Quick Answer
Speed-Distance-Time triangle: Speed = Distance ÷ Time · Distance = Speed × Time · Time = Distance ÷ Speed. Enter any two values and the calculator solves for the third.
What Is Speed & Distance?
Speed, distance, and time are locked in a simple triangular relationship, know any two, calculate the third. This comes up constantly: how long will a road trip take, how far does a train travel in a set time, what average speed did a runner maintain.
Speed is measured in km/h, distance in kilometres, and time in decimal hours. Time must be in decimal hours, 90 minutes = 1.5 hours. The calculator removes friction by letting you declare which value to solve for.
This relationship applies far beyond driving: runners track pace in min/km (pace is the inverse of speed); shipping companies calculate freight transit times from vessel speed and port distance; pilots use airspeed, wind correction, and ground distance together. Knowing any two values instantly unlocks the third, a universally useful relationship.
Unit consistency is the most common source of error in speed calculations. Speed stated in km/h must use distance in kilometres and time in hours. If you have minutes, divide by 60 first. If you have miles, convert to km (multiply by 1.60934) before using a km/h formula.
How to Use
- 1Select what you want to calculate: Speed, Distance, or Time.
- 2Enter the two known values.
- 3The result updates instantly.
Formula
Speed = Distance ÷ TimeDistance = Speed × TimeTime = Distance ÷ SpeedExample: A car travels 240 km in 3 hours, what is its average speed?
- Speed = Distance ÷ Time
- Speed = 240 ÷ 3
- Second example, how long does a 540 km train journey take at 90 km/h?
- Time = Distance ÷ Speed = 540 ÷ 90 = 6 hours
Tips & Things to Know
- This gives AVERAGE speed, real-world travel has stops and traffic.
- Time must be decimal hours: 90 minutes = 1.5 hours. Divide minutes by 60.
- Convert km/h to m/s: divide by 3.6. Convert mph to km/h: multiply by 1.60934.
- Reference speeds: walking ≈ 5 km/h; cycling ≈ 15–25 km/h; city driving ≈ 40–60 km/h; motorway ≈ 100–120 km/h; commercial aircraft ≈ 900 km/h.
- Running pace (min/km) and speed (km/h) are inverses: pace = 60 ÷ speed; speed = 60 ÷ pace. A 5:00 min/km pace = 12 km/h.
- Fuel planning: if your car does 12 km/litre and the trip is 360 km, you need 30 litres. Combine distance with this calculator to estimate both journey time and fuel cost.