150 km in 2 hours 30 minutes
Speed = distance ÷ duration
Thirty minutes is half an hour, so the duration is 2.5 hours. 150 ÷ 2.5 = 60 km/h.
Use total elapsed time if you want an average that includes stops.
Measurements and planning
Speed, Distance & Time Calculator
Enter two quantities to find the third, using average speed or a constant speed.
Calculate speed, distance, or elapsed duration
Average speed
Enter the known quantities, then select Calculate.
Calculation steps
Your inputs are calculated in your browser and are not sent to a server.
Three ways to use the same relationship
60 km/h for 2 hours 30 minutes
Distance = speed × duration
Multiply the speed by the duration in matching units: 60 × 2.5 = 150 km.
The speed must be constant, or the correct average for this interval.
150 km at an average of 60 km/h
Duration = distance ÷ speed
150 ÷ 60 = 2.5 hours, which is 2 hours 30 minutes. The remaining 0.5 hours is multiplied by 60.
This is a duration, rather than a time of day or an arrival prediction.
Units and rounding
Before calculating, the known quantities are converted to meters, seconds, and meters per second. One kilometer is exactly 1,000 meters; one international mile is exactly 1,609.344 meters; one hour is exactly 3,600 seconds. For example, 1 mph is exactly 0.44704 m/s.
Unit conversion and calculation use exact fractions, with no intermediate rounding. Decimal results are shown to your selected number of places, with 6 decimal places as the default. A displayed duration in hours, minutes, and seconds is rounded to the nearest whole second, independently of that setting.
Exact halfway values round up because all quantities here are nonnegative. An ≈ marks any rounded value. If a positive main result is so small that it rounds to zero, an additional message shows its exact fraction. Longer durations keep their total hours rather than wrapping after 24 hours.
Unit reference: NIST international mile conversion. This calculator uses the international mile, not the retired US survey mile.
Common questions
Should I include breaks or stops in the duration?
Include them when you want average speed over the whole trip: total distance divided by total elapsed time. Leave them out only when you specifically want average moving speed. If you use moving speed to estimate a trip duration, additional stops are not included automatically.
Is average speed the average of two speed readings?
Not generally. Average speed is total distance divided by total elapsed time. For example, 60 km at 60 km/h followed by 60 km at 30 km/h takes 3 hours in total: the average is 120 ÷ 3 = 40 km/h, rather than 45 km/h.
Can speed, distance, or duration be zero?
Zero distance over a positive duration produces zero average speed. Distance can be zero when speed or duration is zero. Calculating speed requires a duration greater than zero; calculating duration requires speed greater than zero, even if distance is zero. These rules avoid division by zero. Negative quantities are not accepted.
Why can I not enter 90 in the minutes field?
Minutes and seconds are each limited to whole numbers from 0 through 59. Enter 90 minutes as 1 hour and 30 minutes. Hours may range from 0 through 999,999,999. Blank time parts mean zero. Decimal speed and distance are supported, but the elapsed-time inputs use whole seconds.
Can this calculate arrival times or account for traffic?
No. This calculator uses elapsed duration and a constant or average speed. It has no route, traffic, location, time zone, calendar, or live speed data. For the interval between two clock times, use the Time Duration Calculator.
What do the decimal equivalents mean?
They describe the same quantity in another unit. For a duration, 2 hours 30 minutes is 2.5 total hours, 150 total minutes, or 9,000 total seconds. These are separate complete equivalents; they are not parts to add together. Each is rounded directly from the original result.