Time, Speed and Distance Calculator

How it works

Time = distance ÷ groundspeed. Everything else on this page follows from that.

Reserves are not the target

The 45-minute figure shown is the IFR and night-VFR legal reserve; day VFR is 30 minutes. Both are the point below which you have broken a rule, not the point at which to start worrying. Pick a personal minimum — an hour is common — and treat reaching it as a decision, not a milestone.

Groundspeed, not airspeed

Use groundspeed here. If you only have true airspeed and a forecast wind, run the wind triangle first.