30 miles per hour to kilometers per hour
48.3 km/h
30 mph = 48.3 km/h.
kilometers per hour
48.3km/h
30 mph = 48.3 km/h
The short answer
How many kilometers per hour is 30 miles per hour?
30 mph = 48.3 km/h. 1 miles per hour = 1.609344 kilometers per hour, so the working is 30 × 1.609344 = 48.3.
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 30 × 1.609344 = 48.3
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 | 48 | −0.28032 |
| 1 decimal | 48.3 | +0.01968 |
| 2 decimals | 48.28 | −0.00032 |
Round trip: take 48.3 km/h back the other way and you land on 30.0122 mph — a drift of 0.0122 mph. That gap is the rounding, not the conversion.
What 30 mph looks like
30 mph
Thirty miles per hour is the default limit on street-lit built-up roads in England, Scotland and Northern Ireland.
Frequently asked questions
What is 30 miles per hour in kilometers per hour?
30 miles per hour is 48.3 kilometers per hour. 1 miles per hour = 1.609344 kilometers per hour, so the working is 30 × 1.609344 = 48.3.
How accurate is 48.3 km/h?
Rounding to 48.3 km/h and converting straight back gives 30.0122 mph, a drift of 0.0122 mph from the 30 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 →