Car, morning commute
Morning commute by car: 18.0 km in 0.367 h, before the peak starts.
In kilometers: 49.05 km/h · 13.62 m/s
Average Speed Calculator
Enter the path length and the time in hours. The calculator divides them: v̄ = s/t. At 18 km and 0.367 h the result is 49.05 km/h, or 13.62 m/s. The result includes stops that you put in the time and is not an instantaneous speedometer reading.
Result
Enter the distance and the time in hours. Average speed, meters per second, and the chart appear here.
Distance from speed and time: s = v·t. The missing one of three at constant speed: v / s / t calculator. Article: uniform motion.
How it works
s18 km
t0.367 h
v49.05 km/h
Speed on this page is the quotient of distance and time: v̄ = s/t. Distance s is the path length you enter, and time t is in hours. For 18 km and 0.367 h the quotient is 49.05 km/h. In SI units the same speed is 13.62 m/s, because the calculator divides that quotient by 3.6. That is the textbook definition of average speed (Halliday, Resnick, and Walker; Young and Freedman; OpenStax College Physics).
The calculator uses the two numbers you enter: distance (field predkosc-srednia-a) and time in hours (field predkosc-srednia-b). The result is kilometers divided by hours. The same 18 km in 0.800 h gives 22.50 km/h, or 6.25 m/s. The distance stayed the same and the time grew, so the speed is lower.
What the result panel shows. The primary result is in km/h. With miles selected in the header, the primary result is in mph, and km/h plus meters per second stay beside it. The panel repeats the distance and the time. Time is shown to three decimal places, and speed to two. The chart keeps the distance you entered and calculates speed at 0.5 h, 1 h, 1.5 h, 2 h, and 3 h.
Limits of the model. The calculator does not compute instantaneous speed, the derivative ds/dt. It does not compute average velocity from displacement: a loop can have displacement near zero and a path length equal to the sum of the legs. It does not compute acceleration or fuel use. Distance from a known speed and time is on the s = v·t page. The missing one of three quantities at constant speed is on the v / s / t calculator.
Enter time in hours, not as 1:20. 22 minutes is 22/60 h = 0.3666… h. The example button enters 0.367 h, and then 18 km gives 49.05 km/h. 48 minutes is exactly 0.800 h. One hour and 25 minutes is 85/60 h = 1.4166… h. The highway example uses 1.420 h, so 130 km gives 91.55 km/h. A comma and a period are the same decimal separator. Zero kilometers gives 0 km/h. A time of zero has no result.
The examples cover a morning car commute, the same commute in traffic, a highway leg, a cyclist, a walk, a train, and a longer car trip. The “Fill this example” button enters those numbers and refreshes the panel and the chart. The fields start empty.
Formula
v̄ = s / t
vm/s = vkm/h / 3.6
Model: average speed, the path length divided by the elapsed time. The calculator divides the distance you enter, after converting it to kilometers, by the time in hours. It does not compute a derivative or a displacement.
Theory, derivation, and domain
Average speed
Average speed is the distance traveled divided by the time that trip took. When distance is in kilometers and time is in hours, the quotient is in km/h. For 18 km and 0.367 h the quotient is 49.046… km/h, and the panel shows 49.05 km/h. That is not the speed at one point on the route. It is one number for the whole time interval.
Textbooks often put a bar over v. This calculator evaluates that quotient. The formula v = s/t does not belong to one named scientist. It is the kinematics definition used in Halliday and in OpenStax College Physics.
Instantaneous speed
Instantaneous speed is the limit of Δs/Δt as the time interval shrinks toward zero. A speedometer shows the pace at one moment. This page does not compute that limit, and it has no field for a speedometer reading. A longer time for the same distance lowers the quotient, because stops and slower stretches sit in the denominator.
Distance and displacement
Distance is the length of the path. Displacement is the vector from the start position to the end position. A trip out and back can have displacement near zero and a distance equal to the sum of both legs. Average velocity is displacement divided by time. This calculator does not compute it. It uses the distance you enter.
