How To Convert Mph To Kph Calculator
Miles per hour to kilometres per hour is the simplest kind of rate conversion, because both rates are per hour and the hour cancels, leaving a single exact factor of 1.609344. Almost every mistake in the topic comes from rounding that factor or from changing the time unit when the question did not ask for it.
Speed in kilometres per hour
96.5606
- The same speed in metres per second
- 26.8224
- The same speed in feet per second
- 88
- Converted back to miles per hour (check)
- 60
Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.
The formula this calculator uses
kph = mph x 1.609344
- mph
- Speed in miles per hour - the road-speed unit
- 1.609344
- Exact kilometres per mile, from 1 mile = 1609.344 m
- kph
- Speed in kilometres per hour
- 3.6
- Kilometres per hour in one metre per second, used to reach m/s
How to check the result by hand
- 1
Confirm that both rates are per hour
Miles per hour and kilometres per hour share the hour, so it cancels and the conversion is a pure length ratio with the single factor 1.609344. Read the question carefully before choosing a factor, because if the target is metres per second then the time unit changes as well and a second factor is required. 60 mph to kph is one multiplication; 60 mph to m/s is two steps, and treating the first case as the second is the most common error on this page.
- 2
Multiply by the exact factor 1.609344
The factor is exact, so use every digit. For 60 mph the calculation is 60 x 1.609344 = 96.56064 kph, and for 100 mph it is 100 x 1.609344 = 160.9344 kph. Writing the units alongside the numbers, miles per hour x kilometres per mile, makes the cancellation visible and settles any doubt about whether to multiply or divide. Rounding the factor to 1.6 here is the point at which a correct method starts producing a wrong answer.
- 3
Reach metres per second by dividing the kph figure by 3.6
Because one metre per second equals exactly 3.6 kilometres per hour, 96.56064 / 3.6 = 26.822400000000002 m/s. The same result comes from multiplying the original speed by 0.44704, the metres-per-second value of one mile per hour. The 3.6 is exact, not a rounded constant, so no precision is lost in this step. If a physics problem wants SI units, this is the line that supplies them.
- 4
Compute feet per second if the imperial unit is wanted
A mile is 5280 feet and an hour is 3600 seconds, so 60 x 5280 / 3600 = 88.0 feet per second. This is the cleanest of the three outputs and a good anchor for sanity checks: 88 feet per second for 60 mph, and therefore about 1.4666667 feet per second for every mile per hour. If the kph and the m/s figures agree but the ft/s figure looks wrong, a digit has usually been dropped in the division.
- 5
Round-trip the answer, then round once at the end
Divide the kilometres-per-hour result by 1.609344 and confirm you land on the speed you started with: 96.56064 / 1.609344 = 60. The check costs one line and catches the two errors that matter, applying the factor in the wrong direction and applying it twice. Because the factor is exact, the round trip closes exactly rather than merely coming close. Round only when you write the result down, and to a precision the original reading can support.
For worked examples, common mistakes and the limits of this formula, read the full How To Convert Mph To Kph page.