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Fuel Reserve Requirement Calculator

Work out fuel reserve requirement instantly with clear inputs, formula shown and shareable results.

About Fuel Reserve Requirement Calculator

Reserve fuel is built up from separate blocks: fuel to fly to the alternate, a final reserve to hold at 1,500 ft over the alternate (30 minutes is the usual figure for turbine aircraft), and a contingency percentage on trip fuel to cover forecast error. All three are converted from time to quantity using the cruise burn rate.

Formula

Reserve fuel

Reserve = burn x (alternate min + final reserve min)/60 + contingency% x trip fuel

Worked example

With the default values below, Fuel Reserve Requirement Calculator returns Total reserve fuel required of 204.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Cruise fuel burn
180 per hour
Diversion time to alternate
35 min
Final reserve
30 min
Contingency on trip fuel
5 %

Results

Total reserve fuel required
204.00
Alternate fuel
105.00
Final reserve fuel
90.00
Contingency fuel (per hour of trip)
9.00

Step by step

  1. 1Values used
  2. 2Reserve fuel
  3. 3Total reserve fuel required= 204.00
  4. 4Alternate fuel= 105.00
  5. 5Final reserve fuel= 90.00
  6. 6Contingency fuel (per hour of trip)= 9.00

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

Frequently Asked Questions

Is 30 minutes always the final reserve?

It is the common turbine figure at holding speed. Piston aircraft VFR rules often require 30 minutes day and 45 minutes night; always check the applicable regulation.

Does contingency apply to reserve fuel too?

No. Contingency is a percentage of trip fuel only, and it is the block most commonly reduced by in-flight re-planning.

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