MPH (miles per hour) vs KPH (kilometres per hour)
Side-by-side comparison, when-to-use-each guide, and instant conversion. Reviewed for 2026.
US, UK road signs and speedometers, Liberia, Myanmar.
Most of the world. Republic of Ireland switched from mph to kph in 2005.
| Aspect | MPH (miles per hour) | KPH (kilometres per hour) |
|---|---|---|
| UK motorway limit | 70 mph | 113 kph |
| Most EU motorway limits | ≈ 80-87 mph | 130-140 kph |
| Conversion | ×1.609 → kph | ×0.621 → mph |
| Speedometer dual | Most UK cars | Most European cars |
Frequently asked
How fast is 100 mph in kph?
100 mph = 160.93 kph. Mental shortcut: multiply by 1.6 (so 100 mph ≈ 160 kph). Key speeds: 30 mph = 48 kph (urban UK limit), 70 mph = 113 kph (UK motorway limit), 100 mph = 161 kph, 120 mph = 193 kph. The UK uses mph for all road speeds; EU uses kph.
Why does the UK still use mph?
The UK kept mph despite signing up to metric trade. Replacing road signs and speedometers across the country was costed at over £750 million in 2002 — politically unattractive ever since.
Frequently asked questions
How fast is 100 mph in kph?
100 mph = 160.93 kph. Mental shortcut: multiply by 1.6 (so 100 mph ≈ 160 kph). Key speeds: 30 mph = 48 kph (urban UK limit), 70 mph = 113 kph (UK motorway limit), 100 mph = 161 kph, 120 mph = 193 kph. The UK uses mph for all road speeds; EU uses kph.
Why does the UK still use mph?
The UK kept mph despite signing up to metric trade. Replacing road signs and speedometers across the country was costed at over £750 million in 2002 — politically unattractive ever since.