Example 1
A constant 33.33 m/s for 5,400 s, which is 1.5 h. The missing quantity is distance.
s = 179,982.00 m
Uniform Motion Calculator
Enter exactly two of the three quantities: speed v, distance s, and time t. The calculator finds the missing one from s = v·t at constant v. At 33.33 m/s for 5,400 s the distance is 179,982.00 m. The model does not include acceleration or stops.
Result
Enter exactly two of the three quantities. The missing quantity, the other two, and the distance chart will appear here.
Distance alone, in km/h and hours, is on the distance calculator. A trip that includes stops belongs on the average speed calculator. Speeding up belongs on the uniformly accelerated motion calculator.
How it works
v33.33 m/s
t5,400 s
s179,982 m
Uniform rectilinear motion is motion in which the speed does not change with time. The calculator finds the missing one of three quantities from s = v·t, v = s/t, and t = s/v. For v = 33.33 m/s and t = 5,400 s the product is 33.33 × 5,400 = 179,982 m. The panel shows a distance of 179,982.00 m, a speed of 33.33 m/s (120.0 km/h), and a time of 5,400.00 s (90.00 min).
The calculator uses the numbers you enter: speed v in m/s, distance s in meters, and time t in seconds. A blank field is the unknown and does not mean zero. Enter exactly two quantities. At 6.00 m/s over 36,000 m the time is 6,000.00 s (100.00 min). At 8.00 m/s over 480 m the time is 60.00 s (1.00 min). For 240,000 m in 4,320 s the speed is 55.56 m/s (200.0 km/h).
What the result panel shows. Besides the missing quantity, the calculator reports speed, distance, and time after it solves, rounded the same way as the main result. Speed is given in m/s and in km/h. A time of 60 s or more also shows minutes. The chart draws distance against time: at constant v that graph is a straight line. A comma and a period in a field mean the same number.
Limits of the model. The formula assumes one constant speed along a straight line. It does not include stops, drag, or gear changes. The average speed calculator divides the whole distance by the whole time, stops included. The distance calculator finds only s = v·t, with speed in km/h and time in hours. Uniformly accelerated motion adds the term ½·a·t². The acceleration calculator finds a = Δv/t. Kinetic energy is on another page, because this calculator has no mass field. A time of zero, a negative time, a negative distance, and a negative speed produce no result.
The unit switch in the header converts displayed meters to feet and m/s to ft/s, but the formula stays the same. The numbers in this text are SI reference values. With the header set to US units, 33.33 m/s is shown as 109.35 ft/s (74.6 mph). The number 120 in a field labeled m/s means 432.0 km/h, not 120 km/h, and not 120 mph. One hundred twenty kilometers per hour is entered as 33.33. The product 33.33 × 3.6 is 119.988 km/h, and the panel rounds that speed to 120.0 km/h. A time of 0 does not pass. A blank time field is not zero.
Further examples on this page: 4.00 m/s for 750 s gives 3,000.00 m. 9,000 m in 2,700 s gives 3.33 m/s (12.0 km/h). 22,000 m at 12.00 m/s gives 1,833.33 s (30.56 min). 250.00 m/s for 2,400 s gives 600,000.00 m. The button “Fill this example” enters those same numbers into the fields and refreshes the panel and the chart.
Formula
s = v · t
v = s / t and t = s / v
Model: uniform rectilinear motion (constant speed; Galileo’s definition in the Discorsi, 1638). The calculator reads exactly two fields and finds the third. It does not solve motion with acceleration.
Check: 33.33 m/s × 5,400 s = 179,982 m. The panel shows 179,982.00 m.
Theory, derivation, and domain
Definition of uniform motion
Uniform rectilinear motion is motion in which speed is constant in magnitude and direction. Every second adds the same number of meters. Instantaneous speed is v(t) = v, and the distance from time zero is s(t) = v·t. The SI unit of speed is the meter per second. In a school course the word “uniform” means the acceleration is zero. This calculator does not read an acceleration and does not add a term with the square of time.
The model describes a stretch at one steady speedometer reading, a conveyor in a textbook problem, and sound at one speed, provided v really does not change. It does not describe traffic lights, a jam, gear changes, or wind. Mass is not in the formula: at a given speed the distance does not depend on mass.
History: equal distances in equal times
In Discorsi e dimostrazioni matematiche intorno a due nuove scienze (1638), on the third day, Galileo Galilei defined uniform motion as motion in which the moving body covers equal distances in any equal intervals of time. That is a definition of constant speed, not a separate discovery of a “miles formula.” The inclined-plane experiments and distance growing with the square of time belong to accelerated motion, and they live on another page.
The same relation is standard kinematics: OpenStax, College Physics 2e, section 2.3 “Time, Velocity, and Speed”; D. Halliday, R. Resnick, and J. Walker, Fundamentals of Physics, the chapter on motion in a straight line. When speed is constant, average speed equals instantaneous speed, so the quotient s/t is that same v.
