What is the bearing static safety factor s0?

The static safety factor s0 is the ratio of the basic static load rating C0 to the actual static equivalent load P0. It ensures the bearing does not suffer permanent deformation under static or shock loads. s0 = C0 / P0.

What is the minimum recommended s0 value?

Minimum s0 depends on the application: s0 ≥ 1.0 for normal quiet operation with ball bearings, s0 ≥ 1.5 for roller bearings under normal loads, s0 ≥ 2.0 for shock loads or vibrating equipment, and s0 ≥ 3.0 for high reliability or safety-critical applications.

What happens if s0 is too low?

If s0 is below the recommended minimum, the bearing may develop permanent indentations (brinelling) in the raceways. This leads to increased noise, vibration, and premature fatigue failure.

How do I determine the static equivalent load P0?

For radial bearings: P0 = X0·Fr + Y0·Fa, or P0 = Fr (whichever is larger). For thrust bearings: P0 = Fa + 2.3·Fr·tan(α). The factors X0 and Y0 depend on the bearing type.

Does s0 apply to rotating bearings?

s0 is primarily for static or very slow rotation conditions (n < 10 RPM), or for shock/impact loads during operation. For normal rotating conditions, the dynamic load rating C and fatigue life L10 are used instead.

Free Engineering Tool #045

Bearing Static Safety Factor Calculator

Calculate the static safety factor s₀ = C₀ / P₀ per ISO 76. Check if your bearing meets minimum safety factor requirements.

ISO 76 s₀ = C₀/P₀ Safety Assessment

Basic Static Load Rating C₀ (kN)

Static Equivalent Load P₀ (kN)

Application Type

Bearing Type

Quick presets

Results

Static Safety Factor s₀

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Minimum Required s₀

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Assessment

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Safety Margin

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Static Safety Factor

Per ISO 76, the static safety factor is the ratio of the basic static load rating to the actual static equivalent load:

C₀ — basic static load rating (kN), from bearing catalog
P₀ — static equivalent load (kN), calculated from actual radial & axial forces

Minimum s₀ Recommendations

Application	Ball Bearings	Roller Bearings
Low noise / smooth running	≥ 2.0	≥ 3.0
Normal quiet operation	≥ 1.0	≥ 1.5
Vibrating / shock loads	≥ 1.5	≥ 2.0
High reliability / safety	≥ 2.0	≥ 3.0
Light load, hand rotation	≥ 0.5	≥ 1.0

Practical Example

Example — 6208 Deep Groove Ball Bearing

Given: C₀ = 31.5 kN, P₀ = 12 kN, normal operation

s₀ = 31.5 / 12 = 2.63

Minimum required: s₀ ≥ 1.0 → PASS (margin +163%)

ℹ️ Tip: For bearings subjected to shock loads during operation (e.g., jaw crushers, vibrating screens), always check s₀ in addition to the dynamic life calculation.

Bearing Static Safety Factor Calculator | ISO 76 | Free Online Tool

Published by admin on February 15, 2026 February 15, 2026

Results

Static Safety Factor

Minimum s0 Recommendations

Practical Example

Minimum s₀ Recommendations