Force Converter

Force is any push or pull that can change the motion of an object. The newton is the SI unit, defined as the force needed to accelerate one kilogram by one metre per second squared.

This converter also handles pound-force, kilogram-force and dynes, which appear in engineering and physics work across different unit systems.

Several units on this page are defined as the weight of a mass at standard gravity rather than as a force in their own right. A kilogram-force is the force gravity exerts on one kilogram at 9.80665 m/s², which is exactly why its conversion factor to newtons is 9.80665: the factor is the acceleration.

Pound-force works the same way for the pound-mass, giving 4.4482216153 N. These units are convenient because they let you read a mass and a force off the same number, and they are avoided in physics for the same reason: the gravitational constant is baked in, so the arithmetic silently assumes Earth's surface.

• Kilogram-force is also written kilopond, and appears in older European engineering literature.
• The newton has no such assumption: it is defined from mass and acceleration directly, which is why SI calculations use it throughout.
• Mass belongs on the weight converter. This page is force, and mixing the two is the most common error in customary units.

US customary units have a long-standing awkwardness: the pound is used for both mass and force, so applying F = ma requires a conversion factor that SI does not need. Two different fixes were invented and both are still in circulation.

The poundal is the force that accelerates one pound-mass at one foot per second squared, making the equation work with the pound as a mass. Its ratio to pound-force is 32.174: the value of standard gravity in feet per second squared. The alternative fix keeps pound-force and introduces the slug as the unit of mass instead.

• Seeing 32.174 or 32.2 in an equation is usually a sign that a customary force-and-mass conversion is happening.
• The dyne is the CGS equivalent, at 10⁻⁵ N, and turns up in older physics and in surface-tension work.
• When a source mixes pounds without saying which kind, the units on the other quantities in the formula usually reveal it.