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 units/h

Distance

150.00 units

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.

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