Speed Calculator

Calculate speed, distance, or time using the formula v = d/t. Enter any two values to find the third. Perfect for travel planning, physics problems, and racing calculations.

Speed

50.00 mph

Distance

150.00 mi

Time

3.0000 hours

Speed, Distance, and Time Relationship

The relationship between speed, distance, and time is one of the most fundamental formulas in physics: distance = speed × time. This formula works for any type of motion with constant speed. For varying speeds, the formula gives average speed over the entire journey.

Typical Speeds Reference

Activitymphkm/hm/s
Walking pace3-45-6.51.3-1.8
Running (jog)5-68-102.2-2.7
Running (sprint)10-1516-244.5-6.7
Cycling12-1820-305.5-8.3
Car (city)25-3540-5611-16
Car (highway)55-7589-12125-34
Commercial jet550885246
Speed of sound7671,235343

Frequently Asked Questions

How do I calculate average speed?
Average speed is calculated by dividing total distance by total time: v = d / t. For example, driving 150 miles in 3 hours gives an average speed of 50 mph. This differs from instantaneous speed, which is the speed at a specific moment. Average speed accounts for all stops and slowdowns during the trip.
What is the difference between speed and velocity?
Speed is a scalar quantity that only measures how fast an object is moving, while velocity is a vector that includes both speed and direction. Speed is always positive, but velocity can be negative if moving in the opposite direction. For example, a car driving at 60 mph north has a speed of 60 mph and a velocity of 60 mph north.
How do I convert between mph and km/h?
To convert miles per hour to kilometers per hour, multiply by 1.60934. To convert km/h to mph, divide by 1.60934. For quick mental math: 60 mph ≈ 100 km/h, 30 mph ≈ 50 km/h, and 100 mph ≈ 160 km/h. For more precise conversions, use our Mile to KM Converter tool.

Related Tools