Instantly convert between 27 speed units — metric, imperial, knots, Beaufort scale, and running pace. Real-time results.
Americans primarily measure speed in miles per hour (mph). NASCAR Daytona 500 superspeedway cars reach up to 200 mph (321.9 km/h = 89.4 m/s). Major League Baseball four-seam fastballs top out around 100 mph (160.9 km/h = 44.7 m/s) — Aroldis Chapman threw a verified 105.1 mph (169.1 km/h, 47.0 m/s) pitch in 2010. US interstate highways post a maximum of 80 mph (128.7 km/h) in some states. The Space Shuttle reentered Earth's atmosphere at ~17,500 mph (28,163 km/h = 7.82 km/s ≈ 0.000026c).
This converter handles 27 units in four groups: Metric, Imperial/US, Other (knots, Beaufort, speed of light), and Running Pace. All conversions use meters per second (m/s) as the internal base unit. The Beaufort scale uses a non-linear power formula; running pace units are the reciprocal of speed.
All linear units convert through a constant factor f (where 1 unit = f m/s). The general formula is:
Linear units (all except Beaufort and running pace):
Beaufort scale (non-linear power formula):
Running pace units (reciprocal speed, where d is distance in meters):
Where f_source is the m/s value per one source unit, and f_target is the same for the target unit. The converter first converts to m/s, then to the target unit.
At Daytona International Speedway, Cup Series cars reach drafting speeds of 195–200 mph (313.8–321.9 km/h = 87.2–89.4 m/s = 169.4–173.8 knots). The track record was set by Bill Elliott at 210.364 mph (338.5 km/h = 94.0 m/s) in 1987 qualifying. Restrictor plates cap top speeds today for safety. Conversion: 200 mph × 1.60934 = 321.9 km/h ÷ 3.6 = 89.4 m/s.
A 100 mph (160.9 km/h = 44.7 m/s) fastball travels from the pitcher's mound to home plate (60.5 ft = 18.44 m) in approximately 0.41 seconds. Aroldis Chapman's 2010 record pitch was 105.1 mph (169.1 km/h = 47.0 m/s). For comparison, a 90 mph pitch = 144.8 km/h = 40.2 m/s. Home run exit velocities typically range 105–120 mph (168.9–193.1 km/h).
Modern America's Cup AC75 foiling monohulls reach speeds exceeding 50 knots (92.6 km/h = 25.7 m/s = 57.5 mph) downwind in 15–20 knots of breeze. The last AC72 catamarans hit over 47 knots (87 km/h) in San Francisco Bay in 2013. Conversion: 50 knots × 1.852 = 92.6 km/h = 25.72 m/s.
The Boston Marathon (26.2 miles = 42.195 km) is the world's oldest annual marathon (since 1897). Course record: Sisay Lemma, 2:06:17 in 2024 = ~2:59 min/km (179 s/km) = 20.1 km/h (5.6 m/s). In US terms: 4:34 min/mile pace. A 4-hour finisher maintains 9:09 min/mile (5:41 min/km) = 10.5 km/h (2.9 m/s).
Enter a numeric value in the input field. Positive numbers, decimals, and very large or small values are all supported.
Select the source unit from the dropdown menu. All 27 units are listed with their full name and symbol.
The converter translates your value to meters per second (m/s) via the unit's conversion factor — or via Beaufort's power formula, or via the reciprocal formula for running pace.
Results are shown in five sections: Primary Units and expandable groups for Metric, Imperial, Other, and Running Pace.
All conversions update in real time as you type. Extremely large or small values are displayed in scientific notation.
Quick mph ↔ km/h rule: multiply mph by 1.609 for km/h, or divide km/h by 1.609 for mph. Example: 60 mph = 96.6 km/h; 100 km/h ≈ 62.1 mph.
Knots to mph: multiply knots by 1.151. A Beaufort 8 gale = 17.2–20.7 m/s = 33.4–40.2 knots = 38.4–46.3 mph.
Running pace (min/mile to mph): divide 60 by the pace in minutes per mile. A 9:00 min/mile = 60 ÷ 9 = 6.67 mph. Or flip: at 8 mph your pace is 7:30 min/mile.
Speed of sound at sea level, 68°F (20°C) ≈ 767 mph (1,235 km/h = 343 m/s). Mach 1 at sea level = 767 mph. The SR-71 Blackbird's top speed was Mach 3.3 ≈ 2,532 mph.
The International Space Station orbits at ~17,500 mph (28,163 km/h = 7.82 km/s), completing one orbit every ~92 minutes.
Speed is a scalar — it describes how fast an object is moving without specifying direction (e.g., 60 mph). Velocity is a vector — it includes both magnitude and direction (e.g., 60 mph due north). When converting units, only the scalar magnitude matters.
Running pace (min/mile or min/km) is the reciprocal of speed: pace = time ÷ distance. The faster you run, the fewer minutes per mile — so the pace value decreases. A 6:00/mile pace is faster than 7:00/mile. At 10 mph, your pace is 6:00/mile; at 8 mph, it's 7:30/mile.
One knot equals one nautical mile per hour (1.151 mph = 1.852 km/h). A nautical mile (6,076 feet = 1,852 m) corresponds to one minute of arc of latitude, making it a natural unit for navigation with charts and GPS coordinates — which is why pilots and sailors worldwide use it.
The Beaufort scale (0–12) was devised in 1805 by British-Irish Admiral Francis Beaufort to estimate wind strength from visible effects on the sea surface. The modern formula is v = 0.836 × B^1.5 m/s. For example: Beaufort 10 ('storm') = 0.836 × 10^1.5 ≈ 26.4 m/s = 59.1 mph.
No. According to Einstein's special theory of relativity, no object with mass can reach or exceed the speed of light in a vacuum (c ≈ 186,282 miles per second = 299,792,458 m/s). Only massless particles like photons travel at exactly c in a vacuum.
The US and UK historically adopted imperial measurements before the metric system became internationally dominant. Traffic laws, speedometers, and road signs were built around miles, and changing them would require enormous infrastructure and legislative overhaul. Most other countries switched to km/h during the 20th century.
All conversions use exact or internationally defined conversion factors (e.g., 1 inch = 0.0254 m exactly, 1 nautical mile = 1,852 m exactly, 1 international mile = 1,609.344 m exactly). The Beaufort formula is an empirical approximation. Running pace values are the mathematical reciprocal of speed and assume uniform linear motion.