Force Calculator
Calculate force, mass, or acceleration using Newton's Second Law F = ma. Supports Newtons, pounds-force, and kilogram-force.
kg
m/s²
N
Force (Newtons)
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Force (lbf) —
Force (kgf) —
Mass (kg) —
Acceleration (m/s²) —
How to Use This Calculator
- Select what to solve for: Force, Mass, or Acceleration.
- Enter the two known values.
- Results show the answer in Newtons, pounds-force, and kilogram-force.
Formula
F = m × a | m = F ÷ a | a = F ÷ m
where F = Newtons (N), m = kilograms (kg), a = m/s²
Example
Example: m = 70 kg, a = 9.81 m/s² (gravity) → F = 686.7 N = 154.4 lbf (weight of a 70 kg person).
Frequently Asked Questions
- Newton's Second Law states that Force = Mass × Acceleration (F = ma). Force is measured in Newtons (N), mass in kilograms (kg), and acceleration in m/s².
- 1 Newton is the force required to accelerate a 1 kg mass at 1 m/s². It equals approximately 0.2248 pounds-force.
- Standard gravity is 9.80665 m/s² (g). The weight of a 70 kg person is 70 × 9.81 = 686.7 N.
- Weight = Mass × g = Mass × 9.80665 m/s². Enter the mass and set acceleration to 9.80665 to calculate weight in Newtons.
- Mass is the amount of matter in an object (kg) and does not change. Weight is the gravitational force on that mass (N) and varies with gravity.