Kilometer Per Hour Calculator
Calculate speed, distance, or time and convert between speed units
Table of Contents
How to Use
- Select what you want to calculate: speed, distance, or time
- Enter the known values with their appropriate units
- Select the unit for your desired result
- Click calculate to see the result with conversion formulas
- View all speed unit equivalents for reference
Speed, Distance, and Time
The relationship between speed, distance, and time is one of the fundamental concepts in physics and everyday life. These three variables are interconnected through simple mathematical relationships that allow you to calculate any one when you know the other two.
Understanding these relationships is essential for travel planning, sports analysis, engineering calculations, and many other practical applications.
Basic Formulas
- Speed = Distance ÷ Time
- Distance = Speed × Time
- Time = Distance ÷ Speed
These formulas assume constant speed (no acceleration or deceleration). In real-world scenarios, speeds often vary, so these calculations provide average values.
Common Speed Units
| Unit | Symbol | km/h Equivalent | Common Use |
|---|---|---|---|
| Kilometers per hour | km/h | 1 km/h | Road signs, cars (metric countries) |
| Miles per hour | mph | 1.609 km/h | Road signs, cars (US, UK) |
| Meters per second | m/s | 3.6 km/h | Physics, athletics |
| Knots | kn | 1.852 km/h | Aviation, maritime |
| Feet per second | ft/s | 1.097 km/h | Engineering, ballistics |
Distance Units
| Unit | Symbol | Meter Equivalent | Common Use |
|---|---|---|---|
| Kilometer | km | 1,000 m | Long distances, road travel |
| Mile | mi | 1,609.34 m | Long distances (US, UK) |
| Meter | m | 1 m | SI base unit, everyday measurements |
| Foot | ft | 0.3048 m | Height, short distances (US) |
Time Units
| Unit | Symbol | Hour Equivalent | Common Use |
|---|---|---|---|
| Hour | h | 1 h | Long durations, travel time |
| Minute | min | 1/60 h | Short durations, precise timing |
| Second | s | 1/3600 h | Very short durations, physics |
Practical Examples
- Car travel: If you drive 100 km in 2 hours, your average speed is 50 km/h
- Running: If you run 5 km in 25 minutes, your average speed is 12 km/h
- Flight time: If a plane flies 800 km at 400 km/h, the flight takes 2 hours
- Walking: If you walk 3 miles in 1 hour, your walking speed is 3 mph
Quick Conversion Tips
- km/h to mph: Multiply by 0.621 (or divide by 1.609)
- mph to km/h: Multiply by 1.609 (or divide by 0.621)
- km/h to m/s: Divide by 3.6
- m/s to km/h: Multiply by 3.6
- km/h to knots: Divide by 1.852
- knots to km/h: Multiply by 1.852
Frequently Asked Questions
- What's the difference between speed and velocity?
- Speed is a scalar quantity that only considers magnitude (how fast), while velocity is a vector quantity that includes both magnitude and direction. In everyday language, we often use 'speed' and 'velocity' interchangeably, but in physics, velocity includes the direction of movement.
- How do I convert between different speed units?
- Use the conversion factors: 1 km/h = 0.621 mph = 0.278 m/s = 0.540 knots = 0.911 ft/s. The calculator handles all conversions automatically, but knowing these relationships helps with quick mental calculations.
- Why do these calculations assume constant speed?
- The basic formulas (speed = distance/time) assume constant velocity for simplicity. In reality, most travel involves acceleration, deceleration, and speed changes. These calculations give you average speed, which is useful for planning and estimation purposes.
- How accurate are these calculations for real-world travel?
- These calculations provide theoretical values based on constant speed. Real-world factors like traffic, stops, acceleration, and varying road conditions will affect actual travel times. Use these as estimates and add buffer time for practical planning.
- What's the fastest land speed ever recorded?
- The fastest land speed record is held by the ThrustSSC, which reached 1,227.985 km/h (763.035 mph) in 1997. This is significantly faster than typical road vehicles, which usually travel between 50-120 km/h (30-75 mph) on highways.