Speed Converter

Convert km/h, mph, m/s, knots, and feet per second

💡 Tip: Press Ctrl+D for dark mode, Ctrl+K to focus converter

🏃 Speed Converter

Convert between km/h, mph, meters per second, knots, and more

💡 Quick Tip: 100 km/h ≈ 62 mph
100 km/h = 62.1371 mph

Speed Conversion Guide

Common Speed Conversions

km/h mph m/s Knots Context
10 6.2 2.8 5.4 Jogging pace
30 18.6 8.3 16.2 City speed limit
50 31.1 13.9 27 Suburban road
100 62.1 27.8 54 Highway speed
120 74.6 33.3 64.8 Motorway limit
200 124.3 55.6 108 High-speed train
300 186.4 83.3 162 Racing car
900 559.2 250 486 Airplane cruise
1,225 761.2 340.3 661 Speed of sound

Understanding Speed Units

Kilometers Per Hour (km/h)

Used in: Most of the world (metric system)

Definition: The number of kilometers traveled in one hour

Common uses: Road speed limits, vehicle speedometers, weather reports (wind speed)

Abbreviations: km/h, kph, kmph

Miles Per Hour (mph)

Used in: United States, United Kingdom (for road speeds)

Definition: The number of miles traveled in one hour

Common uses: Road speed limits, vehicle speeds in US/UK

Conversion: 1 mph = 1.60934 km/h

Meters Per Second (m/s)

Used in: Science, physics, engineering

Definition: The number of meters traveled in one second

Common uses: Scientific calculations, athletics (running speed), physics problems

Conversion: 1 m/s = 3.6 km/h

Knots (kn)

Used in: Maritime and aviation industries

Definition: One nautical mile per hour (1 nautical mile = 1.852 km)

Common uses: Ship speeds, aircraft speeds, wind speeds at sea

Conversion: 1 knot = 1.852 km/h = 1.15078 mph

Origin: Named after the practice of using a knotted rope to measure ship speed

Feet Per Second (ft/s)

Used in: United States (engineering, ballistics)

Definition: The number of feet traveled in one second

Common uses: Projectile speeds, some engineering calculations

Conversion: 1 ft/s = 1.09728 km/h = 0.681818 mph

Practical Speed Examples

  • 🚶 Walking: 5 km/h (3.1 mph)
  • 🏃 Running (average): 12 km/h (7.5 mph)
  • 🚴 Cycling: 20-30 km/h (12-19 mph)
  • 🏎️ F1 Race Car: ~350 km/h (217 mph)
  • 🚄 Bullet Train: 320 km/h (200 mph)
  • ✈️ Commercial Jet: 900 km/h (560 mph)
  • 🚁 Helicopter: 250 km/h (155 mph)
  • ⛵ Sailboat: 15-20 knots
  • 🚢 Cruise Ship: 20-25 knots
  • 🐆 Cheetah: 120 km/h (75 mph)
  • 🦅 Peregrine Falcon (dive): 390 km/h (240 mph)
  • 💨 Hurricane Winds: 120+ km/h (74+ mph)
  • 🔊 Speed of Sound: 1,225 km/h (761 mph at sea level)

Conversion Formulas

KM/H to MPH:

mph = km/h ÷ 1.60934
or
mph = km/h × 0.621371

MPH to KM/H:

km/h = mph × 1.60934

KM/H to M/S:

m/s = km/h ÷ 3.6

M/S to KM/H:

km/h = m/s × 3.6

Knots to KM/H:

km/h = knots × 1.852

Knots to MPH:

mph = knots × 1.15078

Why Different Speed Units?

Different speed units evolved for different purposes:

  • 🚗 KM/H: Part of the metric system - logical, decimal-based
  • 🇺🇸 MPH: Traditional in countries using imperial measurements
  • 🔬 M/S: SI unit - fundamental for physics and scientific calculations
  • ⚓ Knots: Based on nautical miles, ideal for marine/aviation navigation
  • 🎯 FT/S: Imperial unit for engineering and ballistics

Quick Mental Math Tips

KM/H to MPH (approximate):

  • Divide km/h by 1.6 (or multiply by 0.6) → Example: 100 km/h ÷ 1.6 ≈ 62.5 mph ✓
  • Even quicker: Multiply by 6, then divide by 10 → 100 × 6 = 600 ÷ 10 = 60 mph

MPH to KM/H (approximate):

  • Multiply mph by 1.6 → Example: 60 mph × 1.6 = 96 km/h ✓
  • Even quicker: Add half the value → 60 + 30 = 90 km/h (close enough!)

KM/H to M/S:

  • Divide by 3.6 → Example: 36 km/h ÷ 3.6 = 10 m/s ✓
  • Quick rule: Drop the last digit and divide by 3.6

M/S to KM/H:

  • Multiply by 3.6 → Example: 10 m/s × 3.6 = 36 km/h ✓

Speed Limits Around the World

Highway/Motorway Speed Limits:

  • 🇩🇪 Germany (Autobahn): No general limit (advisory 130 km/h / 81 mph)
  • 🇮🇹 Italy: 130 km/h (81 mph)
  • 🇫🇷 France: 130 km/h (81 mph)
  • 🇬🇧 UK: 70 mph (112 km/h)
  • 🇺🇸 USA: 55-85 mph (88-137 km/h, varies by state)
  • 🇨🇦 Canada: 100-110 km/h (62-68 mph)
  • 🇦🇺 Australia: 100-110 km/h (62-68 mph)
  • 🇯🇵 Japan: 100 km/h (62 mph)
  • 🇨🇳 China: 120 km/h (75 mph)

Frequently Asked Questions

How do I convert km/h to mph?

Divide kilometers per hour by 1.60934 (or multiply by 0.621371). For example, 100 km/h ÷ 1.60934 = 62.14 mph. For quick mental math, divide by 1.6 or multiply by 0.6.

How many mph is 100 km/h?

100 km/h equals 62.1371 mph. This is a common conversion since many highways have 100 km/h limits, equivalent to about 62 mph.

What is a knot in speed?

A knot is one nautical mile per hour. It equals 1.852 km/h or 1.15078 mph. Knots are used primarily in maritime and aviation contexts because nautical miles align with latitude/longitude navigation.

How do I convert m/s to km/h?

Multiply meters per second by 3.6. For example, 10 m/s × 3.6 = 36 km/h. This works because 1 hour = 3,600 seconds and 1 km = 1,000 meters, so 3,600/1,000 = 3.6.

Why does aviation use knots instead of km/h or mph?

Nautical miles align directly with latitude and longitude (1 nautical mile = 1 minute of latitude), making navigation calculations simpler. This standard was adopted by aviation from maritime use.

What is the speed of sound in different units?

At sea level and 15°C, the speed of sound is approximately 1,225 km/h, 761 mph, 340 m/s, or 661 knots. This varies with altitude and temperature - it's slower at higher, colder altitudes.

Quick Reference Chart

1 KM/H equals:

  • 0.621371 mph
  • 0.277778 m/s
  • 0.539957 knots
  • 0.911344 ft/s

1 MPH equals:

  • 1.60934 km/h
  • 0.44704 m/s
  • 0.868976 knots
  • 1.46667 ft/s

1 M/S equals:

  • 3.6 km/h
  • 2.23694 mph
  • 1.94384 knots
  • 3.28084 ft/s

1 Knot equals:

  • 1.852 km/h
  • 1.15078 mph
  • 0.514444 m/s
  • 1.68781 ft/s