise 12 gal/h and cruising speed 22 kt so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Boat Fuel Range Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Boat Fuel Range Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.