Convert miles per hour to kilometers per hour — and back — with the exact factor (1 mph = 1.609344 km/h). Loads with mph → km/h preselected: for reading US roads, storm reports, and sports radar guns in metric. (Driving where limits are posted in km/h? The km/h to mph converter starts reversed, with the European speed-limit cheat sheet.)
The formula
km/h = mph × 1.609344 · mph = km/h × 0.62137119. Mental math: add 60% — 70 mph → 70 + 42 = 112 km/h (true 112.65).
US road speeds
| mph | km/h | Where |
|---|---|---|
| 25 | 40.2 | Residential streets |
| 35 | 56.3 | City arterials |
| 55 | 88.5 | Older highways |
| 65 | 104.6 | Typical interstate |
| 70 | 112.7 | Interstate (most) |
| 75 | 120.7 | Western interstates |
| 80 | 128.7 | TX/UT stretches |
Rentals, storms, radar guns
Driving in the US with a metric-trained brain: the table is the recalibration — and US speedometers show km/h only on the small inner ring, so memorize 25/55/70. Weather: hurricane categories are mph-defined (FAQ), so international coverage of the same storm quotes different-looking numbers. Sports: fastballs, serves, and F1 straights cross units constantly — anchors in the FAQ. Distance for the same trip converts at miles to km; nautical wind speeds in knots live in the unit converter’s Speed category.
Private by design
Runs on your device as you type — nothing transmitted. Pair with Fahrenheit to Celsius for the full US-travel kit.