EngineeringFormulaForce (F)
Force is a push or pull on an object, causing it to accelerate, deform, or change momentum.
Newton's second law, F = ma, is the base relationship; most force calculations on this site either apply it directly or rearrange a related law (gravitation, buoyancy, stress) that has force as one term. Base SI unit is the newton (N); US customary work commonly uses pound-force (lbf).
A common mix-up in US customary units: pound-force (lbf, a unit of force) and pound-mass (lbm, a unit of mass) are both casually called "pounds," but they aren't interchangeable in a calculation - a 1 lbm object weighs 1 lbf only at standard Earth gravity. This site's Force calculator works entirely in mass and force as separate, explicit units to avoid that ambiguity.
Typical Forces by Context
| Context | Force (N) | Force (lbf) |
|---|---|---|
| Weight of a 1 kg mass at Earth gravity | 9.81 | 2.2 |
| Adult human body weight (~75 kg) | 736 | 165 |
| Weight of a small car (~1,200 kg) | 11,772 | 2,647 |
| Maximum human hand grip force | ~400–500 | ~90–112 |
Used In These Calculators
Frequently Asked Questions
What's the difference between force and pressure?
Force is a total push or pull; pressure is that force divided by the area it's spread over (p = F/A). The same force concentrated on a small area produces much higher pressure than spread over a large one - which is why a needle penetrates skin under far less total force than a blunt object.
Is weight the same thing as mass?
No, though they're proportional on Earth's surface, which is why they're often confused. Mass (kg) is an intrinsic property of an object - how much matter it has. Weight is the gravitational force on that mass (W = mg), which changes with gravity: the same object weighs about one-sixth as much on the Moon, but its mass is unchanged.
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