Mechanical

Bearing Load Calculator

Combine radial and axial bearing loads into equivalent dynamic and static loads, then check static safety factor.

Formula P = max(Fr, XFr + YFa)Reviewed Sep 8, 2026

Bearing catalogs do not rate every possible mix of radial and thrust load directly. They reduce the real load case to an equivalent dynamic bearing load P for fatigue-life checks and an equivalent static load P0 for brinelling or standstill checks. This bearing load calculator applies the catalog-factor method P = XFr + YFa and P0 = X0Fr + Y0Fa, reports the governing load, and shows whether the entered static rating clears your target safety factor.

Calculation Bench

Factor Preset

Presets fill common starting factors only. Replace them with the exact X/Y/X0/Y0 values from your bearing catalog before using the result.

01Radial Load

Fr · Load perpendicular to shaft axis

02Axial Load

Fa · Thrust load along shaft axis; leave blank for zero

03Dynamic Radial Factor

X · Catalog factor for P

04Dynamic Axial Factor

Y · Catalog thrust factor for P

05Static Radial Factor

X0 · Catalog factor for P0

06Static Axial Factor

Y0 · Catalog thrust factor for P0

07Dynamic Load Rating

C · Optional catalog C rating for P/C

08Static Load Rating

C0 · Optional catalog C0 rating for S0

09Target Static Safety

S0,target · Optional pass/fail threshold

Solution

Enter bearing loads and catalog factors to compute equivalent load and static safety.

P = max(Fr, XFr + YFa)

Formula Sheet

P=\max\left(F_r,\,X F_r+Y F_a\right)

P_0=\max\left(F_r,\,X_0F_r+Y_0F_a\right)

S_0=\dfrac{C_0}{P_0}

C_{0,req}=S_{0,target}P_0

FrRadial Load
FaAxial Load
XDynamic Radial Factor
YDynamic Axial Factor
PEquivalent Dynamic Load
X0Static Radial Factor
Y0Static Axial Factor
P0Equivalent Static Load
CDynamic Load Rating
C0Static Load Rating
S0Static Safety Factor

Starting Factor Presets - Replace with Catalog Values

Preset	Typical use	X	Y	X0	Y0	S0 target
Pure radial / pulley	Mostly radial load	1.00	0.00	1.00	0.00	1.5
Deep-groove hint	Combined radial + light thrust	0.56	1.60	0.60	0.50	1.5
Angular-contact hint	Higher thrust share	0.44	1.20	0.50	0.46	2.0
Tapered-roller hint	Heavy combined loading	0.40	1.50	0.50	0.40	2.0

Variables & Units

Symbol	Variable	Description	Common Units
Fr	Radial Load	Load acting perpendicular to the shaft or bearing axis.	N, kN, lbf
Fa	Axial Load	Thrust load acting parallel to the shaft or bearing axis.	N, kN, lbf
X	Dynamic Radial Factor	Catalog radial factor for equivalent dynamic load.
Y	Dynamic Axial Factor	Catalog axial factor for equivalent dynamic load.
P	Equivalent Dynamic Load	Single dynamic load used as the bearing fatigue-life input.	N, kN, lbf
X0	Static Radial Factor	Catalog radial factor for equivalent static load.
Y0	Static Axial Factor	Catalog axial factor for equivalent static load.
P0	Equivalent Static Load	Single static load used for static capacity and brinelling checks.	N, kN, lbf
C	Dynamic Load Rating	Catalog basic dynamic load rating for the bearing.	N, kN, lbf
C0	Static Load Rating	Catalog basic static load rating for the bearing.	N, kN, lbf
S0	Static Safety Factor	Ratio of static load rating to equivalent static load.

How to Use This Calculator

01Enter the radial load Fr acting perpendicular to the shaft and the axial or thrust load Fa acting along the shaft.
02Choose a preset only as a starting point, then replace X, Y, X0, and Y0 with the values from the exact bearing manufacturer's catalog.
03If the load comes from a pulley, gear, belt, or chain, first calculate the reaction at this bearing location rather than entering the total external load blindly.
04Optionally enter the bearing's basic dynamic rating C to see the P/C load ratio used before an L10 life check.
05Enter the basic static rating C0 and target static safety factor if you need a pass/fail standstill or shock-load screen.
06Use the required C0 result as a catalog-selection clue, not as final approval; lubrication, speed, fit, temperature, misalignment, and fatigue life still need separate checks.

How the Formula Works

The dynamic equivalent load P combines radial and axial load into one fatigue-load input. For a radial bearing this calculator does not let P fall below Fr, because a catalog factor combination should not reduce a pure radial load case below the radial load itself.

