Speed Calculator

Calculate speed, distance, and time instantly. Free speed calculator for physics homework, travel planning, and motion calculations. Enter any two values to find the third.

Measurement System

Calculation Type *

Distance *

Time (hours) *

Smart Tips

• Speed = Distance ÷ Time is the fundamental relationship

• To convert mph to km/h, multiply by 1.609 (or divide km/h by 1.609 for mph)

• Average speed differs from instantaneous speed - use total distance and total time

• Light travels at approximately 299,792,458 meters per second in a vacuum

• Enter any two of speed, distance, and time to calculate the third value

Speed Formulas

Type	Formula
Speed	Speed = Distance ÷ Time
Distance	Distance = Speed × Time
Time	Time = Distance ÷ Speed
Average Speed	Average Speed = Total Distance ÷ Total Time

Speed Conversion Reference

Unit	Conversion
Meters per Second (m/s)	1 m/s = 3.6 km/h = 2.237 mph
Kilometers per Hour (km/h)	1 km/h = 0.278 m/s = 0.621 mph
Miles per Hour (mph)	1 mph = 0.447 m/s = 1.609 km/h
Knots	1 knot = 0.514 m/s = 1.852 km/h
Feet per Second (ft/s)	1 ft/s = 0.305 m/s = 1.097 km/h

Key Insights

Speed Formula

Speed equals distance divided by time (v = d/t). This fundamental relationship applies to all motion calculations.

Unit Conversions

Convert between mph, km/h, m/s, and knots for different applications like driving, running, and navigation.

Average vs Instantaneous

Average speed is total distance over total time, while instantaneous speed is the speed at a specific moment.

Practical Uses

Calculate travel time, estimate arrival times, and understand motion in physics and everyday situations.

Frequently Asked Questions

Speed is a scalar quantity that measures how fast something is moving, while velocity is a vector quantity that includes both speed and direction of motion.

Average speed is calculated by dividing the total distance traveled by the total time taken. For multiple segments, add up all distances and all times separately, then divide total distance by total time.

Yes, but make sure to use consistent units throughout your calculation. The result will be in the same unit system as your inputs (e.g., if distance is in meters and time in seconds, speed will be in m/s).

Speed = Distance ÷ Time. If you know any two of these values, you can calculate the third. For example, if you travel 100 miles in 2 hours, your speed is 50 mph.

Use our speed converter or conversion factors: 1 mph = 1.609 km/h, 1 m/s = 3.6 km/h, 1 knot = 1.151 mph. Our calculator handles all conversions automatically.

Our speed calculations are based on standard velocity formulas (v = d/t), International System of Units (SI) speed standards, and physics measurement principles.

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Speed

Enter values to calculate

Note: Speed calculations are based on standard distance-over-time formulas. Actual speeds may vary due to acceleration. Always observe speed limits and drive safely.