Speed Converter
Convert between common speed and velocity units instantly. Enter a value, choose your unit, and see all conversions at once.
How to Use the Speed Converter
Converting between speed units takes just a few steps:
- Enter a speed value in the input field. Decimals are fully supported.
- Select the source unit from the dropdown (m/s, km/h, mph, knots, ft/s, or Mach).
- View all conversions instantly in the results table. The tool calculates as you type.
- Click Copy next to any result to copy it to your clipboard.
About Speed Units
Speed measures how quickly an object changes its position. The SI unit is meters per second (m/s), but kilometers per hour (km/h) and miles per hour (mph) are far more common in daily life. Knots, used in aviation and maritime contexts, equal one nautical mile per hour. The Mach number represents speed relative to the speed of sound, approximately 343 m/s at sea level.
Key conversions include: 1 km/h = 0.27778 m/s, 1 mph = 0.44704 m/s, 1 knot = 0.51444 m/s, and Mach 1 = 343 m/s (at standard conditions). These conversions are vital for driving, aviation, weather forecasting, physics, and sports science.
Common Speed Conversions
The table below provides a quick reference for frequently searched speed conversions. These values cover common speed limits, athletic performances, and notable velocities.
| km/h | mph | m/s | Knots | Context |
|---|---|---|---|---|
| 10 | 6.21 | 2.78 | 5.40 | Jogging pace |
| 30 | 18.64 | 8.33 | 16.20 | Residential speed limit |
| 50 | 31.07 | 13.89 | 27.00 | City speed limit |
| 100 | 62.14 | 27.78 | 53.99 | Highway speed limit |
| 120 | 74.56 | 33.33 | 64.79 | Autobahn advisory |
| 200 | 124.27 | 55.56 | 107.99 | High-speed rail |
| 1,235 | 767 | 343 | 667 | Speed of sound (Mach 1) |
Speed Conversion Formulas
All speed conversions pass through a common base unit (meters per second). The key conversion factors are listed below, followed by worked examples.
km/h to mph: mph = km/h × 0.621371
mph to km/h: km/h = mph × 1.60934
m/s to km/h: km/h = m/s × 3.6
Knots to mph: mph = knots × 1.15078
Knots to km/h: km/h = knots × 1.852
Worked Examples
- Convert 65 mph to km/h: km/h = 65 × 1.60934 = 104.61 km/h
- Convert 250 km/h to m/s: m/s = 250 ÷ 3.6 = 69.44 m/s
- Convert 30 knots to mph: mph = 30 × 1.15078 = 34.52 mph
- Convert 340 m/s to Mach: Mach = 340 ÷ 343 = 0.991 Mach (just under the speed of sound)
When You Need This Converter
Speed conversion arises in numerous real-world situations. Here are the most common scenarios:
- Driving Abroad: Speed limits and road signs differ by country. Most of the world uses km/h, while the US and UK use mph. Knowing that a 130 km/h speed limit equals about 81 mph helps you drive safely in unfamiliar countries without risking a speeding ticket.
- Aviation and Sailing: Pilots and sailors use knots as their standard speed unit because it ties directly to nautical miles, simplifying navigation calculations. Converting between knots and km/h or mph is a routine task in flight planning and marine navigation.
- Sports and Athletics: Running speeds, cycling speeds, and ball speeds are reported in different units around the world. A pitch thrown at 100 mph is 160.93 km/h, and a 10 km/h running pace equals about 6.21 mph. Comparing athletic performances across countries requires accurate speed conversion.
- Physics and Engineering: Scientific calculations use m/s as the standard speed unit. Engineers designing vehicles, machinery, or aerodynamic systems frequently convert between m/s, km/h, and Mach numbers to ensure specifications are met across different measurement standards.
Frequently Asked Questions
Divide the km/h value by 1.60934 to get mph, or multiply by 0.621371. For example, 100 km/h × 0.621371 = 62.14 mph.
Mach 1 is the speed of sound, approximately 343 m/s (1,235 km/h or 767 mph) at sea level and 20°C. Speeds above Mach 1 are called supersonic.
Knots are used in maritime and aviation navigation. One knot equals one nautical mile per hour, or approximately 1.852 km/h (1.15078 mph).
Multiply the mph value by 1.60934 to get km/h. For example, 60 mph = 60 × 1.60934 = 96.56 km/h.
The speed of light in a vacuum is approximately 299,792,458 m/s, which equals 1,079,252,849 km/h, 670,616,629 mph, or about Mach 874,030 at sea level.
100 km/h equals approximately 62.14 mph. This is a commonly searched conversion since 100 km/h is a standard highway speed limit in many countries.
Speed is a scalar quantity that measures how fast an object is moving regardless of direction. Velocity is a vector quantity that includes both speed and direction. For unit conversion purposes, the same conversion factors apply to both.
Multiply the m/s value by 3.6 to get km/h. This works because there are 3,600 seconds in an hour and 1,000 meters in a kilometer (3600/1000 = 3.6). For example, 10 m/s = 10 × 3.6 = 36 km/h.