km/h to mph formula
To convert kilometers per hour to miles per hour, multiply the number of kilometers per hour by 0.621371192237. In symbols: mph = km/h × 0.621371192237.
One kilometer per hour equals 0.621371192237 miles per hour, and one mile per hour equals 1.609344 kilometers per hour. Since a mile is exactly 1.609344 km, 1 km/h is exactly 0.6213711922 mph.
Worked example
Suppose you have 100 kilometers per hour and need the answer in miles per hour.
- Write the formula: mph = km/h × 0.621371192237.
- Put in the number: 100 × 0.621371192237 = 62.13711922.
- Round to suit the job. 62.14 mph is accurate enough for most everyday uses.
So 100 km/h is 62.13711922 mph. To check, convert back: 62.13711922 mph is 100 km/h.
Common kilometers per hour to miles per hour values
| kilometers per hour (km/h) | miles per hour (mph) |
|---|---|
| 1 | 0.6213711922 |
| 2 | 1.242742384 |
| 5 | 3.106855961 |
| 10 | 6.213711922 |
| 20 | 12.42742384 |
| 50 | 31.06855961 |
| 100 | 62.13711922 |
Reference points
Some familiar amounts in kilometers per hour, converted to miles per hour:
- 30 km/h, an urban limit: 18.6411 mph
- 50 km/h, a typical town limit: 31.0686 mph
- 100 km/h, a rural highway: 62.1371 mph
- 130 km/h, a motorway limit: 80.7783 mph
Where you will use it
European and Asian road limits, cycling speeds and train timetables use km/h, but US and UK drivers read mph. Comparing a car top speed or a wind forecast needs this direction.
Quick mental math
Multiply by 0.6 and add 3 percent. 100 km/h is 60 plus 1.8, about 62 mph. Rule of thumb: multiply by 0.62. For 100 km/h this gives 62 mph against the exact 62.14, an error of 0.22 percent.
Going the other way
Need the reverse? Use the mph to km/h converter. For comparison, 1 mph is 1.609344 km/h. To compare every speed unit at once, open the speed converter.
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