VFR Fuel Reserve Estimator
Estimate fuel required for a VFR helicopter flight: trip fuel + FAA-required reserve. Per 14 CFR 91.151(b), day VFR requires enough fuel to reach the destination plus 20 minutes at normal cruise. Night VFR requires destination plus 30 minutes. This calculator adds operational margin awareness against usable tank capacity.
Calculator inputs and results
Trip
Fuel
Per 14 CFR 91.151(b): Day VFR requires enough fuel to fly to the destination plus 20 minutes at normal cruise. Night VFR requires destination plus 30 minutes. This calculator does not account for warm-up, taxi, climb, descent, or alternate fuel - add an operational margin to the legal minimum.
How this calculator works
Ground speed = cruise TAS + wind component. Headwind is entered as a negative number; tailwind as positive. The calculator does not account for climb, descent, or maneuver fuel - it assumes pure cruise.
Trip fuel = trip time x fuel burn rate. Trip time = distance / ground speed.
Reserve fuel = (reserve minutes / 60) x fuel burn rate. FAA legal minimums are 20 min day VFR and 30 min night VFR. Many operators (especially Part 135) operate to higher internal standards - 45 min or 1 hour is common.
Default assumptions & sources
Every default value the calculator starts with, the realistic range you'd see in the field, and the source we used to set it.
| Input | Default | Typical range | Source |
|---|---|---|---|
| Distance | 100 nm | 10 to 500 | Great-circle distance from sectional or EFB |
| Cruise TAS | 110 kt | 60 to 180 | Aircraft POH cruise performance |
| Wind | 0 kt | -50 to +50 | Winds aloft forecast or FA0 product |
| Fuel burn | 15 gph | 5 to 100 | POH cruise fuel consumption at expected power setting |
| Reserve | 20 min | 10 to 60 | 14 CFR 91.151(b): 20 min day, 30 min night |
| Tank capacity | 50 gal | 20 to 300 | POH usable fuel capacity (not total) |
What's not modeled
The calculator covers the major cost and time line items. These additional factors apply in some cases but aren't included in the estimate:
- Start, taxi, run-up, hover, and climb fuel - all of these consume fuel above cruise burn rate. Add an operational margin to the legal minimum.
- Descent fuel - lower than cruise but not zero
- Maneuvering / external load / training profile - any time at higher than cruise power
- Alternate airport requirement - 14 CFR Part 135 IFR operations require additional alternate fuel; Part 91 VFR does not
- Fuel temperature density variation - cold soaked fuel is denser; the calculator assumes 6 lb/gal of avgas
Frequently asked questions
What is the FAA fuel reserve minimum for VFR helicopter flight?
Per 14 CFR 91.151(b): Day VFR requires enough fuel to fly to the destination plus 20 minutes at normal cruise consumption. Night VFR requires destination plus 30 minutes. This is the legal minimum - operators commonly carry 45-60 minutes of reserve for risk management.
#Is 91.151 the same for fixed-wing and helicopters?
No. 14 CFR 91.151(a) covers fixed-wing aircraft (30 min day, 45 min night). 91.151(b) covers rotorcraft and is more permissive (20 min day, 30 min night). The lower helicopter reserve reflects different operational profiles - shorter typical legs and more landing site flexibility.
#What about IFR fuel reserves?
IFR fuel reserves are addressed by 14 CFR 91.167. The basic IFR rule is: fly to destination + fly to most distant alternate + fly for 45 min at normal cruise. Specific Part 135 alternate requirements add additional layers.
#Should I plan to the legal minimum?
No. Legal minimums leave zero margin. Best practice is to plan to a personal minimum well above 14 CFR 91.151 - 30 min day / 45 min night is a common Part 91 personal minimum. Part 135 operators often standardize on 45 or 60 min minimum in their FAA-approved manual.
#Related guides & tools
This calculator provides estimates only. Actual aircraft performance and regulatory compliance vary by specific aircraft serial number, density altitude, gross weight, equipment installations, and operator's FAA-approved General Operations Manual / OpSpec. Always verify with primary sources: the FAA (faa.gov), 14 CFR (eCFR at ecfr.gov), your aircraft Rotorcraft Flight Manual (RFM) or Pilot Operating Handbook (POH), the relevant FAA Advisory Circular, and NTSB safety studies for the operational profile.