Home & Garden calculator

Free speed / distance / time calculator

Solve the speed–distance–time triangle instantly — enter any two values and find the third, with consistent unit guidance for mph, km/h, minutes, and hours.

On this page10 sections

InputsLive

Speed unit

Distance

Time

Speed

Enter any two values; the third is calculated.

Result

Speed

60 mph

d ÷ t = 240 ÷ 4 hr

Distance240

Time4 hr

Speed60 mph

Formulad = s × t

Assumes constant speed (no acceleration or deceleration). Enter all values in the same unit system for accurate results — e.g. miles and hours for mph, km and hours for km/h, metres and seconds for m/s.

Results are estimates. Consult a professional.

How it's calculated

How the speed, distance, and time calculator works

Speed, distance, and time are linked by a single triangle: distance equals speed multiplied by time. Give any two of the three and the calculator solves for the third instantly. Choose what you want to find, enter the other two values, pick matching units, and the answer appears as you type.

distance = speed × time

speed = distance ÷ time

time = distance ÷ speed

The speed–distance–time relationship is a foundational kinematic equation. The consistent-units requirement follows directly from dimensional analysis as described in NIST Guide to the SI, Appendix B (unit coherence).

Example

Worked examples: all three solve modes

Example A — find speed: 240 miles in 4 hours

Aisha drives 240 miles from London to Leeds in 4 hours. What was her average speed? Speed = distance ÷ time = 240 ÷ 4 = 60 mph.

Example B — find distance: 85 km/h for 2.5 hours

A train travels at 85 km/h for 2.5 hours. How far does it go? Distance = speed × time = 85 × 2.5 = 212.5 km.

Example C — find time: 330 miles at 55 mph

A delivery van must cover 330 miles at an average of 55 mph. How long will it take? Time = distance ÷ speed = 330 ÷ 55 = 6 hours.

60 mph · 212.5 km · 6 h

All three solve modes use the same triangle. The calculator picks the correct rearrangement based on which field you leave blank.

Quick reference

Speed, distance, and time for common journeys

This table shows typical travel scenarios across road, rail, and running. Values assume a constant average speed for the full trip — real journeys include stops and acceleration, so treat these as planning estimates.

Mode / scenario	Speed	Distance	Time
City commute (car)	30 mph	15 miles	0.5 h (30 min)
Highway drive	65 mph	325 miles	5 h
Intercity train	100 mph	300 miles	3 h
Cycling (leisure)	12 mph	24 miles	2 h
5 K run (avg pace)	6.2 mph	3.1 miles	0.5 h (30 min)
Brisk walk	3.5 mph	7 miles	2 h
Motorway (km/h)	110 km/h	440 km	4 h

All figures use d = s × t with consistent units. Times rounded to the nearest minute for the running and walking rows.

Practical tips

When to use it and common unit pitfalls

The calculator covers any motion where average speed is roughly constant over the period: road trips, running paces, cycling segments, flight legs, or rough estimates for boats and trains. It does not model acceleration, variable speed, or traffic stops — add a buffer for those.

Road trips — enter the miles or kilometres and your target average speed (typically 55–65 mph on highways) to get a realistic drive time before stops.
Running pace — convert pace (min/mile) to speed first: divide 60 by your min/mile pace to get mph, then use the calculator normally.
Flight planning — use true airspeed and great-circle distance for rough leg times; add taxi and ATC delays separately.
Unit mixing — the main gotcha — if your speed is in km/h, time must be in hours; if you have minutes, divide by 60 before entering. Forgetting this is the most common source of wrong answers.

Convert time to decimal hours first

1 hour 30 minutes is 1.5 h, not 1.30. Entering 1.30 in a decimal hour field overstates the time by 30 minutes and undercounts the distance by ~25 miles at highway speed.

Accuracy & limits

Accuracy and limitations

The arithmetic is exact — the calculator does not round intermediate steps. If your inputs are precise, the result is precise to as many significant figures as you enter. The limitation is not the math; it is the assumption of constant average speed.

Real motion is rarely at a steady pace. A 200-mile road trip at 60 mph takes exactly 3 h 20 min in arithmetic, but adds 10–30 minutes once you factor in city traffic at each end, fuel stops, and construction delays. Use the calculator for planning and sanity-checking, then build in a real-world buffer. For acceleration-heavy scenarios — sprints, vehicle performance tests — you need a kinematic calculator that handles changing velocity, not a constant-speed triangle.

Definitions

Speed, distance, and time definitions

The rate at which distance is covered per unit of time. Common units: miles per hour (mph), kilometres per hour (km/h), metres per second (m/s). In this formula, speed is the average over the whole trip — not the instantaneous speedometer reading.

The total length of the path travelled, measured in miles, kilometres, metres, or any consistent length unit. It is a scalar (magnitude only), not a vector — a round trip of 100 km total is 100 km of distance regardless of direction.

The duration of travel, measured in hours, minutes, or seconds. For the formula to work, the time unit must match the denominator of the speed unit: mph requires hours; m/s requires seconds.

Total distance divided by total elapsed time. It smooths over stops, acceleration, and variable pace into a single number — the constant speed that would cover the same distance in the same elapsed time.

The requirement that the units on both sides of an equation balance. Speed (miles/hour) × time (hours) = miles; the hours cancel, leaving distance in miles. Mixing km/h with minutes — without converting — violates this and gives a wrong answer.

Speed is magnitude only; velocity adds direction. The formula d = s × t works for speed (scalar). For problems involving direction, displacement, or vectors, you need kinematics beyond this triangle.

About

About this speed, distance, and time calculator

This calculator runs entirely in your browser. No data is sent to any server, no account is needed, and nothing is stored — close the tab and the inputs are gone. It works on any device and is free to use.

Browse more home & garden calculators or explore the full library of free calculators covering finance, health, math, and everyday tasks.

Questions

Frequently asked questions about the free speed / distance / time calculator

A speed calculator is a free online tool that helps you solve distance = speed × time — calculate any of the three given the other two. The fundamental motion equation. Units must match consistently — mi+h → mph, km+h → km/h. It runs entirely in your browser with instant results and no sign-up.

This calculator gives the average speed. For varying speed, you'd need calculus (∫v dt) or to break the trip into constant-speed segments and sum the distances.

Anything consistent. mph + hours → miles. km/h + hours → km. m/s + seconds → meters. The calculator doesn't care which — just keep them aligned.

Speed is scalar (just magnitude). Velocity is a vector (magnitude + direction). For straight-line motion the numbers match; for navigation / projectile problems, direction matters.