Speed Converter

How to Use This Calculator

1. Enter the speed value.
2. Select your source speed unit.
3. Select your target speed unit.
4. The converted speed is shown instantly.

Formula

Example

Frequently Asked Questions

• How many km/h is 60 mph? ▼
  60 mph equals 96.5606 km/h. The exact conversion factor is 1 mph = 1.609344 km/h (since 1 mile = 1.609344 km exactly). So 60 × 1.609344 = 96.56 km/h. A quick mental shortcut: multiply mph by 1.6 for a close estimate (60 × 1.6 = 96 km/h — only 0.6% off). Common reference conversions: 30 mph = 48.3 km/h, 55 mph = 88.5 km/h, 70 mph = 112.7 km/h, 100 mph = 160.9 km/h. For the reverse, to convert km/h to mph, multiply by 0.621371. Highway speed limits in countries that use mph (US, UK) and those using km/h (most of Europe) reflect the same practical speeds — a 70 mph UK motorway limit equals 112.7 km/h, while a German autobahn advisory speed of 130 km/h equals 80.8 mph.
• What is a knot in km/h? ▼
  One knot equals exactly 1.852 km/h = 1.15078 mph = 0.514444 m/s. A knot is one nautical mile per hour, and 1 nautical mile = 1,852 meters (one minute of arc of latitude on Earth's surface). Knots are the standard speed unit in aviation, maritime navigation, and meteorology worldwide — regardless of whether countries otherwise use metric or imperial units. When air traffic control says an aircraft is flying at "450 knots," that is 450 × 1.852 = 833.4 km/h ≈ 518 mph. Wind speeds in weather forecasts may be given in knots: a Force 8 gale is 34–40 knots = 63–74 km/h. Do not confuse knots with km/h — a "50 knot wind" is much stronger than "50 km/h wind" (it is actually 92.6 km/h).
• How fast is the speed of sound? ▼
  The speed of sound in dry air at 20°C (68°F) at sea level is approximately 343.2 m/s = 1,235 km/h = 767.3 mph = 1,125 ft/s. This is Mach 1. The speed of sound depends on the medium and temperature: in water it is about 1,480 m/s (4.3× faster); in steel, about 5,960 m/s. In air, it increases by about 0.6 m/s for every 1°C rise in temperature. At altitude (−56°C in the stratosphere), the speed of sound drops to about 295 m/s = 1,062 km/h. When a jet aircraft exceeds Mach 1, it generates a sonic boom — a shock wave caused by pressure waves piling up in front of the aircraft. Mach 2 = 686.4 m/s at sea level; Mach 5 (hypersonic) = 1,716 m/s.
• How do I convert m/s to km/h? ▼
  To convert meters per second (m/s) to kilometers per hour (km/h), multiply by 3.6. This factor comes from unit analysis: 1 m/s × (1 km / 1000 m) × (3600 s / 1 h) = 3600/1000 = 3.6 km/h. Examples: 10 m/s = 36 km/h; 30 m/s = 108 km/h (strong gale); 100 m/s = 360 km/h. To go the other way (km/h to m/s), divide by 3.6 or multiply by 1/3.6 = 0.2778. Running at 10 km/h = 2.78 m/s; a sprinter at 10 m/s = 36 km/h; a Formula 1 car at 350 km/h = 97.2 m/s. In physics, m/s is the SI unit for velocity, so most physics problems work in m/s, while everyday traffic and weather use km/h or mph.
• What is the legal speed limit in km/h vs mph? ▼
  Speed limits vary by country but common equivalences help when traveling internationally. In the US: 25 mph residential = 40 km/h; 55 mph rural highway = 89 km/h; 65–75 mph interstate = 105–121 km/h. In the UK: 30 mph urban = 48 km/h; 60 mph rural single carriageway = 97 km/h; 70 mph motorway = 113 km/h. In Europe (km/h): 50 km/h urban = 31 mph; 90–100 km/h rural = 56–62 mph; 120–130 km/h motorway = 75–81 mph. Germany has sections of autobahn without speed limits, though the advisory speed is 130 km/h (81 mph). Australia uses km/h: 60 urban, 100–110 rural. When renting a car abroad, always verify which system the speedometer uses — most modern cars show both.

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