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Speed, Distance & Time Calculator

Solves the uniform-motion relation speed = distance / time for whichever of the three quantities is omitted, and reports the speed in m/s, km/h and mph and the time as h:mm:ss.

When to use

You know any two of distance, elapsed time and average speed for travel at constant (average) speed and need the third.

Do not use when: Speed changes during the motion (use acceleration or free-fall), or you want a running pace per km or mile (use running-pace).

Formula

speed_m_s = distance_m / time_s; distance_m = speed_m_s × time_s; time_s = distance_m / speed_m_s; speed_km_h = 3.6 × speed_m_s; speed_mph = speed_m_s / 0.44704

Uniform (constant or average) motion in a straight line; the result is the average speed over the interval, not an instantaneous value.

Inputs

Parameter	Type	Unit	Required	Description
`distance_m`	number	m	no	Distance travelled in metres (1 km = 1000 m, 1 mile = 1609.344 m). Omit to solve for it. Range: ≥ 0
`time_s`	number	s	no	Elapsed time in seconds (1 h = 3600 s). Omit to solve for it. Range: > 0
`speed_m_s`	number	m/s	no	Average speed in metres per second (km/h ÷ 3.6, mph × 0.44704). Omit to solve for it. Range: ≥ 0

Outputs

Output	Type	Unit	Description
`solved_for`	string		Which input was computed: distance_m, time_s or speed_m_s.
`distance_m`	number	m	Distance travelled.
`distance_km`	number	km	Distance in kilometres.
`time_s`	number	s	Elapsed time.
`time_formatted`	string		Elapsed time as hours:minutes:seconds, rounded to the second.
`speed_m_s`	number	m/s	Average speed.
`speed_km_h`	number	km/h	Average speed in kilometres per hour (× 3.6).
`speed_mph`	number	mph	Average speed in miles per hour (÷ 0.44704).

Example

100 m in 9.58 s (100 m world record): {"distance_m":100,"time_s":9.58} → {"solved_for":"speed_m_s","speed_m_s":10.4384,"speed_km_h":37.5783,"speed_mph":23.3501,"distance_km":0.1}

150 km at 25 m/s: {"distance_m":150000,"speed_m_s":25} → {"solved_for":"time_s","time_s":6000,"time_formatted":"1:40:00","speed_km_h":90}

GET https://tttkmbb.com/api/v1/calculate/speed-distance-time?distance_m=100&time_s=9.58

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/speed-distance-time (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/speed-distance-time · Markdown: https://tttkmbb.com/physics/speed-distance-time.md · JSON definition: https://tttkmbb.com/physics/speed-distance-time.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="speed-distance-time"
OpenAPI operationId: solve_speed_distance_time
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

FAQ

Can I enter km and hours instead of metres and seconds?

No; convert first (1 km = 1000 m, 1 h = 3600 s, 1 km/h = 0.27778 m/s). Outputs include km, km/h and mph twins so you rarely need to convert results.

What if I give all three values?

The calculator returns an INVALID_PARAMETER error: supply exactly two, and the third is computed.

Related calculators

Acceleration Calculator — When speed changes uniformly over the interval.
Running Pace Calculator — Pace per kilometre or mile for runners.
Speed Converter — Convert a known speed between m/s, km/h, mph and knots.