Speed Distance Time Calculator

Speed Distance Time Calculator solves the missing value from the other two in km, miles, mph or knots, then adds pace, an arrival time with stops and the time a faster speed saves.

Speed Distance Time Calculator Formulas

Speed, distance and time are tied together by one relationship written three ways. The Speed Distance Time Calculator solves whichever one is missing from the other two. The Solve For menu picks the unknown, and the button changes to Calculate Speed, Calculate Distance or Calculate Time to match. That makes it a speed time calculator when distance is the unknown and a speed distance calculator when time is.

$$S=\frac{D}{T}$$

$$D=S\times T$$

$$T=\frac{D}{S}$$

The middle line is the DST formula, distance equals speed times time. The first is the formula for speed and the third is the formula for time. Together they are the three formulas people mean when they ask for the three formulas of distance.

The tool opens on 100 km in 2 hours. Speed is 100 ÷ 2, so the main result reads 50 km/h Average Speed. So 100 km in 1 hour is 100 km/h, and 100 km in 6 hours is 16.67 km/h, which is 10.36 mph.

The Speed Distance Time Triangle panel draws the memory aid, with D on top and S and T below. Covering the letter you want leaves the working. Cover S and D sits over T, so speed is distance divided by time. Cover D and S sits beside T, so distance is speed times time.

For a speed distance time calculator with solution steps, open the Solution Steps panel. It first turns the hours, minutes and seconds into one number, then shows the formula line with the entered values, such as 100 km ÷ 2 h = 50 km/h.

Mixed Units in km, Miles, mph and Knots

Hand calculations go wrong when the units do not match. A speed in km/h needs distance in kilometers and time in hours, and 30 minutes has to become 0.5 hours first. The Speed Distance Time Calculator removes that step, because time goes in as separate hours, minutes and seconds.

Distance can be entered in km, miles, meters, feet or nautical miles. Speed can be in km/h, mph, m/s, ft/s or knots. The units can be mixed, so a distance in miles and a speed in km/h still give the right time. When solving for speed, the answer comes back in the unit that matches the distance, mph for miles and km/h for km.

The first result card of the Speed Distance Time Calculator repeats the answer in three other units. For 50 km/h it shows 31.07 mph, 13.89 m/s and 45.57 ft/s. The Results in All Units panel lists every unit at once, including 27 knots and 62.14 miles for the default trip.

The conversions are exact ones. NIST's table of conversion factors gives one mile as 1.609344 km, one nautical mile as 1.852 km and one foot as 0.3048 m. So 1 km/h is 0.6214 mph and 1 mph is 1.609 km/h. A speed of 100 mph is 160.9 km/h, and 29 km/h is 18.02 mph.

Driving Time, Stops and Arrival

For driving, the usual question is time. Set Solve For to Time and the tool works as a speed distance time calculator for driving. A 150 mile trip at 65 mph takes 2 h 18 min 28 s of moving time, which is 2.308 hours.

The Trip Details panel adds a start time and a stops entry, which open at 9:00 AM and 15 minutes. The third card adds the stops to the moving time and gives the arrival. That 150 mile trip arrives at 11:33 AM after 2 h 33 min 28 s door to door.

The same card shows Average Speed With Stops. Fifteen minutes parked pulls the 65 mph down to 58.65 mph for the whole trip. On the default 100 km run it drops from 50 km/h to 44.44 km/h.

The fourth card of the Speed Distance Time Calculator answers whether driving faster is worth it. At 75 mph the 150 miles take exactly 2 hours, a saving of 18 min 28 s. At 55 mph they take 25 min 10 s longer. The loss from slowing down is always bigger than the gain from the same step up, because time is distance divided by speed.

Solving for distance works the other way. Holding 55 mph for 3 h 30 min covers 192.5 miles, or 309.8 km. The result note reminds you to leave stops out of that time, since a parked car covers no distance.

Bike Speed, Walking and Running Pace

Riders and runners think in pace, which is time per kilometer or mile. The second card turns speed upside down to show it. As a bike speed, distance and time calculator, 40 km in 1 h 45 min returns 22.86 km/h, or 14.2 mph, and a pace of 2 min 38 s per kilometer.

The CDC's guide to measuring physical activity intensity gives two useful reference speeds. Walking at 2.5 mph or faster counts as brisk, which is 4.02 km/h. Bicycling below 10 mph on level ground is moderate, and faster than 10 mph, or 16.09 km/h, is vigorous.

By that measure walking 5 km in 1 hour is a brisk walk. It is 5 km/h, or 3.107 mph, at 12 minutes per kilometer and 19 min 19 s per mile. A 2 km walk at the same speed takes 24 minutes, and at the 2.5 mph threshold it takes just under 30 minutes.

The table, taken from the Speed Distance Time Calculator, answers the common 1 km questions. One kilometer in 10 minutes is 6 km/h, well inside the CDC's brisk walking range. One kilometer in 7 minutes is 5.326 mph, more than twice that threshold, so it takes a jog and not a walk. One kilometer in 4 minutes is 15 km/h, and 1 km a minute is 60 km/h.

How long 1 km takes depends only on speed. It is 12 minutes at 5 km/h, 1 minute at 60 km/h and 36 seconds at 100 km/h. How far 1 hour goes in kilometers is the speed itself, so an hour at 29 km/h covers 29 km.

The same sum gives range for anything that runs on a battery. An e-bike that holds 25 km/h for a 2 hour charge covers 50 km. The Battery Life Calculator finds the hours a battery lasts under a load, and that time goes into the Speed Distance Time Calculator with the speed.

How Far Is 100 km?

One hundred kilometers is 62.14 miles, or 54 nautical miles. How long it takes depends on the speed entered. The Speed Distance Time Calculator in Time mode gives the figures below, and the last column is the fourth card's saving for going 10 km/h faster.

The saving shrinks fast. Going from 50 to 60 km/h saves 20 minutes over 100 km. Going from 100 to 110 km/h saves under 6 minutes, and from 110 to 120 km/h under 5. A cyclist who covers 100 km in 6 hours averages 16.67 km/h, just over the CDC's 10 mph line for vigorous riding.

Average Speed, Velocity and Measuring Speed

The answer in Speed mode is an average. The result note calls it the steady speed that covers the distance in the time given, and real trips run faster and slower along the way. OpenStax College Physics defines average speed as the distance traveled divided by elapsed time.

Velocity is calculated differently. It is displacement, the change in position, divided by time, and it carries a direction. The textbook's example is a 30 minute drive to a store and back that puts 6 km on the odometer. The average speed is 12 km/h, but the average velocity is zero because the car ends where it started.

The simplest way to measure speed is the one the Speed Distance Time Calculator uses. Time a known distance and divide. A runner who covers a 400 m lap in 1 min 36 s has gone 4.167 m/s, which is 15 km/h. A speedometer reads the speed at one instant, so it will sit above the trip average for much of a journey.

The SI unit of speed is the meter per second, and the tool shows it in the results of every calculation. Entering meters and seconds directly keeps a physics problem in SI units from start to finish.