Specific range
How far each gallon of fuel takes you, through the air and over the ground, and the fuel each 100 takes, from your airspeed and fuel flow.
Planning and education aid. Not for primary navigation. Full disclaimer
Experimental: not yet fully verified. How results are checked
Each US gallon takes you 14.12 NM through the air; 100 NM takes 7.1 US gal.
- Fuel per 100 NM through the air
- Ground distance per gallon
- Fuel per 100 NM over the ground
Provenance
- Computed by
- aviation.performance.specific-range 1.0.1, core 0.1.0
- Model
- Specific range = speed ÷ fuel flow: through the air with TAS, over the ground with groundspeed (PHAK, aircraft performance). Fuel per 100 NM is its reciprocal times 100
- Accuracy
- Exact for the entered speed and flow; as good as the POH or gauge flow you enter. Wind changes the ground figure, not the air one
- Notes
- 1 shown with the answer
- Cites
- Federal Aviation Administration, Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: Specific range = speed ÷ fuel flow: through the air with TAS, over the ground with groundspeed (PHAK, aircraft performance). Fuel per 100 NM is its reciprocal times 100
Show your work
Fuel per 100 NM
100 × fuel flow ÷ TAS100 × 8.5 gal/h ÷ 120 kt= 7.1 US galAir distance per gallon
TAS ÷ fuel flow120 kt ÷ 8.5 gal/h= 14.12 NM/US gal
The same steps an agent gets from the MCP server with explain: true.
Accuracy: Exact for the entered speed and flow; as good as the POH or gauge flow you enter. Wind changes the ground figure, not the air one
Worked example: 120 kt true at 8.5 gal/h, 105 kt over the ground. Source: Worked from the definition: 120 ÷ 8.5 = 14.12 NM per gallon through the air, 105 ÷ 8.5 = 12.35 over the ground. It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.
You enter
- Fuel flow
- 8.5 gph
- Groundspeed
- 105 kt
- True airspeed
- 120 kt
You get
- Air distance per gallon
- 14.12 NM/US gal
- Fuel per 100 NM through the air
- 7.1 US gal
- Ground distance per gallon
- 12.35 NM/US gal
- Fuel per 100 NM over the ground
- 8.1 US gal
Review: Not yet independently reviewed by a flight instructor (CFI).
Last verified: 2026-09-19, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.1, core 0.1.0. See this tool in the verification report.
Changes
- 2026-09-23, fixed: Plain-number results in a fixed unit now show that unit: the battery current reads 9.7 A where it read 9.7, and decibels, gigabytes, pulses per square meter, grams per kilogram, nautical miles per gallon, hours, nanoteslas, and minutes now carry their units too. The numbers themselves do not change. Each tool's patch version went up. Changelog
Checked against: 8 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Federal Aviation Administration, FAA-H-8083-25C. Aircraft Performance chapter (range performance and specific range: distance per unit of fuel).
Terms
- NM: nautical mile
- A distance of exactly 1,852 meters, about one minute of latitude. Aviation and marine navigation measure distance in it. Source: ICAO Annex 5 Units of Measurement
- POH: Pilot's Operating Handbook
- The manufacturer's handbook for an aircraft: limitations, procedures, performance charts, and weight-and-balance data. Its numbers govern over any calculator. Source: Pilot's Handbook of Aeronautical Knowledge
Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.
NM — nautical mile
A distance of exactly 1,852 meters, about one minute of latitude. Aviation and marine navigation measure distance in it.
Source: ICAO Annex 5 Units of Measurement