Bearing Load Calculator

Calculate bearing dynamic equivalent load, fatigue life, and static safety factor from radial and axial loads, ratings, speed, and bearing type.

Enter bearing data, then click Calculate.

Dynamic Load

Fatigue Life

Static Load

Bearing type Radial load Fr

Axial load Fa

Dynamic radial factor X, optional Dynamic axial factor Y, optional Output unit

Show Calculation Steps ▼

Bearing Load Formula

The bearing load calculator uses separate formulas for dynamic equivalent load, fatigue life, and static load. Loads are internally converted to newtons before calculation, then converted back to the output unit you select.

Dynamic equivalent bearing load

P = X \cdot F_r + Y \cdot F_a

P = equivalent dynamic bearing load
F_r = radial load on the bearing
F_a = axial load on the bearing
X = dynamic radial load factor
Y = dynamic axial load factor

Bearing fatigue life

L_{10} = \left({C \over P}\right)^p

L_{na} = L_{10} \cdot a_1 \cdot a_{ISO}

Life_{hours} = {L_{na} \cdot 1000000 \over 60 \cdot n}

C_{required} = P \cdot \left({t \cdot 60 \cdot n \over 1000000 \cdot a_1 \cdot a_{ISO}}\right)^{1/p}

L₁₀ = basic rating life in millions of revolutions
L_na = adjusted rating life in millions of revolutions
C = basic dynamic load rating
P = equivalent dynamic bearing load
p = life exponent, 3 for ball bearings or 10/3 for roller bearings
a₁ = reliability factor
a_ISO = lubrication or environment factor
n = rotational speed in rpm
t = target life in hours
C_required = dynamic load rating needed to meet the target life

Static equivalent bearing load

P_0 = max(F_r,\ X_0 \cdot F_r + Y_0 \cdot F_a)

s_0 = {C_0 \over P_0}

C_{0,required} = s_{0,target} \cdot P_0

P₀ = static equivalent bearing load
C₀ = basic static load rating
X₀ = static radial load factor
Y₀ = static axial load factor
s₀ = static safety factor
s_0,target = target static safety factor
C_0,required = static load rating needed for the selected safety factor

The dynamic load function calculates the single equivalent load used for fatigue life checks. The fatigue life function uses a known or estimated equivalent dynamic load to estimate bearing life in revolutions and hours. The static load function checks whether the bearing has enough static capacity for the applied radial and axial loads.

Bearing Factors and Load Rating Reference

The calculator can estimate bearing factors by bearing type, or you can enter custom X, Y, X₀, and Y₀ values from a bearing catalog.

Bearing type	Dynamic factor rule used	Estimated X	Estimated Y
Deep groove ball	If F_a/F_r ≤ 0.30, radial dominant. Otherwise combined load.	1.00 or 0.56	0.00 or 1.63
Angular contact ball	If F_a/F_r ≤ 0.68, radial dominant. Otherwise combined load.	1.00 or 0.44	0.00 or 1.17
Cylindrical roller	Estimated combined load factors	1.00	0.50
Spherical roller	If F_a/F_r ≤ 0.25, radial dominant. Otherwise combined load.	1.00 or 0.67	0.00 or 2.00
Tapered roller	If F_a/F_r ≤ 0.35, radial dominant. Otherwise combined load.	1.00 or 0.40	0.00 or 1.60
Thrust bearing	Load based on axial load	0.00	1.00

Input or selection	Value used	How to interpret it
90 percent reliability	a₁ = 1.00	Base L₁₀ rating life
95 percent reliability	a₁ = 0.62	Reduces adjusted life for higher reliability
99 percent reliability	a₁ = 0.21	Much shorter adjusted life than the base rating
Smooth running static target	s₀ = 1.0	Lower static margin
Normal service static target	s₀ = 1.5	Common general-purpose margin
Shock or vibration static target	s₀ = 2.0 to 3.0	Use a higher margin when peak loads are likely

Example Bearing Load Calculations

Example 1: Dynamic equivalent load for a deep groove ball bearing

You have a deep groove ball bearing with a radial load of 2,000 N and an axial load of 800 N.

{F_a \over F_r} = {800 \over 2000} = 0.40

Because 0.40 is greater than 0.30, the calculator uses the estimated deep groove combined-load factors X = 0.56 and Y = 1.63.

P = 0.56 \cdot 2000 + 1.63 \cdot 800 = 2424\ N

The equivalent dynamic bearing load is 2,424 N.

Example 2: Fatigue life from C and P

You have a ball bearing with C = 25 kN, P = 2.5 kN, speed = 1,200 rpm, reliability factor a₁ = 1.00, and lubrication factor = 1.00.

L_{10} = \left({25000 \over 2500}\right)^3 = 1000

The basic rating life is 1,000 million revolutions.

Life_{hours} = {1000 \cdot 1000000 \over 60 \cdot 1200} = 13888.9\ hours

The adjusted life is about 13,889 hours when a₁ and the lubrication factor are both 1.00.

Bearing Load Calculator FAQ

What is equivalent bearing load?

Equivalent bearing load is a single calculated load that represents the combined effect of radial and axial loading. It lets you compare a real loading condition against a bearing load rating. For dynamic checks, the calculator reports P. For static checks, it reports P₀.

Should you enter catalog X and Y factors?

Use catalog factors when you have them. The built-in factors are estimates based on bearing type and load ratio. Bearing catalogs may give different factors depending on contact angle, internal geometry, bearing arrangement, and the ratio of axial load to radial load.

Why does bearing life change so much when load changes?

Bearing fatigue life is based on the load ratio raised to a power. For ball bearings, life is proportional to (C/P)³. For roller bearings, life is proportional to (C/P)^10/3. Because of that exponent, a small increase in equivalent load can cause a large decrease in calculated life.