Physics Unit Converter
Convert force, energy, speed and power units instantly: newtons to pound-force, km/h to mph, horsepower to kW and more.
100 N =
22.480902lbf
Newton to pound-force
How this works: Method,
How this works
Method
Each unit is stored as its size in the SI unit for its quantity (newtons, joules, metres per second or watts), and value in the new unit = value × size of the old unit ÷ size of the new one. Ratios fixed by definition, such as 1 kWh = 3.6 MJ, are exact; a few units use standard rounded factors, such as 1 lbf = 4.44822 N and 1 metric horsepower = 735.5 W.
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Changes
- Redesigned: a ruler comparing your value with everyday things, common units as quick picks, the answer in other units at once, and corrected symbols such as pN for piconewton.
- First published.
Frequently Asked Questions
How do I convert between force units like Newtons and pound-force?
Force conversions use fixed ratios relative to the Newton (N), the SI unit. 1 pound-force (lbf) = 4.448 N, and 1 kilogram-force (kgf) = 9.807 N. Pick your source and target units and the converter applies the ratio instantly, with no manual maths.
What's the difference between energy units (Joule, calorie, BTU, kWh)?
They all measure energy but at very different scales. 1 calorie = 4.184 J, 1 BTU ≈ 1055 J, and 1 kilowatt-hour (kWh) = 3,600,000 J. kWh is used for electricity billing, calories for food/heat, and BTU for heating and cooling systems.
How is speed converted between m/s, km/h, mph, and knots?
All speeds convert through metres per second (m/s). 1 km/h = 0.2778 m/s, 1 mph = 0.4470 m/s, and 1 knot = 0.5144 m/s. So 100 km/h ≈ 27.8 m/s ≈ 62 mph.
What units does the power converter support?
It converts between Watts (W), kilowatts (kW), horsepower (hp), and BTU per hour. 1 hp ≈ 745.7 W and 1 kW ≈ 3412 BTU/hr. Power is the rate of energy transfer: energy per unit time.
Are these conversions exact?
The SI-defined ratios (e.g. 1 kWh = 3.6 MJ) are exact; a few (like horsepower and BTU) have standard rounded definitions used consistently here. Results are accurate for engineering, physics homework, and everyday use.