Introduction / overview

Force Converter turns one force value into equivalent values across the units engineers, physicists, and hobbyists actually reach for — newtons, kilonewtons, dynes, pounds-force, grams-force, kilograms-force, and metric tonnes-force, plus a set of extra units such as millinewtons, poundals, kips, and kiloponds.

Enter a value in any field, and the equivalent force is recalculated across every unit at once. You can start from the unit you have and read the unit you need, in either direction.

It is the kind of tool you reach for when a datasheet lists a force in kilonewtons but your torque wrench or test spec expects pounds-force, or when a physics problem states a force in dynes and you need newtons. The fixed fields cover the common units, and the additional field covers less frequent units like poundals, kips, sthènes, and kiloponds.

How to use / quick start

1Find the field for the unit you already know, and enter the force value there.
2Read the equivalent value in the unit you need. Every other field represents the same force, so nothing else has to be typed.
3If the unit you need is not one of the fixed fields, select it in the extra field — millinewtons, dekanewtons, meganewtons, giganewtons, teranewtons, poundals, kips, sthènes, or kiloponds.

Example: converting 700 newtons to pounds-force

Type $700$ in the Newtons field. The calculator divides by the exact pound-force factor declared for this tool:

700\ \mathrm{N}

\times

\frac{1\ \mathrm{lbf}}{4.4482216152605\ \mathrm{N}}

=

157.366\ \mathrm{lbf}

The same force is shown at the same time as $0.7\ \mathrm{kN}$ , $71.38\ \mathrm{kgf}$ , and $700{,}000\ \mathrm{mN}$ , so you can read every unit you need in one pass.

Calculation method

Internally, every field is converted through newtons. If $F_s$ is the value you entered and $f_s$ is the number of newtons in one source unit, the shared force is:

F_{\mathrm{N}} = F_s \times f_s

F_t

=

F_{\mathrm{N}} \div f_t

=

F_s \times f_s \div f_t

How to read the method:

$F_{\mathrm{N}}$ is the shared force expressed in newtons.
$f_s$ and $f_t$ are the declared newtons-per-unit factors for the source and target units, such as $4.4482216152605\ \mathrm{N/lbf}$ or $9.80665\ \mathrm{N/kgf}$ .
You can enter any editable field, so the same relationship works in both directions rather than only from newtons outward.

Force vs. mass and unit families

The newton: the SI unit of force

The newton is a derived SI unit built from the base units metre, kilogram, and second. From Newton's second law, one newton is the force needed to accelerate one kilogram at one metre per second squared:

1\ \mathrm{N}

=

1\ \mathrm{kg \cdot m/s^2}

To get a feel for the scale: on the surface of the Earth, a 1 kg mass weighs about $9.81\ \mathrm{N}$ , and a typical apple weighs close to $1\ \mathrm{N}$ .

Force is not mass

Kilograms and pounds are mass; newtons and pounds-force are force. A kilogram-force is not a kilogram — it is the force Earth's standard gravity exerts on a 1 kg mass. That is why this converter carries the $\mathrm{kgf}$ and $\mathrm{lbf}$ units, and why a value typed there is a force, not a mass.

If what you actually have is a mass in kilograms or pounds, use the Weight Converter to convert between mass units instead of entering it here.

Why some units are exact

The gravity-based units — grams-force, kilograms-force, kiloponds, pounds-force, kips, and metric tonnes-force — are defined against the standard reference acceleration of gravity, $9.80665\ \mathrm{m/s^2}$ , which this calculator uses. That makes $1\ \mathrm{kgf} = 9.80665\ \mathrm{N}$ and $1\ \mathrm{lbf} = 4.4482216152605\ \mathrm{N}$ exact rather than approximate. Purely kinematic units such as the dyne ( $0.00001\ \mathrm{N}$ ) and the poundal ( $0.138254954376\ \mathrm{N}$ ) are defined directly from mass and acceleration instead.

Easy-to-miss unit traps

$\mathrm{kip} = 1000\ \mathrm{lbf}$ — a kip is a force, not a kilogram or a kilopound of mass.
The poundal is a different unit from the pound-force: it is defined by the foot–pound–second system, about $0.138\ \mathrm{N}$ , not $4.448\ \mathrm{N}$ .
Kilopond ( $\mathrm{kp}$ ) and kilogram-force ( $\mathrm{kgf}$ ) are the same force, so both read $9.80665\ \mathrm{N}$ here.

If you have a force and a mass and want the acceleration it produces, the Magnitude of Acceleration Calculator solves $a = F/m$ for you.

Force Converter

Introduction / overview

How to use / quick start

Calculation method

Limitations

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