Derivation of the formulas this calculator uses
Step 1. Constant v means the distance gained in time t is the product v·t, so s = v·t. Step 2. When s and t are known and t is greater than zero, v = s/t. Step 3. When s and v are known and v is greater than zero, t = s/v. Step 4. Distance check: 33.33 × 5,400 = 179,982, and the panel shows 179,982.00 m, with speed 33.33 m/s (120.0 km/h) and time 5,400.00 s (90.00 min). Step 5. Speed check: 240,000 / 4,320 = 55.555… The panel shows 55.56 m/s (200.0 km/h). Step 6. Time check: 480 / 8 = 60, and the panel shows 60.00 s (1.00 min).
The calculator always leaves exactly one field blank. Three numbers at once do not say which quantity to solve for. One number does not determine two unknowns. A blank field is not zero: rest requires 0 to be entered.
What this calculator does not find
The calculator does not find acceleration, force, or energy. If you know two speeds and a time, open the acceleration calculator: a = Δv/t. When speed increases at a constant acceleration, open the uniformly accelerated motion calculator. When the only question is distance, and the speed is in km/h with the time in hours, open the distance calculator. When the trip includes stops, open average speed. Kinetic energy, ½mv², is on its own page.
The result is the length of the path at the entered speed, not a signed vector. A negative speed and a negative distance are rejected. A time of 0 and a negative time produce no result, because division by a zero time is not defined here, and a product at t = 0 does not stand in for a blank field.
Orders of magnitude
33.33 m/s for 5,400 s gives 179,982.00 m, which is 179.982 km. That is the order of a highway problem for an hour and a half, not a reading off one speedometer. 6.00 m/s over 36,000 m gives 6,000.00 s, or 100.00 min. 8.00 m/s over 480 m gives one minute. 250.00 m/s for 2,400 s gives 600,000.00 m: that is the order of the speed of sound in a textbook problem, not a claim about one aircraft.
Sources
The definition and the derivation come from mechanics textbooks: OpenStax, College Physics 2e, section 2.3; D. Halliday, R. Resnick, and J. Walker, Fundamentals of Physics; H. D. Young and R. A. Freedman, University Physics, “Motion Along a Straight Line”; Galileo Galilei, Discorsi, 1638; BIPM, The International System of Units (SI), 9th edition (meter, second). This page is educational.
How to use
- Decide which quantity you want: v, s, or t. Leave that field blank. The calculator finds that one quantity.
- Enter the other two. A distance example is v = 33.33 and t = 5400. Enter 120 km/h as 33.33, not as 120 in the m/s field.
- Choose Calculate, or wait for the live result. When you enter 33.33 and 5400, the calculator shows 179,982.00 m.
- Do not enter three numbers at once. One number is not enough. A time of zero, a negative time, a negative speed, and a negative distance produce no result.
- Clear removes the inputs and hides the panel. Distance alone in kilometers per hour is on the distance calculator.
Symbol glossary
The calculator reads exactly two of the three fields and finds the third. For v = 33.33 m/s and t = 5,400 s the result is 179,982.00 m.
- v
- Constant speed [m/s]. An entered 0 is rest. A blank field is the unknown, not zero.
- s
- Distance [m], s = v·t. At constant v it grows in proportion to time.
- t
- Time [s], greater than zero when it is entered. From 60 s upward the panel also shows minutes.
- ?
- The missing quantity: the one of the three that was not entered. Enter numbers in exactly two fields.
Worked examples
Example 2
A stretch of 240,000 m covered in 4,320 s, which is 72.00 min. The missing quantity is speed.
v = 55.56 m/s (200.0 km/h)
Example 3
A stretch of 36,000 m at a constant 6.00 m/s. The missing quantity is time.
t = 6,000.00 s (100.00 min)
Example 4
A constant 8.00 m/s over 480 m. The missing quantity is time.
t = 60.00 s (1.00 min)
Example 5
A stretch of 9,000 m covered in 2,700 s, which is 45.00 min. The missing quantity is speed.
v = 3.33 m/s (12.0 km/h)
Example 6
A constant 4.00 m/s for 750 s, which is 12.50 min. The missing quantity is distance.
s = 3,000.00 m
Example 7
A stretch of 22,000 m at a constant 12.00 m/s. The missing quantity is time.
t = 1,833.33 s (30.56 min)
Example 8
A constant 250.00 m/s for 2,400 s, which is 40.00 min. The missing quantity is distance.
s = 600,000.00 m
Ways to use it
- Find the distance at a constant 33.33 m/s for 5,400 s and compare it with 179,982.00 m.
- Check the time for 480 m at a constant 8.00 m/s: the result is 60.00 s.
- Read a constant speed from a distance and a time, with no stops and no acceleration.
Common questions
What does this calculator find, and from which formula?
