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Speed Conversion Calculator.

Converts a speed value between common units: kilometers per hour, miles per hour, meters per second, and knots.

Results update live as you type.
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Your inputs

How it works

  1. 1

    Enter the speed value and select the unit you are converting from.

  2. 2

    Select the unit you want to convert to.

  3. 3

    The calculator converts the value using the appropriate conversion factor.

  4. 4

    The result is displayed with two decimal places.

speed_value * (from_unit == 'kmh' ? 1 : from_unit == 'mph' ? 1.609344 : from_unit == 'ms' ? 3.6 : 1.852) / (to_unit == 'kmh' ? 1 : to_unit == 'mph' ? 1.609344 : to_unit == 'ms' ? 3.6 : 1.852)

Frequently asked questions

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

Divide the speed in km/h by 3.6 to get m/s. For example, 100 km/h ÷ 3.6 = 27.78 m/s.

What is the difference between a knot and mph?

A knot is one nautical mile per hour, equal to 1.15078 mph. It is commonly used in aviation and maritime contexts.

Can I convert between any of these units?

Yes, the calculator supports conversions among km/h, mph, m/s, and knots. Simply select the from and to units.

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Converted speed

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How it works

Converts a speed value between common units: kilometers per hour, miles per hour, meters per second, and knots.

  1. Enter the speed value and select the unit you are converting from.
  2. Select the unit you want to convert to.
  3. The calculator converts the value using the appropriate conversion factor.
  4. The result is displayed with two decimal places.

Formulas

The math behind this calculator, written out so you can verify the result.

Conversion factor method

value_in_target = value_in_source × factor_source / factor_target

Each unit has a factor relative to km/h: km/h=1, mph=1.609344, m/s=3.6, knots=1.852. Multiply the input by the source factor and divide by the target factor.

Example:

Input: 100 km/h to mph

Calculation: 100 × 1 / 1.609344

Result: ≈ 62.14 mph

Real-world use cases

Where this calculation shows up in everyday life.

Running pace

Convert your treadmill speed from km/h to min/km or mph to understand your pace.

Example: If you run at 10 km/h, that's about 6.2 mph.

Cycling speed

Compare speeds when cycling in different countries or on different devices.

Example: A 25 km/h cycling speed is about 15.5 mph.

Aviation and marine

Convert between knots and other units for flight planning or sailing.

Example: A boat speed of 20 knots is about 37 km/h.

Tips and common mistakes

Tips

  • Remember: 1 m/s = 3.6 km/h, so to convert m/s to km/h multiply by 3.6.
  • For quick mental conversion, 1 mph ≈ 1.609 km/h, so multiply mph by 1.6 for a rough estimate.
  • Knots are used in navigation; 1 knot = 1 nautical mile per hour.
  • Always double-check your units when comparing speeds from different sources.

Common Mistakes to Avoid

  • Confusing m/s with km/h: forgetting to multiply or divide by 3.6.
  • Using the wrong conversion factor for knots (1 knot = 1.852 km/h, not 1.15).
  • Rounding too early in multi-step conversions, leading to inaccurate results.

Assumptions and limitations

  • Use the stated inputs and units.
  • Results are estimates for planning and education.
  • Check measurements and source data before making an important decision.