Engineering CalculatorsBearing Calculator
Propose a rolling-element or plain-bush bearing from a shaft diameter and combined radial/axial load — deep groove ball, angular contact ball, cylindrical/tapered/spherical/needle roller, thrust ball, or plain bush, sized to an ISO 281 target life (or, for a bush, a pressure-velocity limit), with sealed/grease/oil lubrication guidance and a cross-section diagram.
New to ISO 281? Read the guide: Bearing Life & Selection: How ISO 281 Rates a Rolling Bearing — a plain-language explainer of the standard behind this calculator.
Rolling-element bearings are sized by ISO 281 basic rating life, L10 = (C/P)^p million revolutions (p = 3 for ball bearings, 10/3 for roller bearings), converted to hours via L10h = 10⁶·L10 / (60·n). The candidate designation, envelope (d, D, B), dynamic rating C, static rating C0, fatigue load limit Pu, and limiting speed are taken from the real SKF "Rolling bearings" general catalogue (PUB BU/P1 17000/1 EN, 2018 edition) — the mainstream series of each type, extracted directly from the published product tables. From all catalogue bearings whose bore fits the shaft, the tool selects the smallest-capacity one that meets both the life and static-safety targets (so a light series is proposed where it suffices, stepping up to a medium/heavy series or larger bore only as the loads demand). The equivalent dynamic load P = X·Fr + Y·Fa uses the catalogue's own factor method: deep groove ball's e and Y vary with f0·Fa/C0 (SKF table 9, Normal clearance); angular contact uses the 25°/40° contact-angle factor set; spherical roller uses the double-row form (P = Fr + Y1·Fa below e); cylindrical and needle roller carry no axial load (P = Fr, and any entered axial load is flagged as unsupported); thrust ball carries axial load only (P = Fa). Where a family's e/Y vary per designation (tapered and spherical roller), a representative mainstream- series value is used, noted alongside the result. An optional duty/shock factor (1.0-2.5×) inflates the equivalent load before sizing, and the ISO 281:2007 reliability factor a1 (90-99%) adjusts the achieved life. Static adequacy is checked via s0 = C0 / P0 against a target that scales up for roller (line-contact) bearings. Lubrication guidance compares the speed factor n·dm against a representative grease/oil limit for the family and the catalogue limiting speed, plus the housing temperature against typical grease/seal service limits; the relubrication interval and viscosity band are rule-of-thumb estimates, not a substitute for the manufacturer's full lubrication- selection procedure. The shaft/housing temperature difference drives a qualitative internal- clearance advisory, not a quantitative clearance calculation. Plain bushes are sized by the pressure-velocity (PV) method against representative material limits, not a fatigue life. Bearing dimensions and ratings are ISO-standardised and stable across catalogue editions, but confirm the final designation against the current manufacturer datasheet, and have the complete arrangement (mounting, fits, internal clearance class, seals) reviewed before production use.
Validated: deep groove ball, shaft diameter 25 mm, radial load 2,000 N, axial load 0 N, speed 1,500 rpm, target life 4,000 h at 90% reliability, steady duty, normal static duty (all other defaults) returns the real catalogue bearing 6205 — SKF-published C = 14.8 kN, C0 = 7.8 kN, d 25 / D 52 / B 15 mm. By hand: since Fa = 0, X = 1 and Y = 0, so P = Fr = 2,000 N. L10 = (14,800/2,000)³ = 405.2 million revolutions, so L10h = 10⁶ × 405.2 / (60 × 1,500) = 4,502 h — above the 4,000 h target. Static side: P0 = max(0.6×2,000, 2,000) = 2,000 N, required C0 = 1.5 × 2,000 = 3,000 N against the catalogue C0 of 7,800 N (s0 = 3.9). This calculator returns exactly these figures, and the 6205 dimensions and ratings match the SKF catalogue product table entry directly.