Speed Calculator
Solve for speed, distance or time, or turn a running pace into speed and race finish times.
How it works
Choose what to solve for, then enter the other two values. Time is entered as hours, minutes and seconds.
Mix units freely, miles, kilometers, meters or feet for distance; mph, km/h, m/s, knots or ft/s for speed.
Pace mode converts a running or cycling pace per mile or km into speed, and predicts finish times for a 5K, 10K, half and full marathon at that pace.
Formula
speed
Where:
- distance
- = How far you travel
- time
- = How long it takes
Worked example
You drive 100 miles in 2 hours. And a runner holds 5:00 per km.
100 ÷ 2 = 50 mph, which is 80.4672 km/h. At 5:00/km, a 5K takes 5 × 5:00 = 25:00, and the speed is 12 km/h.
Optimizing Performance and Training
For athletes, the most useful tip is to understand the inverse relationship between speed and pace. Speed is how much distance you cover in a set time, while pace is how much time it takes to cover a set distance. When training for a marathon, use a calculator to determine the exact pace required to hit a specific finishing goal. For example, to break four hours, you need to maintain a consistent pace of roughly 9 minutes and 9 seconds per mile.
Misinterpreting Averages and Units
A common mistake is simply averaging two speeds to find the total average speed of a trip. If you drive 60 mph to a destination and 40 mph back, your average speed is actually 48 mph, not 50 mph, because you spend more time traveling at the slower speed. This concept, known as the harmonic mean, is a frequent source of error in logistics planning. Always calculate average speed by dividing the total distance by the total time spent.
Logistics and Urban Planning
Urban planners use speed calculations to design synchronized traffic light systems, known as 'green waves.' By calculating the average speed of vehicles on a specific corridor, they can time the lights to turn green just as the lead cars arrive, reducing congestion and emissions. Logistics managers use these same principles to optimize delivery routes, ensuring that drivers can reach their destinations within their legal driving hours while maximizing the efficiency of every shift they work.
Frequently asked questions
Speed is distance per time (like 12 km/h). Pace is time per distance (like 5:00 per km). Runners usually use pace.