Can I use different units for distance and time?

Distance is miles or kilometers, and speed is mph or km/h. Time is always hours. The calculator does not accept meters per second or knots.

What are the sources for speed calculations?

Speed = distance / time, with time in hours. The mile factor is the international mile, 1.609344 km (NIST Special Publication 811, https://www.nist.gov/pml/special-publication-811).

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.

Distance unit

Calculation Type *

Distance *

Time (hours) *

Smart Tips

• Speed = Distance ÷ Time is the fundamental relationship

• The unit switch converts mph and miles using 1 mile = 1.609344 km. Time stays in hours.

• 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
Miles per Hour (mph)	1 mph = 1.609344 km/h
Kilometers per Hour (km/h)	1 km/h = 1/1.609344 mph

Key Insights

Speed Formula

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

Unit Conversions

This page solves speed, distance, or time in miles and mph, or kilometers and km/h. Time is entered in hours.

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.

Distance is miles or kilometers, and speed is mph or km/h, following the switch above the form. Time is always hours. Switching converts a typed distance or speed (1 mile = 1.609344 km). The calculator does not accept meters per second or knots.

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.

The switch converts between miles per hour and kilometers per hour using 1 mile = 1.609344 km. It does not convert meters per second or knots. Average speed is total distance divided by total time, not the average of the segment speeds.

Speed = distance ÷ time, distance = speed × time, and time = distance ÷ speed, with time in hours. The mile factor is the international mile, 1.609344 km, from NIST Special Publication 811.

Responsive Ad Space

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.