Speed Distance Time Calculator
Enter any two of the three values — speed, distance, or time — to instantly calculate the third. Works in km/h, mph, m/s, and any other unit combination.
The SDT Triangle
Three Formulas from One
Speed = Distance ÷ Time. Distance = Speed × Time. Time = Distance ÷ Speed. If speed is in km/h and distance in km, time comes out in hours. Always check unit consistency.
Unit Conversion Reference
1 m/s = 3.6 km/h = 2.237 mph. Speed of sound: ~343 m/s = 1,235 km/h. Speed of light: 299,792 km/s. A brisk walk = 5–6 km/h. Motorway driving = 110–130 km/h.
Real-World Application
Driving 350km at an average speed of 90 km/h: Time = 350 ÷ 90 = 3.89 hours = 3 hours 53 minutes. Allow extra time for fuel stops, traffic, and rest breaks — typically add 20–30% to pure drive time for realistic planning.
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