Force Calculator

How it works

1. 1Enter the object’s mass (kg or lb) and its acceleration (m/s² or ft/s²).
2. 2Both inputs are converted to SI base units (kg, m/s²) before the calculation.
3. 3Newton’s second law F = m·a is applied, and the result is shown in newtons, lbf, and kgf.

Use cases

• Engineering design — size actuators, fasteners, or structural members for a known load.
• Physics homework — solve dynamics problems involving net force and linear acceleration.
• Sports science — estimate the force a sprinter or vehicle must generate for a target acceleration.

Frequently asked questions

What formula does this calculator use?

It applies Newton’s second law of motion: F = m·a, where F is force in newtons, m is mass in kilograms, and a is acceleration in m/s². For example, a 10 kg object accelerating at 9.8 m/s² produces a force of 10 × 9.8 = 98 N.

What is the difference between newtons (N), lbf, and kgf?

Newtons (N) are the SI unit of force. Pound-force (lbf) is the imperial equivalent: 1 lbf ≈ 4.448 N. Kilogram-force (kgf) is the gravitational metric unit: 1 kgf = 9.80665 N, the weight of a 1 kg mass under standard gravity.

Can I use this to find weight?

Yes. Set the acceleration to the local gravitational acceleration — 9.8 m/s² on Earth’s surface. For example, a 70 kg person has a weight of 70 × 9.8 = 686 N (about 154 lbf or 70 kgf).