Time-Speed-Distance Calculator
Solve for any one of time, groundspeed, or distance when you know the other two — the most fundamental calculation in flight planning. Time results are always shown as hours and minutes. Supports nautical miles, statute miles, kilometers, knots, MPH, and KPH.
Why This Matters to Pilots
Time-speed-distance is the foundation of all flight planning. Every leg of a cross-country — estimated time enroute, fuel required, and arrival time — begins with a TSD calculation.
TSD calculations use groundspeed, not airspeed. Airspeed is your speed through the air; groundspeed is your speed over the ground after wind is applied. A headwind lowers groundspeed and increases time enroute, while a tailwind does the opposite. Use the Wind Correction Angle Calculator to find groundspeed from your true airspeed and the wind.
The FAA Private Pilot knowledge exam includes time-speed-distance problems, and every checkride cross-country requires them.
The E6B flight computer solves TSD problems mechanically with its rotating wheel; this calculator replicates that same function digitally.
Limitations
This calculator uses constant speed and does not account for wind changes, altitude changes, or course deviations. For precise flight planning, use actual groundspeed from your GPS or flight plan.
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Frequently Asked Questions
This calculator is for educational and planning purposes only. Always refer to your aircraft's POH/AFM, current NOTAMs, and official weather briefings. No calculator is a substitute for pilot-in-command judgment or CFI guidance. Read our full Safety Disclaimer.
Last reviewed: July 2026
Time, Speed, and Distance in Depth
Time, speed, and distance form the most fundamental relationship in navigation: know any two and you can find the third. Every estimated time of arrival, every checkpoint timing, and every groundspeed check in flight rests on this simple proportion. Because it is so basic, it is also the calculation pilots perform most often, both in preflight planning and continuously in the cockpit.
The practical power of the relationship is that it lets you verify your progress against your plan in real time. By timing the distance between two known points you compute your actual groundspeed, and from that you can revise your arrival time and, crucially, your fuel picture. A pilot fluent in time-speed-distance is never surprised by where the aircraft actually is.
Step-by-Step: How the Calculation Works
The three forms of the relationship are distance = speed × time, speed = distance / time, and time = distance / speed, with speed here meaning groundspeed. The only discipline required is consistent units: if speed is in knots (nautical miles per hour), distance must be in nautical miles and time in hours, converting minutes to fractions of an hour as needed.
In flight, the most useful form is computing groundspeed from a timed distance. Note the time to cover a known distance between two checkpoints, divide the distance by that time in hours, and you have your actual groundspeed — which then feeds an updated arrival estimate and a fuel check. The calculator handles the unit conversions so you can focus on the decision the number drives.
More Worked Examples
Example 1 — Arrival time
You have 150 nautical miles remaining at a groundspeed of 125 knots. Time = 150 / 125 = 1.2 hours, or 1 hour 12 minutes. Added to the current time, that gives your estimated arrival, which you can pass to flight following or use to plan a fuel stop.
Example 2 — Groundspeed check
Two checkpoints are 20 nautical miles apart and you cover the distance in 9 minutes (0.15 hour). Groundspeed = 20 / 0.15 = 133 knots, faster than the 120 knots planned, meaning a tailwind is helping and your arrival will be earlier and your fuel burn to destination lower than planned.
Pilot Decision-Making Context
Time-speed-distance checks are the pilot's early-warning system. If a groundspeed check reveals a strong headwind, you learn early that the flight will take longer and burn more fuel than planned, giving you time to add a fuel stop or divert while options are still plentiful. The same check catches a navigation error before it compounds.
The relationship also disciplines pre-takeoff planning. Breaking a route into legs with computed times lets you build a flight log against which to compare actual progress, turning navigation from guesswork into a series of confirmable predictions. When reality and plan diverge, you know immediately and can act.
More Questions Answered
Do I use airspeed or groundspeed in these calculations?
Groundspeed. Time and distance over the ground depend on how fast you move relative to the ground, which differs from airspeed by the wind component along your course.
How do I handle minutes versus hours?
Convert minutes to a fraction of an hour by dividing by 60. Nine minutes is 0.15 hour, which keeps the units consistent with a groundspeed expressed per hour.
Why does my ETA keep changing in flight?
Because groundspeed changes as winds shift along the route. Recomputing time from your current groundspeed at each checkpoint keeps the arrival estimate accurate.
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