Speed & Velocity Converter

Quick Reference Table

From	To	Multiply By	Example
MPH	KPH	1.60934	60 mph = 96.56 kph
KPH	MPH	0.621371	100 kph = 62.14 mph
Knots	MPH	1.15078	100 knots = 115.08 mph
Knots	KPH	1.852	100 knots = 185.2 kph
M/S	KPH	3.6	10 m/s = 36 kph
Mach	MPH	767.269	Mach 1 = 767.27 mph

Common Speed Benchmarks

Description	MPH	KPH	M/S
Walking speed	3.1	5	1.4
Running speed	12.4	20	5.6
City speed limit	30	48	13.4
Highway speed limit	65-70	105-113	29-31
Cheetah (fastest land)	70	113	31
High-speed train	200	322	89
Commercial aircraft	550	885	246
Speed of sound (Mach 1)	767	1,235	343
Space Shuttle reentry	17,500	28,000	7,800

Understanding Speed & Velocity Units

Miles Per Hour (mph)

Definition: The number of statute miles traveled in one hour. One mile equals 5,280 feet or 1.60934 kilometers.

History: Developed with the imperial system, standardized alongside the statute mile in the British Weights and Measures Act. Became the dominant speed unit in English-speaking countries.

Current Use: Primary speed unit in the United States, United Kingdom (alongside kph), and several Commonwealth nations. Used on road signs, speedometers, weather reports (wind speed), and aviation in these countries. US highway speed limits typically range from 55-80 mph.

Kilometers Per Hour (kph or km/h)

Definition: The number of kilometers traveled in one hour. One kilometer equals 1,000 meters or 0.621371 miles.

History: Emerged with the metric system in revolutionary France. Became internationally standardized as countries adopted the metric system throughout the 19th and 20th centuries.

Current Use: Official speed unit in most countries worldwide. Used on road signs, speedometers, weather forecasts, and transportation systems in over 95% of nations. Standard speed limits vary: urban areas 50 kph, highways 80-130 kph depending on country.

Meters Per Second (m/s)

Definition: The SI unit of speed - the number of meters traveled in one second. One m/s equals 3.6 kph or 2.237 mph.

History: The fundamental SI unit for velocity, derived from the base units meter and second. Adopted with the modern metric system and International System of Units.

Current Use: Primary unit in physics, engineering, and scientific research. Used in wind speed measurements (meteorology), projectile motion calculations, particle physics, and athletic performance analysis (sprint speeds). Not commonly used for vehicle speeds in everyday contexts.

Knots (kn or kt)

Definition: One nautical mile per hour. A nautical mile equals exactly 1,852 meters or approximately 1.15078 statute miles. One knot = 1.852 kph.

History: Named after the practice of measuring ship speed by throwing a knotted rope overboard and counting knots passing through hands in a specific time. Based on nautical miles, which relate to Earth's geometry (one minute of latitude).

Current Use: Universal speed unit in maritime navigation and aviation worldwide. All ships and aircraft use knots for speed regardless of country. Weather reports often give wind speeds in knots. International standard in navigation because nautical miles directly correspond to coordinates on navigation charts.

Mach Number

Definition: Ratio of an object's speed to the speed of sound in the surrounding medium. Mach 1 = speed of sound (approximately 767 mph or 1,235 kph at sea level, 15°C). Mach 2 = twice the speed of sound, etc.

History: Named after Austrian physicist Ernst Mach (1838-1916) who studied supersonic motion and shock waves. Became crucial in aviation as aircraft approached and exceeded the sound barrier in the 1940s.

Current Use: Used primarily in aerospace and military aviation for high-speed aircraft. Commercial supersonic flights (Concorde) cruised at Mach 2. Fighter jets operate from subsonic (below Mach 1) to supersonic (Mach 1-5) and hypersonic (above Mach 5). Note: Speed of sound varies with temperature and altitude.

Speed of Light (c)

Definition: The fastest speed possible in the universe: exactly 299,792,458 meters per second, approximately 186,282 miles per second, or about 671 million mph.

History: Measured and refined over centuries. In 1983, the speed of light was fixed as a defined constant, with the meter redefined based on it. Fundamental to Einstein's theory of relativity.

Current Use: Used in physics, astronomy, and telecommunications. Relevant for understanding cosmic distances (light-years), GPS satellite timing, fiber optic communications, and theoretical physics. Nothing with mass can reach light speed.

Feet Per Second (ft/s or fps)

Definition: The number of feet traveled in one second. One ft/s equals 0.681818 mph or 0.3048 m/s.

