Bearing Load Calculator
Computes the equivalent dynamic load on a bearing by combining radial and axial forces with an application load factor. Use this when selecting bearings or verifying load ratings in rotating machinery.
About this calculator
Bearings must withstand forces acting in two directions simultaneously: radial loads (perpendicular to the shaft axis) and axial loads (along the shaft axis). The resultant of these two orthogonal forces is found using the Pythagorean theorem: F_resultant = √(F_radial² + F_axial²). In real applications, shock, vibration, and mounting misalignment increase the effective load beyond this geometric resultant, so the result is multiplied by a dimensionless load factor (also called a service or application factor): F_equivalent = √(F_radial² + F_axial²) × load_factor. Load factors typically range from 1.0 (smooth, steady operation) to 3.0 or more (heavy shock loads). The equivalent load is then compared against the bearing's dynamic load rating C and desired service life to verify suitability. Bearing manufacturers such as SKF and NSK publish standard load factor tables for different machine types.
How to use
A shaft bearing experiences a radial load of 800 N and an axial load of 600 N, with a moderate shock load factor of 1.5. Step 1 – Calculate the geometric resultant: √(800² + 600²) = √(640,000 + 360,000) = √1,000,000 = 1,000 N. Step 2 – Apply the load factor: 1,000 × 1.5 = 1,500 N. Enter 800 in Radial Load, 600 in Axial Load, and 1.5 in Load Factor. The calculator returns an equivalent bearing load of 1,500 N, which you then compare to your chosen bearing's rated dynamic capacity.
Frequently asked questions
What is the difference between radial load and axial load on a bearing?
Radial load acts perpendicular to the shaft axis, like the weight of a gear or pulley pressing down on the shaft. Axial load (also called thrust load) acts parallel to the shaft axis, such as the force generated by helical gears or a propeller. Most rolling-element bearings can handle both types, but their relative magnitudes determine which bearing type — deep-groove ball, angular contact, or tapered roller — is most appropriate.
How do I choose the correct load factor for my bearing application?
Load factors are selected based on the operating conditions of the machine. A value of 1.0 applies to smooth, vibration-free operation such as precision instruments. Values of 1.2–1.5 suit normal electric motors and pumps with moderate shock. Heavy machinery with frequent shock loads, like crushers or hoists, requires factors of 2.0–3.0 or higher. Always consult the bearing manufacturer's application guidelines or ISO 281 for validated factors specific to your industry.
Why is the Pythagorean theorem used to combine radial and axial bearing loads?
Radial and axial forces act at right angles to each other in three-dimensional space, making them orthogonal vectors. The magnitude of the combined force vector is therefore the square root of the sum of their squares, exactly as the Pythagorean theorem describes for a right triangle's hypotenuse. This gives the true resultant force the bearing must resist, before any dynamic service factors are applied. Using simple addition would overestimate the load, while ignoring one component would dangerously underestimate it.