Speed Distance Time Calculator

Calculate speed, distance, or time using d = st. Enter two known values to solve for the third with unit conversion.

Use the formula d = s × t to find speed, distance, or time. Pick what to solve for, enter the known values, and calculate.

speed = distance / time

Try:
help_outlineHow to Useexpand_more

Choose what you want to calculate, enter the two known values, select your units, and click Calculate. The answer appears instantly along with the formula used.

Three modes available:

  • Solve for Speed — enter distance and time
  • Solve for Distance — enter speed and time
  • Solve for Time — enter distance and speed

Unit mixing is supported:

You can mix units freely — for example, distance in miles and time in minutes. The calculator converts everything internally and returns the result in your chosen output unit.

infoWhat is Speed Distance Time Calculator?expand_more

The Speed Distance Time Calculator uses the core physics formula d = s × t (distance = speed × time) to find any one of the three values when the other two are known. Rate and speed are interchangeable — both describe distance covered per unit of time.

Speed (s)

How fast something moves

mph, km/h, m/s…

Distance (d)

How far something travels

miles, km, meters…

Time (t)

How long the journey takes

hours, minutes, seconds…

The formula also applies to rate problems: if rate r equals speed s, then d = r × t gives the same result.

functionsFormulaexpand_more

Core formula:

d = s × t  (distance = speed × time)

Rearranged for each unknown:

Speed:  s = d / t

Distance:  d = s × t

Time:  t = d / s

Worked example — Find speed:

A car travels 120 miles in 2 hours.

Step 1: Use s = d / t

s = 120 mi / 2 hr

Result: s = 60 mph

Worked example — Find time:

A train moves at 100 km/h and must cover 350 km.

Step 1: Use t = d / s

t = 350 km / 100 km/h

Result: t = 3.5 hours

lightbulbExamplesexpand_more

Find speed

120 mi / 2 hr = 60 mph

s = d / t

Find distance

55 mph × 3 hr = 165 miles

d = s × t

Find time

300 km / 100 km/h = 3 hr

t = d / s

Mixed units

10 mi / 30 min = 20 mph

auto unit conversion

Metric speed

500 m / 20 s = 25 m/s

s = d / t

Knots

60 nmi / 3 hr = 20 knots

nautical miles per hour

quizFAQexpand_more
What does d = st mean?expand_more
It means distance equals speed multiplied by time. For example, driving at 50 mph for 2 hours covers 100 miles. Rearranged: s = d/t and t = d/s.
What is the difference between speed and velocity?expand_more
Speed is a scalar — it only measures how fast. Velocity is a vector — it includes direction. For this calculator, speed and rate are interchangeable.
Can I use different units for distance and speed?expand_more
Yes. The calculator converts all inputs to a common base unit internally before solving. You can enter distance in miles and time in minutes and still get the correct speed in km/h.
How do I find average speed for a round trip?expand_more
Average speed = total distance / total time. If you travel 60 miles out at 60 mph (1 hr) and 60 miles back at 30 mph (2 hr), the average speed is 120 miles / 3 hours = 40 mph — not the arithmetic average of 60 and 30.
What units of speed does this calculator support?expand_more
mph, km/h, m/s, ft/s, knots, mi/min, km/min, m/min, and several more. Select the desired unit from the speed dropdown after choosing what to solve for.
How do I convert km/h to mph?expand_more
1 km/h ≈ 0.6214 mph. You can use this calculator: enter 1 km as distance and 1 hour as time to solve for speed, then change the speed unit to mph. Or just multiply km/h by 0.6214.