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F = m × a, W = m × g

Force calculator

Leave one field empty. The page solves F = ma and reports the weight of the same mass under standard gravity, so the two are never confused.

Short answer: 10 kg accelerated at 2 m/s² needs 20 N. The same 10 kg weighs 98.07 N standing still, because gravity supplies 9.80665 m/s² of acceleration.

Force, weight and where each is used

A newton is the force that gives one kilogram an acceleration of one metre per second squared. Weight is just the special case where the acceleration is gravity, which is why the two share a formula and never a number.

Worked example

A 1,200 kg car braking at 6 m/s²: the braking force is 1,200 × 6 = 7,200 N. Its weight is 11,768 N, so the tyres must deliver roughly 61% of the car's weight as friction to achieve that deceleration.

Force questions

What is the formula for force?

F = ma — force equals mass times acceleration, in newtons when mass is in kilograms and acceleration in metres per second squared. A 10 kg mass accelerated at 2 m/s² needs 20 N.

How is weight different from mass?

Mass is the amount of matter in kilograms and does not change; weight is the force gravity exerts on it, W = mg, and changes with location. The same 10 kg weighs 98.07 N on Earth and 16.6 N on the Moon.

Why does the page also show weight?

Because "force" and "weight" are routinely confused in homework and in kitchens. Both are labelled with their formula so the newton figure you get is the one you actually meant.

What is standard gravity?

9.80665 m/s², the internationally agreed average at sea level. It varies by about 0.5% between the equator and the poles, so weight calculated here is the standard-gravity figure.

Related tools

Kinetic and potential energy calculatorWhat that force does over a distance.Density calculatorMass from volume and density.Ohm's law calculatorThe same two-known-values pattern in circuits.