The calculator does not decide whether that distance came from GPS or from an odometer. The two sources can differ by a few percent. For comparing two trips, keep one source.
SI units and km/h
The SI unit of speed is the meter per second. 1 m/s = 3.6 km/h. The calculator first divides kilometers by hours, then divides that quotient by 3.6. At 18 km and 0.367 h the panel shows 13.62 m/s. With miles selected in the header, the primary result is in mph, and meters per second stay beside it, together with km/h.
Time in the field stays in hours after you switch to miles. 22 minutes is not 22 in that field. It is a fraction of an hour.
Assumptions and limits
The model assumes one distance and one time for the whole motion. It does not split the trip into legs at different speeds. When you want the average of two parts, add the distances, add the times, and divide once. The arithmetic mean of two speeds equals that quotient only when the two times are equal.
Zero kilometers gives a speed of zero. A time of zero has no result, because division by zero is undefined. The calculator does not compute acceleration, air resistance, or fuel use. Kinetic energy needs mass and speed on a separate page.
Sources
OpenStax, College Physics 2e, the section on speed and velocity. D. Halliday, R. Resnick, and J. Walker, Fundamentals of Physics, kinematics. H. D. Young and R. A. Freedman, University Physics, motion in a straight line. BIPM, The International System of Units (SI), 9th edition: the meter and the second. NIST Special Publication 330. The page is educational.
How to use
- Enter the distance. In kilometers, 18 is the morning commute in the first example.
- Enter the time in hours. 22 minutes in that example is 0.367 h. 48 minutes is 0.800 h.
- Click Calculate, or wait for the live result. For 18 km and 0.367 h the calculator shows 49.05 km/h and 13.62 m/s.
- Check the panel: speed, meters per second, the repeated distance and time, and the chart at 0.5 h, 1 h, 1.5 h, 2 h, and 3 h.
- Looking for distance from a known speed? Open s = v·t. Here the unknown stays the quotient s/t.
Symbol glossary
v is distance divided by time. For 18 km and 0.367 h the result is 49.05 km/h, or 13.62 m/s in SI units.
- v̄
- Average speed. In kilometers the panel shows km/h to two decimal places. 18 km / 0.367 h = 49.05 km/h.
- s
- Distance, the path length, field predkosc-srednia-a. This is not displacement. 18 km stays 18 km when only the time changes.
- t
- Time in hours, field predkosc-srednia-b. The panel shows it to three decimal places. 0.367 h is the 22-minute figure used in the example.
- m/s
- The SI unit. At 18 km and 0.367 h the panel shows 13.62 m/s, because it divides the exact quotient by 3.6. The rounded 49.05 km/h is not a second input.
Real-life examples
Car, the same commute in traffic
The same car route, 18.0 km, but in 0.800 h. The distance did not change. The time includes slower traffic.
In kilometers: 22.50 km/h · 6.25 m/s
Car, highway leg
A highway leg by car: 130 km in 1.420 h, with no stop for fuel.
In kilometers: 91.55 km/h · 25.43 m/s
Cyclist
A cyclist: 42.0 km in 2.170 h, including a break halfway.
In kilometers: 19.35 km/h · 5.38 m/s
Walk
A walk: 3.20 km in 0.800 h, with stops along the way.
In kilometers: 4.00 km/h · 1.11 m/s
Train
A regional train: 86.0 km in 1.200 h, with station stops included.
In kilometers: 71.67 km/h · 19.91 m/s
Longer car trip
A longer car trip: 420 km in 5.000 h, fuel stop included.
In kilometers: 84.00 km/h · 23.33 m/s
Streetcar downtown
A streetcar through downtown: 6.50 km in 0.467 h, with stops at each station.
In kilometers: 13.92 km/h · 3.87 m/s
Common questions
What does this calculator compute, and which formula does it use?
