Free Speed Converter

Speed limits switch between mph and km/h at every border, sailors think in knots, and runners think in minutes per mile. This free speed converter handles them all — road, marine, aviation and physics units — converting instantly with a complete comparison table.

ℹ️Mach 1 is about 1,225 km/h at sea level (15 °C); it varies with altitude and temperature.
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Value in all speed units

UnitValue
Private by design. This tool runs 100% in your browser — nothing is uploaded to any server.

How to Use the Speed Converter

  1. Enter a value in the input box above.
  2. Choose the units to convert from and to — use the ⇄ button to swap them instantly.
  3. See the result immediately, plus the value converted into every other speed unit in the table below.
  4. Copy the result with one click to use it anywhere.

Features

Six speed units: km/h, m/s, mph, ft/s, knots and Mach. Results update as you type, the swap button reverses direction instantly, and every equivalent appears in the table below.

Benefits & Use Cases

Drivers abroad, pilots, sailors, cyclists and physics students all get trustworthy numbers in one step. Mach conversions use sea-level standard conditions, noted clearly so you know the assumption.

Tips

To estimate mph from km/h, multiply by 0.6 (100 km/h ≈ 62 mph — close to the true 62.1). One knot is one nautical mile per hour, about 1.852 km/h.

Frequently Asked Questions

How do I convert km/h to mph?

Multiply by 0.621371. For example, 100 km/h = 62.14 mph.

How fast is one knot in km/h?

Exactly 1.852 km/h.

What speed is Mach 1?

About 1,225 km/h (761 mph) at sea level at 15 °C. It drops with altitude as air temperature falls.

How many m/s is 100 km/h?

27.78 m/s — divide km/h by 3.6.

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