Grease Relubrication Interval Calculator

01 Bearing

Quick pick from lookup table Or type a designation directly

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Bearing type Bearing mass, M (kg) (optional — from catalog, needed for initial fill) Shaft orientation

02 Relubrication method

Grease type (for initial fill density) Very low speed, needs contaminant/corrosion protection (fill 70–100% instead)

03 Operating conditions

Rotational speed, n (rpm) Bearing operating temperature

Baseline is 70°C. Grease life is estimated to roughly halve for every 15°C above this, and roughly double for every 15°C below (within reasonable limits).

04 Environment & load

Contamination / environment Load ratio, C/P (basic dynamic load rating ÷ equivalent load)

At C/P ≥ 15, load doesn't significantly affect the interval. Below that, an SKF technical publication gives an explicit example: C/P=8 → a correction factor of 0.5. This tool linearly interpolates between C/P=15 (factor 1.0) and C/P=8 (factor 0.5), extrapolating cautiously below that.

MEAN DIAMETER dm

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SPEED FACTOR ndm

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BASE INTERVAL tf

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ADJUSTED RELUBRICATION INTERVAL

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Fill in the bearing, speed, and operating conditions to see the recommended interval.

CORRECTION FACTORS APPLIED

Bearing type–

Shaft orientation–

Temperature–

Contamination / environment–

Load–

GREASE QUANTITY (SKF METHOD)

Free volume, V–

Initial fill–

Replenishment shot, Gp–

Method: Grease quantities follow SKF's published method exactly: replenishment Gp = 0.005×D×B (relubricating from the side) or 0.002×D×B (through lubrication holes in the ring), and initial fill as 40% (side) or 20% (through-hole) of the bearing's free volume V = (π/4)·B·(D²−d²)×10⁻³ − M/(7.8×10⁻³) [cm³], converted to grease mass via density (≈0.9 g/cm³ standard grease, ≈2.0 g/cm³ fluorinated). For tapered roller bearings, use the overall width T in place of B (already handled automatically for tapered roller entries from the lookup table); for thrust bearings, use height H — not currently supported by this tool's lookup. The speed factor ndm = n × dm is a standard SKF convention. The base interval vs. speed‑factor curve uses piecewise interpolation directly across a 5‑point table (ndm 100,000–500,000) from a source citing the SKF General Catalogue relubrication diagram, and reproduces that source's own fully worked example to within 0.1%. An independent motor‑manufacturer lubrication table runs roughly 1.2–2.5× more conservative across most of this range — a genuine disagreement between two legitimate real‑world sources, not something this tool resolves; treat the output as one reasonable reference, not a universal number. Bearing‑type factors (ball/angular contact/self‑aligning = 1.0, cylindrical roller = 0.5, needle roller = 0.3, spherical or tapered roller = 0.2) and the vertical‑shaft factor (×0.5) are documented values from the same source. Temperature (halving per 15°C above 70°C) is independently verified — a computed 20°C‑rise multiplier of 0.40 matched a separately cited real‑world example almost exactly. Contamination factors are recalibrated within that source's cited ranges (clean=1.0, light=0.5–0.7, heavy=0.2–0.4). The load factor is now anchored to an explicit, named SKF correction (C/P=8 → 0.5, from SKF Engineering & Research Centre technical publication Lube‑Tech 044, 2006), linearly interpolated to the qualitative C/P≥15 threshold — a genuine sourced value rather than this tool's own guess, though still an interpolation between two points rather than SKF's full published curve. For warranty‑critical equipment or long‑interval automatic lubrication systems, verify against SKF's own calculation tool, the bearing manufacturer's chart, or a lubrication engineer.

© 2026 UNIQOL LTD. All rights reserved. This calculator, its formulas' implementation, bearing dimension tables, and design are original work and may not be copied, redistributed, or claimed as another party's work without permission.

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