Fuel Endurance + Reserve Calculator

Input Pattern

Enter values in the left panel, keep units explicit, run the calculation, then copy or share the result. Invalid fields are highlighted immediately.

How to use this tool

1. Enter usable fuel onboard, burn rate, reserve percentage, and cruise speed.
2. Run the calculation to compute reserve fuel and trip-usable fuel.
3. Review endurance and range outputs and verify they match route plus contingency.

Worked example

Checking fuel range with reserve

• Usable fuel: 400 L
• Burn rate: 40 L/h
• Reserve: 25%
• Cruise speed: 8 kn

Result: The calculator separates reserve fuel from trip-usable fuel, then estimates endurance hours and range.

Compare the range with planned route distance plus weather, traffic, diversion, and holding contingencies.

How to interpret the result

• Reserve fuel is intentionally excluded from planned trip fuel.
• Endurance assumes the entered burn rate remains constant.
• Range changes quickly with speed, sea state, current, load, hull condition, and generator or hotel loads.
• Conservative reserve policy is important when diversion options are limited.

Common mistakes

• Planning range from total fuel instead of trip-usable fuel after reserve.
• Using a calm-water burn rate for rough-weather or adverse-current passages.
• Forgetting generator, heating, auxiliary, or maneuvering fuel use.
• Treating calculated range as a promise instead of a planning estimate.

FAQ

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