History: Traditional imperial unit used in engineering and ballistics before metrication.

Current Use: Still used in some US engineering contexts, ballistics (bullet velocities), and sports (baseball pitch speeds). Mostly replaced by m/s in scientific contexts. Skydiving terminal velocity is about 120 mph or 176 ft/s.

Frequently Asked Questions

How do I convert mph to kph?

Multiply mph by 1.60934. Formula: kph = mph × 1.60934. Example: 60 mph × 1.60934 = 96.56 kph. Quick estimate: multiply by 1.6 (60 mph ≈ 96 kph). To convert kph to mph, divide by 1.60934 or multiply by 0.621371.

How do I convert knots to mph?

Multiply knots by 1.15078. Formula: mph = knots × 1.15078. Example: 100 knots × 1.15078 = 115.08 mph. For knots to kph, multiply by 1.852 (100 knots = 185.2 kph).

What is Mach 1 in mph?

Mach 1 (the speed of sound) is approximately 767 mph or 1,235 kph at sea level at 15°C (59°F). However, the speed of sound varies with temperature and altitude. At higher altitudes where air is colder, the speed of sound decreases to about 660 mph.

Why do planes and ships use knots?

Knots are based on nautical miles, which directly relate to Earth's coordinates. One nautical mile equals one minute of latitude, making navigation calculations simpler. Charts use latitude/longitude, so using knots and nautical miles keeps distance and speed measurements consistent with navigation systems.

How fast is the speed of light?

The speed of light in a vacuum is exactly 299,792,458 m/s, approximately 186,282 miles per second, or about 671 million mph. Light travels from Earth to the Moon in about 1.3 seconds and from the Sun to Earth in about 8 minutes 20 seconds.

What's the difference between mph and kph?

Both measure distance traveled per hour, but use different distance units. MPH uses statute miles (5,280 feet), while kph uses kilometers (1,000 meters). 1 mph = 1.60934 kph, so kph is the smaller unit - 100 kph is slower than 100 mph (62 mph equivalent).

Can anything go faster than light?

No. According to Einstein's theory of relativity, nothing with mass can reach or exceed the speed of light in a vacuum. As objects approach light speed, their mass effectively increases, requiring infinite energy to reach c. Light speed is the cosmic speed limit.

How do I convert m/s to mph?

Multiply m/s by 2.237. Formula: mph = m/s × 2.237. Example: 10 m/s × 2.237 = 22.37 mph. For m/s to kph, multiply by 3.6 (10 m/s = 36 kph).

Common Uses for Speed Conversion

• International Travel: Understanding speed limits when driving in different countries
• Aviation & Maritime: Converting between knots and other units for navigation
• Sports & Fitness: Converting running pace, cycling speed, or swim times
• Weather Reports: Understanding wind speeds from different sources
• Vehicle Specifications: Comparing car performance specs internationally
• Science & Education: Physics problems and engineering calculations
• Transportation Planning: Converting speed data for infrastructure projects
• Aerospace: Understanding aircraft specifications and performance

Speed Conversion Tips

1. Quick mph to kph: Multiply by 1.6 for a close estimate (exact: 1.60934)
2. Quick kph to mph: Divide by 1.6 or multiply by 0.6 for approximation
3. Remember key benchmarks: 60 mph ≈ 100 kph, 100 mph ≈ 160 kph
4. Knots are faster than mph: 100 knots = 115 mph, not 100 mph
5. Speed of sound varies: Mach 1 changes with temperature and altitude
6. Use correct abbreviations: mph (or mi/h), kph (or km/h), m/s, kt
7. Aviation always uses knots: Even in mph countries like the US

Interesting Speed Facts

• Usain Bolt's top speed: 27.8 mph (44.72 kph) - world's fastest human
• Cheetah top speed: 70 mph (113 kph) - fastest land animal
• Peregrine falcon dive: 240 mph (386 kph) - fastest bird
• Formula 1 top speed: ~230 mph (370 kph)
• Bullet train (Japan): 200 mph (320 kph)
• Commercial jet cruise: 550 mph (885 kph)
• Concorde cruise speed: Mach 2.04 (1,354 mph)
• SR-71 Blackbird: Mach 3.3 (2,200+ mph) - fastest jet
• Apollo 10 reentry: 24,791 mph - fastest human travel
• Earth's orbit around Sun: 67,000 mph (108,000 kph)
• Milky Way through space: 1.3 million mph (2.1 million kph)