🚀 Speed Conversion

Convert between speed units for travel, aviation, marine, and science. Supports kilometers per hour (km/h), miles per hour (mph), knots (kn), meters per second (m/s), feet per second (ft/s), Mach number, and speed of light.

Speed and velocity conversion calculates rate of distance per unit of time. The SI base unit is meters per second (m/s). 1 m/s equals exactly 3.6 kilometers per hour (km/h) or approx. 2.23694 miles per hour (mph). 1 knot (international nautical mile per hour) equals exactly 1.852 km/h.

Metrological Standards & Base Equation

1 mph = 1.60934 km/h. 1 knot = 1.15078 mph = 1.852 km/h. Mach 1 ≈ 1,235 km/h at sea level.

Speed ratios are derived from NIST SP 811 linear and temporal SI base units. Nautical speeds follow the International Hydrographic Organization (IHO) standard of 1 knot = 1,852 meters per hour exact.

Primary References: NIST SP 811 (2008 Edition) · BIPM SI Brochure (2019) · Standards Directory

Supported Speed Units (6 Total)

Speed Unit Definitions and Scaling Factors
Unit Symbol Unit Name System Equivalent in m/s
m/s m/s Metric Reference Standard (1 m/s)
km/h km/h Metric 1 km/h = 0.277778 m/s
mph mph Imperial 1 mph = 0.44704 m/s
kn Knot Other 1 kn = 0.514444 m/s
Mach Mach Other 1 Mach = 343 m/s
c Speed of Light Scientific 1 c = 299792458 m/s

Popular Speed Conversions

km/h to mph

km/h → mph — road speed limits & travel

mph to km/h

mph → km/h — international driving

Knots to mph

kn → mph — aviation & marine

m/s to km/h

m/s → km/h — physics & sports

Mach to km/h

Mach → km/h — aerospace & aviation

Common Use Cases

  • Driving & road trips (km/h↔mph)
  • Aviation (kn↔mph)
  • Marine navigation (kn)
  • Physics calculations (m/s)
  • Sports analytics (m/s↔km/h)

Frequently Asked Questions

How do I convert km/h to mph?

Divide km/h by 1.60934 to get mph. For example, 100 km/h ÷ 1.60934 = 62.14 mph.

What is the difference between knots and mph?

One knot equals 1.15078 mph. Knots are used in aviation and marine contexts, while mph is used for road travel.