Normal Force Calculator
Calculate normal force on flat and inclined surfaces using F_n = mg cos(θ). See the parallel component that drives sliding.
NORMAL FORCE
490.3325 N
WEIGHT
490.3325 N
PARALLEL FORCE
0 N
FORMULA
Fn = mg cos(θ)
💡 How to Calculate Normal Force
What Is Normal Force?
Normal force is the perpendicular contact force exerted by a surface on an object resting on it. It is called "normal" because it acts perpendicular (at a right angle) to the surface. The normal force prevents objects from passing through surfaces.
On a flat surface, the normal force equals the object's weight. On an inclined surface, the normal force is less than the weight because a component of gravity acts along the slope.
How to Calculate Normal Force
Normal Force Formula
Where:
- F_n = normal force (N)
- m = mass (kg)
- g = 9.81 m/s²
- θ = angle of incline (degrees)
On a flat surface (θ = 0°): cos(0°) = 1, so F_n = mg (the full weight).
On a 30° incline: F_n = mg × cos(30°) = 0.866 × mg — about 86.6% of the weight.
Normal Force and Friction
Normal force directly affects friction. Since friction F_f = μ × F_n, a lower normal force (such as on a steeper incline) means less friction. This is why objects are more likely to slide on steeper slopes. Use our coefficient of friction calculator to find μ from the forces involved.