The calculator finds the missing one of three quantities in uniform rectilinear motion: s = v·t, v = s/t, or t = s/v. Speed stays constant for the whole time. For 33.33 m/s and 5,400 s the distance is 179,982.00 m, and the panel describes that speed as 33.33 m/s (120.0 km/h) and that time as 5,400.00 s (90.00 min). The calculator does not find acceleration.
Which units should I enter for speed, distance, and time?
Enter speed in meters per second, distance in meters, and time in seconds. Enter 120 km/h as 33.33, because the panel then shows 120.0 km/h. One hour is 3,600 s, and 1.5 h is 5,400 s. The unit switch in the header converts the result to feet and ft/s, but seconds stay seconds. The number 120 in a field labeled m/s means 120 m/s, which is 432.0 km/h, not 120 km/h and not 120 mph.
How many fields do I fill, and how is a blank different from zero?
The calculator requires exactly two numbers. The third field stays blank and is the unknown. A blank field does not mean zero. Three numbers at once, or only one, produce no result and a message appears. An entered 0 for speed, with a positive time and a blank distance, gives a distance of 0.00 m. An entered 0 for speed with a known positive distance does not give a time.
How is this result different from the distance-only calculator?
The distance calculator always finds s = v·t. It reads speed in kilometers per hour and time in hours, and the panel also shows pace. Here the unknown can be distance, speed, or time, and the fields are in meters per second, meters, and seconds. This calculator does not report pace.
How is uniform motion different from accelerated motion?
Here the acceleration is zero, and the speed at the end of the interval equals the speed at the start. The uniformly accelerated motion calculator reads initial speed, acceleration, and time, and it finds distance from s = v₀·t + ½·a·t². One constant speed does not replace those three fields.
Where do I find speed when the trip includes stops?
On the average speed page. This formula assumes one constant speed for the whole time you enter. A stop lowers the average and is not inside s = v·t, unless the number in the speed field is already the average for the whole trip and the time includes the stops.
Why does 120 in the speed field not mean 120 km/h?
The field label is meters per second. 120 in that field is 120 m/s, which is 432.0 km/h. One hundred twenty kilometers per hour is entered as 33.33. A comma and a period mean the same number, for example 33,33 and 33.33.
How do I convert meters per second to miles per hour?
Multiply m/s by about 2.237. 33.33 m/s is about 74.6 mph, and in US units the panel shows 109.35 ft/s (74.6 mph). Multiply m/s by 3.6 for kilometers per hour: 33.33 × 3.6 is 119.988, which the metric panel rounds to 120.0 km/h. The other way, 60 mph is about 26.8 m/s.
What happens when speed or distance is zero?
A speed of 0 with a positive time and a blank distance gives a distance of 0.00 m, because the body is at rest. A distance of 0 with a positive time gives a speed of 0.00 m/s. Time at a speed of 0 and a positive distance is not finite, so the calculator shows a message and does not report a result. A time entered as 0 or as a negative number also produces no result. A negative distance and a negative speed are rejected.
What does the chart under the result show?
Distance against time at the solved constant speed, at the instants 0.25 t, 0.5 t, t, 1.5 t, 2 t, and 3 t. At constant speed the chart is a straight line through the origin, and the slope matches the speed. The chart refreshes with the panel, including after an example is filled. When the speed is zero, the line is not drawn.
How do I calculate distance with s = v·t?
Multiply speed in m/s by time in seconds. For 33.33 m/s and 5,400 s: 33.33·5,400 = 179,982 m.
How do I find time when distance and speed are known?
Divide distance by speed: t = s/v. At 36,000 m and 6 m/s the result is 6,000 s, or 100 min.
How do I convert 120 km/h into the speed field in m/s?
Divide by 3.6. 120 km/h is 33.33 m/s. Enter 33.33 in the field, not 120.
How is this page different from the distance-only calculator?
Here you can leave any one of v, s, or t blank. The distance companion only computes s = v·t with speed in km/h and time in hours.
How is uniform motion different from average speed with stops?
Here v is constant on the whole segment. When the trip includes stops, use the average-speed calculator with total distance and total time.
Sources
The definition, history, and derivation below come from standard physics and metrology sources.
- OpenStax, College Physics 2e — 2.3 Time, Velocity, and Speed
- OpenStax, University Physics Volume 1 — Position, Displacement, and Average Velocity
- Wikipedia — Speed
- Wikipedia — Velocity
- Feynman Lectures on Physics, Vol. I, Ch. 8 — Motion
- BIPM — The International System of Units (SI), 9th edition
- NIST — SI units
- Galilei, G., Discorsi e dimostrazioni matematiche intorno a due nuove scienze, 1638, third day (definition of uniform motion).
- Halliday, D.; Resnick, R.; Walker, J., Fundamentals of Physics — motion in a straight line.
- Young, H. D.; Freedman, R. A., University Physics — Motion Along a Straight Line.
Page updated November 3, 2026.