Speed Calculator

Calculate speed, distance, or time using v = d/t. Enter any two values to solve for the third. Includes unit converter, pace calculator, and real-world speed reference.

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v=d/t
Speed / Distance / Time Calculator

Select what you want to calculate, fill in the two known values, then click Calculate.

Hours
Minutes
Seconds
Result will appear here after calculating
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Speed Unit Converter

Enter any speed value to instantly convert it to all common units.

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pace
Running Pace Calculator

Calculate running pace (min/km or min/mile) from speed, or find speed from pace. Useful for marathon, 5K, and race planning.

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Speed Reference Table

Real-world speed examples. Click any row to use that speed in the calculator.

Object / Eventm/skm/hmphknots
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Speed, Distance & Time Guide
The 3 Formulas
Speed = Distance ÷ Time   (v = d / t)
Distance = Speed × Time   (d = v × t)
Time = Distance ÷ Speed   (t = d / v)

SI units: Speed in m/s, Distance in m, Time in seconds.
Common Speed Conversions
1 m/s = 3.6 km/h = 2.237 mph = 1.944 knots = 3.281 ft/s
1 km/h = 0.278 m/s = 0.621 mph = 0.540 knots
1 mph = 1.609 km/h = 0.447 m/s = 0.869 knots
1 knot = 1.852 km/h = 1.151 mph = 0.514 m/s
Speed of sound (air, 20°C) = 343 m/s = 1,235 km/h = 768 mph
Speed of light = 299,792,458 m/s = 299,792 km/s
Average vs Instantaneous Speed
Average speed = total distance / total time. This is what this calculator computes.
Instantaneous speed = speed at a specific moment in time (like a speedometer reading).

Example: A car travels 100 km in 1.5 hours. Average speed = 100 / 1.5 = 66.7 km/h, even though the car may have gone faster or slower at different points.
Mach Number
Mach number = object speed / speed of sound (343 m/s at sea level).
Mach 1 = 343 m/s = 1,235 km/h = 768 mph (speed of sound)
Mach 2 = 686 m/s = 2,470 km/h = 1,535 mph
Mach 5+ = hypersonic

The speed of sound varies with altitude and temperature — it is lower at high altitude where air is colder and thinner.