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Aviation calculators/Flight planning/Point of no return
FLIGHT PLANNING

Point of no return calculator

Estimate how far you can travel from departure and still return within usable endurance after setting aside the entered reserve.

Instant resultsGround speeds in knotsNo account needed

Route assumptions

Live calculation

Enter planned ground speeds for the two directions. Speeds are knots, distances nautical miles, and endurance hours.

kt
Toward the destination at the applicable flight condition.
kt
Back toward departure at the applicable flight condition.
h
Available flight time at your planned fuel-burn assumption.
h
Time held back; 0.75 h means 45 minutes.
NM
Optional; locates the point on the route diagram.
Use forecast winds and appropriate diversion performance to establish the two ground speeds. Calculate ground speed →

Your return limit.

LIVE RESULTS
Point of no return from departure231.8 NM

Maximum modeled distance for an out-and-back return with the entered reserve.

Time outbound to PNR1 h 56 min
Time to return2 h 19 min
Endurance after reserve4 h 15 min
THE METHOD

Balance time out and time back.

Safe endurance is total endurance minus the required reserve. At the point of no return, outbound flight time plus return flight time equals that safe endurance. The two directions can have different ground speeds.

The formulaTime outbound = safe endurance × GS back / (GS back + GS outbound) · Distance = time outbound × GS outbound

Ground speed must be positive in both directions. Knots and nautical miles produce times in hours. Calculations use full precision; displayed distances round to one decimal and times to the nearest minute.

WORKED EXAMPLE

A route in numbers.

With 5 h total endurance, 0.75 h reserve, 120 kt outbound and 100 kt returning, safe endurance is 4.25 h. PNR is 231.8 NM from departure: about 1 h 56 min outbound and 2 h 19 min back.

Method reference: CASA Part 141 sample operations manual, sections 2B5.2.3–2B5.2.4. This site applies its equations to a simplified route between departure and destination.

Explore the point of equal time calculator →

A few common questions

Is this a legal or operational fuel limit?+

No. The entered endurance and reserve are your own planning assumptions. Apply the current approved fuel policy and aircraft performance data.

Why does a slower return speed move the PNR closer?+

It takes longer to cover each nautical mile returning, so more of the usable endurance must be held for the return leg.

Understand the limits of this estimate.

Fuel burn, climb, descent, holding, alternate availability, weather changes and aircraft-specific reserves are not modeled. A PNR beyond the entered route distance does not establish that the destination is reachable or suitable. Verify current official information, required reserves and approved aircraft documentation.