MPH to KM/H Converter
Type a speed in miles per hour and read the kilometers per hour value the moment you finish. The converter multiplies by the exact factor 1.609344, and a reference table below lists the common speeds from 1 to 100. Either box is editable, so you can convert km/h back to mph just as easily.
How to convert mph to km/h
- Type the speed into the left Miles per Hour (mph) box.
- Read the answer in the right Kilometers per Hour (km/h) box as it updates live.
- Edit the right box instead to convert a km/h speed back into mph.
- Scan the reference table below for whole-number speeds from 1 to 100.
- Check the 1 mph = 1.609344 km/h line to see the exact factor in use.
Examples
US freeway speed
60 mph
96.56064 km/h
Interstate speed limit
70 mph
112.65408 km/h
Reverse: a 100 km/h limit
100 km/h
62.137119 mph
Frequently asked questions
What is the formula to convert mph to km/h?
Multiply the speed in miles per hour by 1.609344, so km/h = mph times 1.609344. For example 60 mph becomes 60 times 1.609344, which is 96.56064 km/h.
Why is 1 mph equal to 1.609344 km/h?
A mile is defined as exactly 1609.344 meters, or 1.609344 kilometers. Both speeds share the same hour, so one mile per hour is exactly 1.609344 kilometers per hour.
Is this conversion exact?
Yes. The factor 1.609344 is exact by definition, so 60 mph is exactly 96.56064 km/h with no approximation. The tool shows up to six decimal places, so the displayed answer matches the exact math.
How do common US speed limits convert to km/h?
A 30 mph urban limit is 48.28032 km/h, 55 mph is 88.51392 km/h, 65 mph is 104.60736 km/h, and a 70 mph interstate limit is 112.65408 km/h.
What are some quick mph to km/h reference points?
10 mph is 16.09344 km/h, 25 mph is 40.2336 km/h, 50 mph is 80.4672 km/h, and 100 mph is 160.9344 km/h. A handy mental shortcut is to add roughly 60 percent to the mph figure.
Can I convert km/h back to mph here?
Yes. Type into the right Kilometers per Hour box and the left box shows mph, dividing by 1.609344. For instance 100 km/h works out to 62.137119 mph.
How is this different from converting knots or m/s?
This tool is fixed to miles per hour and kilometers per hour. Knots (1.852 km/h each) and meters per second are separate units, so use a dedicated speed converter for those.
Why does the result show so many decimal places?
Because the factor is exact, the answer often ends in a long tail like 96.56064. The tool rounds the display to six decimals, which is precise enough for driving, running or engineering while staying readable.
Is my data sent anywhere?
No. The conversion runs entirely in your browser, so the speeds you enter never leave your device and nothing is uploaded to a server.
Learn more
- MPH vs km/h and the exact 1.609344 factor
Why miles and kilometers give different speed numbers, where each unit is used, and how the exact 1.609344 factor is defined.
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