💪Force Calculator

About this tool

Choose whether to solve for force, mass or acceleration, and enter the other two in any units. In the second section, list forces with their angles to get the resultant's size and direction.

Newton's second law and vector forces

F = m × a: the net force on an object equals its mass times its acceleration, with force in newtons (1 N gives 1 kg an acceleration of 1 m/s²). A 1,500 kg car accelerating at 3 m/s² needs a net force of 4,500 N (about 1,012 lbf); the same force would accelerate a 3,000 kg van at only 1.5 m/s². Rearranged, m = F ÷ a and a = F ÷ m. The tool converts kN, pound-force, kilogram-force and dynes, and pounds, grams and tonnes. Forces are vectors with direction as well as size, so several forces are added by resolving each into x and y components (F cos θ and F sin θ), summing them, and recombining. Two 10 N forces at right angles give a 14.14 N resultant at 45°. If the resultant is zero, the forces are balanced and the object stays still or keeps moving steadily. Honest limits: use the net force, after friction and drag, in F = ma; angles are measured anticlockwise from the positive x axis. The momentum calculator and the inclined plane calculator are related.

Frequently asked questions