How to Use This Speed Calculator
This calculator solves for speed, distance, or time when you know any two of the three values. Select what you want to calculate, enter the two known values with their units, and the result is displayed instantly. The calculator also shows your running or walking pace in minutes per kilometer or minutes per mile.
Steps:
- Select what to solve for: Speed, Distance, or Time
- Enter the two known values (with appropriate units)
- View the result along with all three values summarized and your pace
Speed, Distance, and Time Relationship
Speed, distance, and time are related by a simple triangle formula. If you know any two values, you can calculate the third. The three forms of the equation are:
- Speed = Distance ÷ Time
- Distance = Speed × Time
- Time = Distance ÷ Speed
For example, if you drive 300 miles in 5 hours, your average speed is 300 ÷ 5 = 60 mph. If you run at 8 mph for 30 minutes, you cover 8 × 0.5 = 4 miles.
Speed Unit Conversions
Speed can be expressed in many different units depending on the context. This calculator supports five common speed units and allows you to switch between them instantly.
| Unit | Full Name | Used In | 1 unit in m/s |
|---|---|---|---|
| mph | Miles per hour | US, UK (roads) | 0.44704 |
| km/h | Kilometers per hour | Most countries (roads) | 0.27778 |
| m/s | Meters per second | Physics, science | 1 |
| knots | Nautical miles per hour | Aviation, maritime | 0.51444 |
| ft/s | Feet per second | US engineering | 0.3048 |
Quick reference: 1 mph ≈ 1.609 km/h ≈ 0.868 knots. 1 km/h ≈ 0.621 mph. 1 knot = 1.15078 mph.
Understanding Pace
Pace is the inverse of speed and is commonly used in running and walking. Instead of expressing how far you go in a given time (speed), pace expresses how long it takes to cover a given distance. For example, a pace of 5:00 min/km means it takes 5 minutes to cover 1 kilometer.
Converting speed to pace:If you run at 10 km/h, your pace is 60 ÷ 10 = 6:00 min/km. For imperial, 6 mph corresponds to a pace of 60 ÷ 6 = 10:00 min/mile.
| Speed (km/h) | Pace (min/km) | Pace (min/mile) |
|---|---|---|
| 6 | 10:00 | 16:06 |
| 8 | 7:30 | 12:04 |
| 10 | 6:00 | 9:39 |
| 12 | 5:00 | 8:03 |
| 15 | 4:00 | 6:26 |
Real-World Applications
- Running and fitness: Track your pace, plan race times, and set training goals.
- Driving and travel: Estimate arrival times, plan rest stops, and calculate fuel needs for a trip.
- Aviation and maritime: Calculate flight times, fuel consumption, and navigate using knots.
- Physics and engineering: Determine velocities, analyze motion, and solve kinematics problems.
- Sports analytics: Measure player speed, ball velocity, and compare athletic performance across events.
Frequently Asked Questions
What is the difference between speed and velocity?
Speed is a scalar quantity (magnitude only) that measures how fast something moves. Velocity is a vector quantity that includes both speed and direction. For example, 60 mph is a speed, while 60 mph north is a velocity. This calculator deals with speed.
How do I calculate average speed for a trip with multiple segments?
Average speed is total distance divided by total time — not the average of individual speeds. If you drive 60 mph for 1 hour and 30 mph for 1 hour, your average speed is (60 + 30) ÷ 2 = 45 mph (since both segments took equal time). But if you drive 60 mph for 60 miles and 30 mph for 60 miles, the average is 120 miles ÷ 3 hours = 40 mph.
What is a knot and why is it used?
A knot is one nautical mile per hour (approximately 1.15078 mph or 1.852 km/h). It is used in aviation and maritime navigation because the nautical mile is based on the Earth's circumference, making it convenient for chart work and navigation. One nautical mile equals one minute of latitude.
How fast is the speed of sound?
The speed of sound in dry air at 20°C (68°F) at sea level is approximately 343 m/s (1,235 km/h or 767 mph). This is known as Mach 1. The speed varies with temperature and altitude.
How do I convert pace to speed?
To convert pace (min/km) to speed (km/h), divide 60 by the pace in minutes. For a pace of 5:00 min/km, speed = 60 ÷ 5 = 12 km/h. For pace in min/mile, speed = 60 ÷ pace × 1.60934 km/h.
What is the fastest speed ever recorded?
The fastest land speed record is 763.035 mph (1,227.985 km/h), set by the ThrustSSC in 1997. The fastest speed in the universe is the speed of light at approximately 299,792,458 m/s (about 670,616,629 mph).