dopecalc

Force Calculator

Calculate force, mass, or acceleration from the other two values using Newton's second law: F = ma. Supports Newtons, dynes, and pound-force.

Enter any two of force, mass, or acceleration and leave the unknown blank. The calculator will solve for the missing value using F = m × a.

kg
m/s²

About this Calculator

Calculate force, mass, or acceleration from the other two values using Newton's second law: F = ma. Supports Newtons, dynes, and pound-force.

Formula & Calculations

Formula

F = m × a, m = F / a, a = F / m
Where:
  • F=Force — push or pull on an object
  • m=Mass — amount of matter
  • a=Acceleration — rate of change of velocity

Assumptions

  • Newton's second law applies: net force equals mass times acceleration.
  • Force, mass, and acceleration must be in consistent units.
  • Provide any two values to solve for the third.

Calculation Examples

Example 1

Inputs:Mass = 10 kg, Acceleration = 9.8 m/s²
Result:Force = 98 N

F = 10 × 9.8 = 98 N (weight of a 10 kg object on Earth).

Example 2

Inputs:Force = 500 N, Mass = 25 kg
Result:Acceleration = 20 m/s²

a = 500 / 25 = 20 m/s².

Example 3

Inputs:Force = 100 lbf, Acceleration = 32.174 ft/s²
Result:Mass = 3.108 slugs

m = F / a = 100 / 32.174 ≈ 3.11 slugs.

Frequently Asked Questions

What is a Newton?

One Newton (N) is the force required to accelerate a 1 kg mass at 1 m/s². It is named after Sir Isaac Newton and is the SI unit of force.

How are dynes and Newtons related?

A dyne is a CGS unit of force: 1 dyne = 0.00001 N. It takes 100,000 dynes to equal 1 Newton. Dynes are used for very small forces.

What is pound-force?

Pound-force (lbf) is the imperial unit of force, equal to the gravitational force on a 1 lb mass at Earth's surface. 1 lbf ≈ 4.448 N.