Speed, Distance & Time Calculator
Calculate speed, distance or time from the other two values. Supports km/h, m/s and mph. Ideal for sports, travel and physics.
Fill in two fields and the third will be calculated automatically.
Formulas
- v = d ÷ t
- d = v × t
- t = d ÷ v
Speed, distance and time: kinematics basics
For uniform motion (constant speed), v = d / t, with the derived forms d = v · t and t = d / v. In SI units, speed is in metres per second (m/s), distance in metres and time in seconds. To convert m/s to km/h, multiply by 3.6 (since 1 m/s = 3600/1000 km/h). Example: a car covering 200 km in 2 h has v = 100 km/h ≈ 27.78 m/s. Reference speeds: a pedestrian walks at ~5 km/h, a cyclist 15–25 km/h, an urban car 50–60 km/h, a highway car 110 km/h, sound in air 343 m/s (~1,235 km/h) and light in vacuum 299,792,458 m/s — an exact value since the 1983 redefinition of the metre. Note the difference between average speed (total distance ÷ total time) and instantaneous speed (the derivative dx/dt). For accelerated motion (MRUV), use v = v₀ + at and d = v₀t + ½at².
Applications
Estimated arrival times in maps apps, traffic radar enforcement (in Brazil regulated by Lei 9.503/1997, the CTB), travel planning, sports performance (pace and split times), physics problems in school and exams like the ENEM, and basic engineering for delivery logistics.
FAQ
How do I convert km/h to m/s? Divide by 3.6. Example: 90 km/h ÷ 3.6 = 25 m/s.
Is this the same as average speed? Yes — v = d/t gives the average speed over the interval. Instantaneous speed requires calculus (derivative of position).
Does the formula work with acceleration? No. For constant acceleration (MRUV) use v = v₀ + at; v = d/t still holds for the average speed but not for instantaneous values.
Why is the speed of light exact? Since 1983 the metre is defined as the distance light travels in 1/299,792,458 of a second, fixing c by definition.
Speed, distance and time
Speed, distance and time form a trio where, knowing two, the third always falls out. This calculator applies that relationship for you. Enter two of the values and it returns the missing one, with no need to recall which formula to rearrange.
It works with the most common units, km/h, m/s and mph, which opens the door to plenty of uses: estimating how long a trip lasts, checking a run's pace, solving a physics exercise or figuring out a route's average. Swap the units as the situation asks.
The result comes out in the same moment and runs in the browser. Change any field and it recomputes on its own, which makes it easy to test different routes and paces in a few seconds.
Frequently asked questions
I filled in all three fields and the result vanished. Why?
How do I enter a time of one hour and thirty minutes?
Does it show running pace in minutes per kilometre?
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.