Solve for speed, distance, or time.
Pick what you want to find, enter the two values you know in any units, and get the answer instantly, plus the same speed in mph, km/h, m/s and knots, and your running pace per mile and kilometer.
What do you know?
Enter distance and time to find the average speed. The speed field shows the result.
What this speed means
Distance covered over time
How far you travel as the trip goes on
The same speed in every unit
Speed scorecard
Travel time for common distances
How long each distance takes at this exact speed. The last two rows are a marathon and a century ride.
| Distance | Travel time | Decimal hours | Pace /mile |
|---|
Speed, distance and time, explained
The Speed Formula
Speed equals distance divided by time. If you travel 100 miles in 1 hour and 30 minutes (1.5 hours), your average speed is 100 / 1.5 = 66.7 miles per hour. This calculator handles the unit conversion automatically.
Miles Per Hour vs Kilometers Per Hour
The US, UK, and a few other countries use miles per hour (mph). Most of the world uses kilometers per hour (km/h). To convert mph to km/h, multiply by 1.60934. For example, 60 mph equals about 96.6 km/h.
Average Speed vs Instantaneous Speed
This calculator computes average speed over the entire trip. Instantaneous speed (what your speedometer shows) varies moment to moment. Average speed accounts for stops, slowdowns, and speed changes throughout the journey.
Speed, Distance, and Time Relationships
The three variables are related: Speed = Distance / Time, Distance = Speed x Time, and Time = Distance / Speed. Knowing any two values lets you calculate the third. This is fundamental to trip planning and navigation.
Common questions
How do I calculate travel time from speed and distance?
Divide the distance by the speed. For example, 200 miles at 65 mph takes 200 / 65 = 3.08 hours, or about 3 hours and 5 minutes. Add time for stops, traffic, and weather delays.
What is the speed of sound and light?
The speed of sound in air at sea level is about 767 mph (1,235 km/h). The speed of light in a vacuum is approximately 186,282 miles per second or 670,616,629 mph. These are fundamental physical constants.
How accurate is average speed for trip planning?
Average speed gives a good estimate but does not account for traffic, stops, or varying speed limits. For highway trips, assume an average of 55-65 mph. For city driving, assume 25-35 mph. Mixed routes fall in between.
Can I enter the time in minutes only?
Yes. Enter 0 for hours and put the total time in minutes. For example, for a 45-minute trip, enter 0 hours and 45 minutes. The calculator converts everything to decimal hours for the calculation.
Results assume a constant average speed. Real trips vary with traffic, stops, terrain and weather. Use these figures for planning and add a margin for delays.