55 miles per hour to kilometers per hour
88.5 km/h
55 mph = 88.5 km/h.
kilometers per hour
88.5km/h
55 mph = 88.5 km/h
In short
How many kilometers per hour is 55 miles per hour?
55 mph = 88.5 km/h. 1 miles per hour = 1.609344 kilometers per hour, so the working is 55 × 1.609344 = 88.5.
The working
The factor below is an exact definition rather than a measurement, so nothing is approximated in the arithmetic. The only rounding on this page happens where a number is displayed.
1 miles per hour = 1.609344 kilometers per hour 55 × 1.609344 = 88.5
How much precision do you need?
Each row is the same answer cut at a different number of decimals, with what that choice costs you. Pick the shortest row whose error is smaller than whatever you are measuring with.
| Rounded to | Answer (km/h) | Off by |
|---|---|---|
| Whole number | 89 | +0.48608 |
| 1 decimal | 88.5 | −0.01392 |
| 2 decimals | 88.51 | −0.00392 |
Round trip: take 88.5 km/h back the other way and you land on 54.9914 mph — a drift of 0.0086 mph. That gap is the rounding, not the conversion.
What 55 mph looks like
56 mph
Congress imposed a nationwide 55 mph maximum on American highways in 1974 to save fuel; the requirement was repealed in 1995.
Frequently asked questions
What is 55 miles per hour in kilometers per hour?
55 miles per hour is 88.5 kilometers per hour. 1 miles per hour = 1.609344 kilometers per hour, so the working is 55 × 1.609344 = 88.5.
How accurate is 88.5 km/h?
Rounding to 88.5 km/h and converting straight back gives 54.9914 mph, a drift of 0.0086 mph from the 55 you started with. The factor itself is exact; every bit of that difference comes from the rounding, not the conversion.
Nearby values
Any value at all
MPH to KM/H Converter
Miles per hour to kilometers per hour, with the speed limits you will actually meet.
Open the MPH to KM/H converter →