Speed conversion
Use m/s as the canonical basis for km/h, mph, knots, and ft/s. As quick references, 1 m/s=3.6 km/h and 100 km/h is about 62.14 mph.
057 · UNIT & CALCULATOR
Speed, Fuel Economy & Energy Converter
Convert speed, fuel economy, energy, power, and horsepower units and compare common equivalents.
LOCALCALCULATE IN YOUR BROWSER
LOCALValues and conversion results are calculated only in this browser and are not sent to or stored on a server.
Quick units
Display settings · Precision
6
RESULT · Conversion result
62.137119mph
100 km/h → mph
Common unit results
100Kilometers/hour · km/h
62.137119Miles/hour · mph
27.777778Meters/second · m/s
53.99568Knot · kn
91.134442Feet/second · ft/s
HOW TO USE
How to use
- 01
Choose Speed, Fuel Economy, Energy, or Power.
- 02
Enter a value and select the From and To units.
- 03
Review the main conversion and common equivalents together.
- 04
For fuel economy, note the US/UK MPG difference and the reversed L/100km direction.
- 05
Adjust display precision or copy the current result when needed.
CONVERSION GUIDE
Speed, fuel economy, energy, and power use different conversion structures
Speed uses m/s, energy uses joules, power uses watts, and fuel economy uses reciprocal conversions around km/L.Fuel economy is reciprocal
Higher km/L means better economy, while lower L/100km means better economy. They are linked by a reciprocal relationship rather than simple multiplication.
US vs UK MPG
A US gallon and an imperial gallon have different volumes, so identical MPG numbers are not equivalent. The tool keeps US MPG and UK MPG separate.
Energy
J, Wh, and kWh measure an amount of energy. The conversion uses 1 Wh=3600 J and 1 kWh=1000 Wh.
Power and horsepower
W and kW express a rate of energy use, while hp and PS are horsepower units. hp and PS use different conversion factors and are handled separately.
Energy is not power
kWh and kW look similar but measure different dimensions. Energy is an amount; power is a rate, so this tool does not directly convert one into the other.
IMPORTANT NOTES
Important notes
- Speed uses m/s, energy uses J, and power uses W as internal canonical units.
- Fuel economy uses reciprocal conversion around km/L; L/100km runs in the opposite direction.
- US and UK MPG differ because the gallon sizes differ.
- kW is power while kWh is energy, so they are kept in separate groups.
- Mechanical hp and metric PS are separate horsepower units.
- Rounding is applied only for display; internal calculation values are preserved.
FAQ
Frequently asked questions
01How many mph is 100 km/h?+
About 62.1371 mph; common equivalents such as m/s and knots are shown together.
02What is 30 US MPG in L/100km?+
About 7.84 L/100km. MPG and L/100km use opposite efficiency directions.
03Why do US MPG and UK MPG differ?+
The US gallon and Imperial gallon have different volumes.
04Can I convert kW directly to kWh?+
No. kW is power and kWh is energy, so time is required to relate them.
05Are hp and PS the same?+
No. Mechanical hp and metric PS use different watt factors.