Speed, distance and time — solve for any one
These three quantities are locked together in one simple relationship, and if you know any two you can always find the third. That makes this calculator handy for planning trips, checking pace, working out arrival times, or answering homework questions.
How to use the calculator
Fill in any two of the three fields — distance, speed, and time — and leave the one you want to calculate blank. The calculator rearranges the formula and fills in the missing value.
The three arrangements
The core relationship is speed = distance ÷ time. Rearranged, distance = speed × time, and time = distance ÷ speed. For example, a 480 km trip driven at an average of 100 km/h takes 480 ÷ 100 = 4.8 hours, which is 4 hours and 48 minutes.
Getting the units right
Enter time as decimal hours, not hours and minutes — one and a half hours is 1.5, not 1.30. Keep your distance and speed units consistent (kilometres with km/h, or miles with mph). Remember that this calculates average speed over the whole journey; real trips include stops, traffic, and changing limits, so add a buffer when you are estimating a genuine arrival time.