How Extra Fuel Reserve Calculator Works?
This tool works by adding a safety buffer percentage to the base fuel a trip needs. The result is the total gallons to carry.
Enter base fuel needed
Type the gallons the trip needs with no buffer. The default is 22 gallons (83.3 L).
Enter the buffer percentage
Type the safety margin. 10% suits paved routes, and 20% to 30% suits remote or off-road travel.
Read the total gallons
The tool returns base fuel plus the buffer.
Plan fuel storage
Check that the tank plus any approved cans holds the total.
Extra Fuel Reserve Calculator Formula
The formula is Total Fuel = Base Fuel × (1 + Buffer % ÷ 100).
Total Fuel = Base Fuel × (1 + Buffer ÷ 100)Formula variables
- Base Fuel
- Gallons needed for the trip at normal MPG.
- Buffer
- Safety margin as a percentage.
Worked example
- Base Fuel Needed: 22 gallons
- Safety Reserve Buffer %: 15%
- Buffer factor: 1 + (15 ÷ 100) = 1.15.
- Total fuel: 22 × 1.15 = 25.30 gallons (95.8 L).
Result: 25.30 (total gallons)
The 15% buffer adds 3.3 gallons (12.5 L) to the plan. Headwinds, soft sand, steep grades, and heavy loads each raise fuel use by 10% or more.
Extra Fuel Reserve Calculator Conversion Table
The table lists total gallons for 4 base fuel amounts at 4 buffer levels.
Rows: Base Fuel Needed (gallons). Columns: Safety Reserve Buffer % (%). Cells: total gallons.
| gallons | 5% | 10% | 15% | 25% |
|---|---|---|---|---|
| 10 gallons | 10.50 | 11.00 | 11.50 | 12.50 |
| 15 gallons | 15.75 | 16.50 | 17.25 | 18.75 |
| 22 gallons | 23.10 | 24.20 | 25.30 | 27.50 |
| 30 gallons | 31.50 | 33.00 | 34.50 | 37.50 |
A 30-gallon (113.6 L) base plan with a 25% buffer requires 37.5 gallons (142 L) in total.
What is Extra Fuel Reserve Calculator?
The Extra Fuel Reserve Calculator is a tool that adds a safety margin to the fuel a trip needs. The tool protects against running out in places without stations.
Fuel use on paper rarely matches fuel use on the road. Wind, terrain, idling, and wrong turns raise consumption, and a percentage buffer covers those changes.
The calculator suits overland travel, boating, aviation ground support, and any trip where refueling is hard.
What are the uses of Extra Fuel Reserve Calculator?
There are 4 main uses of the Extra Fuel Reserve Calculator: planning overland expeditions, fueling boats for open water, preparing emergency fuel supplies, and planning towing trips.
Planning overland expeditions
Travelers in deserts and backcountry carry a 20% to 30% reserve.
Fueling boats for open water
Boaters follow the common 1/3 out, 1/3 back, 1/3 reserve rule.
Preparing emergency fuel supplies
Households store fuel with a buffer for storm outages.
Planning towing trips
Drivers towing trailers add a buffer for uncertain MPG.
Need every metric in one place? Open the main MPG Cost Calculator or browse all 101 fuel calculators.