Force Calculator (F=ma)
Find the net force on an object from its mass and acceleration using Newton's second law.
kg
m/s²
- 1
Newton's second law
F = 10 kg × 9.81 m/s² = 98.10F = m × a with SI inputs gives force directly in newtons. - 2
Force in kilonewtons
98.10 ÷ 1,000 = 0.0981
Formula
How this is calculated
The calculator takes two inputs: the object's mass, in kilograms (kg), and its acceleration, in metres per second squared (m/s²). Mass measures how much matter an object contains and how strongly it resists changes in motion; acceleration is how quickly its velocity is changing.
It then applies Newton's second law directly: it multiplies mass by acceleration to give the net force, F = m × a. Because the inputs are in SI units, the result is the force in newtons (N) — one newton being the force that accelerates a 1 kg mass at 1 m/s². The result is also shown in kilonewtons (force ÷ 1000) and in kilogram-force (force ÷ 9.80665, the standard gravity value), purely as unit conversions of the same quantity.
This is the net (resultant) force — the single combined effect of all forces acting on the body. It assumes a constant mass and a rigid object, and ignores friction, air resistance, and relativistic effects, which only matter at speeds near that of light. A negative acceleration simply yields a force in the opposite direction.
Examples
| Input | Result |
|---|---|
| m = 10 kg, a = 9.81 m/s² | F = 98.1 N |
About this calculator
Newton's second law of motion states that the net force acting on an object equals its mass multiplied by its acceleration (F = m × a). Force is measured in newtons (N), where one newton is the force needed to accelerate a one-kilogram mass at one metre per second squared.
This relationship is fundamental to classical mechanics. A larger mass requires more force to achieve the same acceleration, and for a fixed force, a heavier object accelerates more slowly. Be sure to use SI units — kilograms for mass and metres per second squared for acceleration — to obtain force directly in newtons.
Frequently asked questions
Force equals mass times acceleration: F = m × a. With mass in kilograms and acceleration in m/s², force comes out in newtons.
One newton (1 N) is the force required to accelerate a mass of one kilogram at one metre per second squared.
Divide the force in newtons by 9.80665. For example, 98.1 N ÷ 9.80665 ≈ 10 kgf.
Also known as
TG we-Calculate Editorial Team. (2026). Force Calculator (F=ma) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/force-calculator
TG we-Calculate Editorial Team. "Force Calculator (F=ma)." TG we-Calculate. 2026. https://we-calculate.com/calculator/force-calculator.
TG we-Calculate Editorial Team, "Force Calculator (F=ma)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/force-calculator
@misc{wecalculate_force_calculator, title = {Force Calculator (F=ma)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/force-calculator}}, year = {2026}, note = {TG we-Calculate} }
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