Calculate speed, distance, or time. Enter any two values and the third is computed instantly. Supports metric, imperial, and nautical units.
Speed, Distance, and Time
Speed, distance, and time are linked by a single formula:
v = d / t
Where v is speed, d is distance, and t is time. Knowing any two values lets you find the third.
How to Use the Calculator
Enter values in any two fields. The third field updates instantly.
Examples:
- Distance 300 km + Time 3 h → Speed = 100 km/h
- Speed 60 mph + Time 2.5 h → Distance = 150 mi
- Distance 42.195 km + Speed 12 km/h → Time = 3 h 31 min 0 s
Change units at any time — the values convert automatically.
Common Speed References
| Object | Speed |
|---|
| Walking pace | 5 km/h (3.1 mph) |
| Cycling | 20–25 km/h (12–16 mph) |
| City speed limit | 50 km/h (31 mph) |
| Highway speed limit | 120 km/h (75 mph) |
| Commercial aircraft | 900 km/h (560 mph) |
| Speed of sound (sea level) | 1235 km/h (767 mph) |
Unit Conversions
| From | To | Multiply by |
|---|
| km/h | m/s | 0.2778 |
| mph | km/h | 1.6093 |
| knots | km/h | 1.852 |
| m/s | km/h | 3.6 |
Frequently Asked Questions
What is the formula for speed?
Speed equals distance divided by time: v = d / t. To find distance, rearrange to d = v × t. To find time, use t = d / v. Enter any two values into the calculator and it solves for the third automatically.
How do I convert km/h to mph?
Multiply km/h by 0.621371 to get mph. For example, 100 km/h × 0.621371 ≈ 62.14 mph. Alternatively, select your input unit as km/h and the output unit as mph in the calculator — the conversion happens automatically.
What is average speed?
Average speed is the total distance traveled divided by the total time taken. It does not account for changes in direction or speed along the way. For example, driving 300 km in 3 hours gives an average speed of 100 km/h.
What is a knot?
A knot (kn) is a unit of speed equal to one nautical mile per hour, or approximately 1.852 km/h (1.151 mph). It is used in maritime and aviation navigation.
How many meters per second is 100 km/h?
100 km/h equals 27.78 m/s. To convert km/h to m/s, divide by 3.6. So 100 ÷ 3.6 ≈ 27.78 m/s.
What units does this calculator support?
Distance: mm, cm, m, km, in, ft, yd, mi, nautical miles. Time: milliseconds, seconds, minutes, hours, days, weeks. Speed: m/s, km/h, mph, ft/s, knots. All combinations work — the calculator converts between unit systems automatically.