The static equivalent load P0 is computed with static catalog factors X0 and Y0, then also compared with Fr. Static safety factor is S0 = C0 / P0. If S0 is below the target, the bearing is not passing the simple static screen.

The vector resultant sqrt(Fr^2 + Fa^2) is shown for intuition, but it is not a replacement for ISO/catalog equivalent-load factors. Bearings respond differently to radial and thrust loading, so the catalog-factor result is the one to reuse in bearing-life calculations.

Worked Example 01

Pure radial bearing load screen

Known

Radial load: 5,000 N
Axial load: 1,500 N
Static factors: X0 = 0.6, Y0 = 0.5
Static rating: C0 = 20,000 N

Formula

S0 = C0 / P0

Substitution

P0 = max(5,000, 0.6 x 5,000 + 0.5 x 1,500) = 5,000 N; S0 = 20,000 / 5,000

Result

S0 = 4.0, so it passes a 1.5 target static-safety screen

The static factor combination is only 3,750 N, so the radial load governs. With C0 four times P0, this bearing has a large first-pass static margin.

Worked Example 02

Axial load controls the dynamic equivalent load

Known

Radial load: 8,000 N
Axial load: 3,000 N
Dynamic factors: X = 0.56, Y = 2.30

Formula

P = max(Fr, XFr + YFa)

Substitution

P = max(8,000, 0.56 x 8,000 + 2.30 x 3,000)

Result

P = 11,380 N

Even though the vector resultant is about 8.54 kN, the equivalent dynamic bearing load is 11.38 kN because the catalog axial factor makes thrust loading more damaging for this bearing case.

Applications

01Checking whether a bearing's static rating is adequate for a radial-plus-thrust load case
02Preparing equivalent dynamic load P before an L10 bearing-life calculation
03Comparing candidate bearings by P/C and C0/P0 screening ratios
04Teaching why vector resultant load is not the same as equivalent bearing load

Assumptions

01Radial and axial loads are the loads at the checked bearing, not just total shaft or gear-mesh force.
02Entered X, Y, X0, and Y0 factors match the exact bearing type, load ratio, contact angle, and catalog rule being used.
03The bearing is a rolling-element bearing where catalog equivalent-load methods are applicable.
04Loads are treated as steady values for a first-pass screen.

Where This Model Stops

01Does not automatically select ISO 281 X/Y/e factors; the preset values are learning shortcuts, not manufacturer catalog data.
02Does not calculate L10 life, reliability factors, lubrication factor, viscosity ratio, contamination factor, preload, fit, temperature, or minimum load.
03Does not account for variable-duty cycles, shock-load spectra, misalignment, housing stiffness, shaft deflection, or contamination severity.
04Does not split external shaft loads between two bearings; use a beam reaction or shaft-layout model first.
05Not a substitute for bearing manufacturer software, catalog limits, or an engineer's final machine-design review.

References

[1]
Equivalent Dynamic Load Calculator
NLHB Bearings
Reference for ISO-style P = XFr + YFa behavior and factor-table context.
[2]
Bearing Load Calculator
MachineCalcs
Cross-check reference for dynamic/static equivalent load, S0, and required C0 outputs.
[3]
Equivalent Dynamic Bearing Load
CalcExact
Reference for explaining why catalog factors differ from a vector resultant load.

Frequently Asked Questions

Where do X, Y, X0, and Y0 come from?

They come from the bearing manufacturer's catalog for the exact bearing family, load direction, contact angle, and Fa/Fr or Fa/C0 range. The presets here are only starting hints so users are not staring at blank factor fields.

Is equivalent bearing load the same as vector resultant load?

No. The vector resultant is sqrt(Fr^2 + Fa^2). Equivalent bearing load uses catalog factors because radial and axial loads affect rolling-element bearings differently. Use P or P0 for bearing rating checks, not the vector resultant alone.

How is this different from a shaft diameter calculator?

The Shaft Diameter Calculator sizes the shaft material from torque and allowable stress. This Bearing Load Calculator checks the load seen by a bearing and compares it with bearing catalog ratings. A real machine shaft often needs both checks.

Can this calculator select the final bearing size?

No. It gives a first-pass equivalent load and static safety screen. Final selection still needs L10 life, speed limits, lubrication, contamination, fit, temperature, preload, stiffness, misalignment, and manufacturer catalog rules.

Why does the calculator ask for bearing factors instead of choosing them automatically?

X, Y, X0, Y0, and e depend on the exact bearing series, contact angle, internal design, and load ratio. Generic auto-selection can look precise while using the wrong catalog row, so this page keeps the factors visible and editable.

Related Calculators