What is a Speed Converter?
A speed converter transforms velocity measurements from one unit to another. Speed (or velocity) measures how fast an object moves, expressed as distance traveled per unit of time. Different industries and regions use different speed units based on historical conventions and practical needs.
This converter supports common speed units used in road travel (km/h, mph), physics (m/s), maritime/aviation (knots), and aerospace (Mach number).
How Does Speed Conversion Work?
Speed conversion involves dividing or multiplying by fixed ratios:
- Convert to base unit: The input value is converted to meters per second (the SI unit for speed).
- Convert to target unit: The m/s value is then converted to the desired output unit.
- Apply conversion factor: Each unit has a defined relationship based on distance and time units.
Conversion Formulas
1 km/h = 0.277778 m/s (1000m ÷ 3600s)
1 mph = 0.44704 m/s (exactly)
1 ft/s = 0.3048 m/s (exactly)
1 knot = 0.514444 m/s (1852m ÷ 3600s)
1 Mach = 343 m/s (at 20°C, sea level)
Common conversions:
1 km/h = 0.621371 mph
1 mph = 1.60934 km/h
1 knot = 1.852 km/h = 1.15078 mph
Common Speed Conversions
- km/h to mph: Multiply by 0.621371 (100 km/h = 62.14 mph)
- mph to km/h: Multiply by 1.60934 (60 mph = 96.56 km/h)
- m/s to km/h: Multiply by 3.6 (10 m/s = 36 km/h)
- knots to km/h: Multiply by 1.852 (100 knots = 185.2 km/h)
- knots to mph: Multiply by 1.15078 (100 knots = 115.08 mph)
Benefits of Using This Converter
- Travel planning: Understand speed limits when traveling internationally.
- Aviation and maritime: Convert between knots and ground speed units.
- Physics calculations: Convert to m/s for scientific computations.
- Instant results: Real-time conversion as you type.
- High precision: Uses exact conversion factors from international standards.
Understanding Speed Units
Kilometers per hour (km/h): The standard unit for road speed in most countries. Used on speedometers and road signs worldwide except in the US, UK, and a few other nations.
Miles per hour (mph): Used for road speed in the United States, United Kingdom, and associated territories. One mile equals exactly 1.609344 kilometers.
Meters per second (m/s): The SI unit for speed. Used in physics and engineering calculations. To convert km/h to m/s, divide by 3.6.
Knot: One nautical mile per hour. Used in maritime and aviation because nautical miles relate directly to latitude coordinates on navigation charts.
Mach: Speed relative to the speed of sound. Mach 1 is the speed of sound (~343 m/s at sea level). Used in aerospace and high-speed aviation.
Frequently Asked Questions
How do I quickly estimate km/h to mph?
Multiply km/h by 0.6 for a quick estimate. For example, 100 km/h ≈ 60 mph (actual: 62.14 mph). This approximation is within 3% accuracy.
What speed is Mach 1?
Mach 1 (the speed of sound) is approximately 343 m/s, 1,235 km/h, or 767 mph at sea level and 20°C. The exact speed varies with temperature and altitude—it's slower in colder air.
Why do pilots use knots instead of km/h?
Pilots use knots because 1 nautical mile equals 1 minute of latitude. This makes navigation calculations much simpler when working with latitude/longitude coordinates on aeronautical charts.
What's the fastest speed ever recorded by a human?
The crew of Apollo 10 reached 39,897 km/h (24,791 mph) during re-entry in 1969. On land, the ThrustSSC reached 1,228 km/h (763 mph) in 1997.
How do speed limits compare internationally?
Common highway limits: Germany (no limit on some autobahns), UK/US (~70 mph/113 km/h), France (130 km/h), Japan (100 km/h), Australia (110-130 km/h). Always check local regulations.
What does "ground speed" mean in aviation?
Ground speed is the aircraft's speed relative to the ground. It differs from airspeed (speed through the air) due to wind. A headwind reduces ground speed; a tailwind increases it.