Speed Distance Time Calculator
Choose what you want to find, enter the other two values in any units, and get the answer instantly, plus your arrival time and the average speed over a multi-leg trip.
Multi-leg trip: average speed
Enter each leg's distance (in km) and driving time. Average speed = total distance ÷ total time.
| Leg | Distance | Time (h : m : s) | Speed |
|---|
How to use the Speed Distance Time Calculator
- Choose Speed, Distance or Time as the value to solve for.
- Enter the two known values and pick their units. Time is entered as hours, minutes and seconds.
- Read the answer in the green card and in every other unit below it.
- Set a departure time and any break minutes to see when you will arrive.
- For a trip with several legs, enter each leg's distance and time in the table to get the true average speed.
The speed, distance and time triangle
All three values are linked by one relationship, distance = speed × time. Rearranged:
- Speed = distance ÷ time
- Distance = speed × time
- Time = distance ÷ speed
The units must match: km/h with kilometers and hours, mph with miles and hours, m/s with meters and seconds. The calculator converts everything to meters and seconds internally, so you can mix a distance in miles with a speed in km/h.
Worked example: a 350 km drive at an average of 90 km/h takes 350 ÷ 90 = 3.889 h. The 0.889 h is 0.889 × 60 = 53.3 minutes, so the drive takes about 3 h 53 min 20 s. Leaving at 9:00 with a 30-minute break, you arrive at about 13:23.
Speed unit conversions
| Unit | km/h | mph | m/s | knots |
|---|---|---|---|---|
| 1 km/h | 1 | 0.6214 | 0.2778 | 0.5400 |
| 1 mph | 1.6093 | 1 | 0.4470 | 0.8690 |
| 1 m/s | 3.6 | 2.2369 | 1 | 1.9438 |
| 1 knot | 1.852 | 1.1508 | 0.5144 | 1 |
| 1 ft/s | 1.0973 | 0.6818 | 0.3048 | 0.5925 |
Travel time chart
How long common distances take at a steady speed (no stops):
| Distance | at 50 km/h (31 mph) | at 80 km/h (50 mph) | at 100 km/h (62 mph) | at 120 km/h (75 mph) |
|---|---|---|---|---|
| 50 km | 1:00 | 0:37:30 | 0:30 | 0:25 |
| 100 km | 2:00 | 1:15 | 1:00 | 0:50 |
| 250 km | 5:00 | 3:07:30 | 2:30 | 2:05 |
| 500 km | 10:00 | 6:15 | 5:00 | 4:10 |
Real journeys are slower than the steady-speed figure because of traffic, junctions and stops. For road trips, an average of 70–80% of the speed limit is a realistic planning figure.
Average speed over several legs
Average speed is total distance ÷ total time, never the simple average of the leg speeds. Example: 190 km in 2 h (95 km/h) followed by 70 km in 50 min (84 km/h) is 260 km in 2 h 50 min, an average of 91.76 km/h. Including a 20-minute stop between the legs drops the overall average to 82.1 km/h.
Speed and pace
Runners, walkers and cyclists often use pace, the time per kilometer or mile, instead of speed. Pace is simply the reciprocal of speed: 60 ÷ speed in km/h gives minutes per kilometer. 12 km/h is a 5:00 per km pace, and 10 km/h is 6:00 per km. When you solve for speed, the calculator also shows the pace per km or per mile for the chosen distance unit.
Frequently asked questions
What is the formula for speed, distance and time?
Distance = speed × time, speed = distance ÷ time and time = distance ÷ speed. Cover the value you want in the triangle (D on top, S and T below) and the remaining two show the calculation.
How long does it take to drive 100 km at 80 km/h?
Time = 100 ÷ 80 = 1.25 hours, which is 1 hour 15 minutes. Add any stops to get the total journey time.
How do I convert decimal hours to hours and minutes?
Keep the whole number as hours and multiply the decimal part by 60 for minutes. 2.4 hours is 2 hours and 0.4 × 60 = 24 minutes. The calculator does this for you and shows h:m:s.
Why isn't average speed the average of the leg speeds?
Average speed is total distance divided by total time. If you drive 60 km at 60 km/h and another 60 km at 30 km/h, you spend 1 h and 2 h, so the average is 120 ÷ 3 = 40 km/h, not 45 km/h. Slower legs take longer and so count for more.
What is a knot?
A knot is one nautical mile per hour. A nautical mile is exactly 1,852 meters, so 1 knot = 1.852 km/h ≈ 1.151 mph. Knots are used at sea and in aviation.
Does the arrival time account for time zones?
No. The arrival time is shown in the same local time as the departure time. If you cross a time zone, add or subtract the difference yourself.