Boat Fuel Cost Calculator (Distance, Speed, Fuel Burn, Price)

Estimate fuel use and fuel cost for a fishing trip from distance, speed, fuel burn, and price.

Account for wind, waves, detours, and idling with adjustment factors, and combine round trips or multiple legs in one calculation.

Enter any two values per leg and the third is calculated automatically
Supports both L/h and L/nm fuel-burn inputs
Share multi-leg conditions by URL

How to Use

  1. Choose the distance unit (nm or km) and the fuel-burn unit (L/h or L/nm), then use a preset if it helps you start faster.
  2. For each leg, enter any two of distance, speed, and time, and let the tool calculate the remaining field.
  3. Enter fuel burn, fuel price, and idle time, then adjust the safety factor and idle factor if needed.
  4. Review the estimated fuel use, fuel cost, and per-leg breakdown, then copy a share URL when you want to reuse the same conditions.

Examples

Coastal round trip (nm / kt, L/h)

Input

Port -> Fishing ground 18nm / 12kt
Fishing ground -> Port 18nm / 11kt
Fuel burn 20L/h
Fuel price 155JPY/L
Idle time 35 min
Safety factor 1.15
Idle factor 0.30

Output

Estimated fuel use 76.2L
Estimated fuel cost JPY 11,805

Lake route (km / km/h, L/nm)

Input

Outbound 12km / 24km/h
Return 12km / 22km/h
Fuel burn 1.2L/nm
Fuel price 160JPY/L
Idle time 20 min
Safety factor 1.10
Idle factor 0.30

Output

Estimated fuel use 18.7L
Estimated fuel cost JPY 2,999

With catch weight

Input

Same conditions as Example 1
Catch weight 120kg

Output

Cost per kg JPY 98/kg

Glossary

nm

A nautical mile. 1nm equals 1.852km.

kt

A knot. 1kt means 1 nautical mile per hour.

L/h

Fuel use per hour of running time.

L/nm

Fuel use per nautical mile. If you enter distance in km, the tool converts it internally to nm first.

Safety factor

A multiplier used to cover wind, waves, detours, and handling losses conservatively.

Formulas

  • Time = distance / speed
  • Speed = distance / time
  • Distance = speed x time
  • Running fuel (L/h mode) = fuel burn x total travel time
  • Running fuel (L/nm mode) = fuel burn x total distance in nm
  • Total fuel = (running fuel + idling fuel) x safety factor

FAQ

Do wind and wave conditions usually increase fuel use?

Often yes. Use the safety factor to build in a conservative allowance. A rough rule of thumb is Calm 1.05 / Normal 1.15 / Rough 1.30, but adjust it for your own vessel and conditions.

Which fuel-burn unit should I use?

Use L/h when your fuel data is time-based, and use L/nm when your fuel data is distance-based.

Can I calculate round trips or multiple routes?

Yes. Add as many legs as you need, or use the same-distance return-leg shortcut when the outbound and return distances are the same.

How is idling fuel handled?

It is estimated as a ratio of running fuel burn per hour. In L/nm mode, the tool derives an L/h equivalent from the weighted average speed.

Can I use this tool globally?

Yes. The page is designed for multilingual use, unit switching, locale-aware number formatting, and RTL layouts. Currency display is fixed to JPY in version 1.

Important Notes

  • Actual fuel burn can change sharply with wind, waves, current, payload, hull condition, RPM, and handling.
  • This tool is only an estimate. Increase the safety factor if you want a more conservative result.
  • If you have measured values for your own vessel or engine in L/h or L/nm, those values will be more reliable than presets.
  • Currency display is fixed to JPY in the first version. Even outside Japan, enter fuel price as JPY per liter.

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