What is this converter?
Converts speed between metres per second, kilometres per hour, miles per hour, feet per second, and knots. All conversions pass through metres per second, the SI derived unit.
Use it when:
- A speed limit, wind reading, or specification uses units you do not work in.
- You are converting a nautical or aviation speed given in knots.
- You need metres per second for a physics calculation.
Intended for: Drivers, sailors, pilots, athletes, and students of physics.
How is this calculated?
- Each supported unit is defined by a fixed conversion factor relative to one base unit for the quantity (for example, the metre for length).
- The value you enter is first converted from the source unit into that base unit by multiplying by the source unit's factor.
- The base value is then converted into the target unit by dividing by the target unit's factor.
- Because both factors are exact constants, the conversion is a single deterministic multiplication and division — the same input always produces the same output.
Example
Converting 100 kilometres per hour to miles per hour.
- 1 km/h is 1,000 metres per 3,600 seconds ≈ 0.2778 m/s.
- 1 mph ≈ 0.44704 m/s.
- 100 × 0.2778 ÷ 0.44704 ≈ 62.14.
Result: 100 km/h ≈ 62.14 mph.
Frequently asked questions
What exactly is a knot?
One nautical mile per hour, where a nautical mile is 1,852 metres — about 1.852 km/h. It persists in marine and aviation use because a nautical mile corresponds to one minute of latitude.
How do I convert km/h to m/s quickly in my head?
Divide by 3.6. It comes from 1,000 metres divided by 3,600 seconds.
Assumptions
What this converter takes as given:
- Conversion factors are the internationally standardised definitions of each unit, not regional or historical variants.
- The value you enter is treated as an exact quantity — no measurement uncertainty is carried through the conversion.
- Results are rounded only for display; the underlying arithmetic uses full precision.
Limitations
What this converter cannot know or does not model:
- The converter does not know the precision of your original measurement, so it cannot report significant figures for you.
- Units that share a name but differ by region or era (for example, different definitions of a gallon or a ton) are offered only in the variants listed in the unit menu.
- Very large or very small magnitudes are subject to the limits of double-precision floating-point arithmetic.