The calculator computes average speed as distance divided by time: v = s/t. You enter the path length and the time in hours. At 18 km and 0.367 h the result is 49.05 km/h, or 13.62 m/s. The panel repeats the distance and the time, and it charts the speed of that same distance at five other times.
How is this quotient different from instantaneous speed?
Instantaneous speed describes the pace at one moment. On a speedometer that is the reading at that moment. This page does not compute the derivative ds/dt. It divides the whole distance you entered by the whole time, so lights and stops make the result lower than the speed on an empty stretch.
How is distance different from displacement?
Distance is the length of the path. Displacement is the vector from the start to the finish. A trip out and back can have displacement near zero and a distance equal to the sum of the legs. This calculator uses the distance you enter. It does not compute average velocity from displacement.
Which units should I enter for distance and time?
Always enter time in hours. 22 minutes in the example is 0.367 h, because 22/60 is rounded here to three decimal places. 48 minutes is exactly 0.800 h. The field does not accept 1:20. Enter distance in kilometers or in miles, depending on the header switch. A comma and a period are the same decimal separator.
Do stops count in the result?
Yes, when the time you enter includes the stops. A door-to-door average includes fuel and a break. When you want driving pace alone, subtract the stop from the time before you enter the number. The calculator has no separate stop field.
How do I handle a trip out and back?
Add the distances and add the times, then divide once. The mean of two speeds is a different number when the two times differ. This form has one distance and one time.
Where do km/h and m/s come from?
Kilometers divided by hours is a speed in km/h, and the panel shows it to two decimal places. Meters per second come from dividing that quotient by 3.6, also to two decimal places. At 18 km and 0.367 h the panel shows 49.05 km/h and 13.62 m/s. The miles switch turns the primary result into mph. Meters per second stay on the panel.
What does this calculator not compute?
It does not compute acceleration, fuel use, time from a known speed, or distance from s = v·t. Distance from speed and time is on a separate page. The missing one of three quantities at constant speed is on the v / s / t calculator. Here the unknown is the quotient s/t.
What happens at zero distance or zero time?
Zero kilometers and a time greater than zero give 0 km/h. A time of zero or a negative time has no result, because the denominator cannot be zero. A negative distance does not reach the panel either. Empty fields leave the result area without an error message.
What does the chart under the result show?
The chart keeps the distance you entered and shows the speed at 0.5 h, 1 h, 1.5 h, 2 h, and 3 h. The vertical axis is in km/h or in mph, following the header. The “Fill this example” button enters the example numbers and refreshes the panel and the chart. The fields start empty.
How do I calculate average speed with v = s/t?
Divide total distance by total time in hours. For 18 km and 0.367 h: 18/0.367 ≈ 49.05 km/h. For 150 km in 2 h the result is 75 km/h.
How do I convert minutes to hours before entering time?
Divide minutes by 60. 22 minutes is 0.367 h, and 48 minutes is 0.800 h. The time field does not accept a 1:20 clock form.
How do I convert the result from km/h to m/s?
Divide the km/h value by 3.6. At 49.05 km/h the panel shows 13.62 m/s, because 49.05/3.6 ≈ 13.62.
Why must I not average two segment speeds?
Average speed is total distance over total time. Two 60 km legs at 60 km/h and 120 km/h give 120 km in 1.5 h, which is 80 km/h, not 90 km/h.
How is this page different from uniform-motion distance?
Here the unknown is the quotient s/t when distance and time are known. The distance companion computes s = v·t from speed and time.
Sources
The definition and the units come from physics textbooks and from metrology, with no invented DOIs.
- OpenStax — College Physics 2e, Speed and Velocity
- Wikipedia — speed
- Wikipedia — velocity
- BIPM — The International System of Units (SI), 9th edition
- NIST SP 330 — The International System of Units
- Halliday, D.; Resnick, R.; Walker, J., Fundamentals of Physics — kinematics.
- Young, H. D.; Freedman, R. A., University Physics — motion along a straight line.
Page updated November 3, 2026.