Bearing Life Calculator (L10)
ISO 281 basic rating life for single-row deep groove ball bearings — pick a bearing from the built-in catalogue or enter your own C/C0, add the radial and axial load, and get L10, L10h, a reliability-adjusted life and a static safety check, live.
Bearings fail from rolling-contact fatigue, not from a single overload — so "life" here is statistical, not a hard number. The chart below is the single most useful thing to internalise about it: because life scales with the cube of the load, small changes in load swing life by a lot more than you'd expect. Halving the load doesn't double the life — it multiplies it by eight.
Basic rating life — ISO 281
Ball bearings, load-life exponent p = 3.
Life sensitivity to load
Guidance only. This covers the basic ISO 281 rating life (L10) and the reliability factor a1 for single-row deep groove ball bearings — it does not include lubrication/contamination effects, fatigue-limit load, or any check specific to other bearing types. For a safety-critical or highly loaded application, verify against the bearing manufacturer's full selection method. See the FAQ below.
How the numbers are calculated
Equivalent dynamic load P
If Fa/Fr > e: P = 0.56·Fr + Y·Fa
e and Y aren't fixed — they depend on Fa/C0 for the specific bearing, interpolated from the standard single-row deep groove ball bearing table (e ranges roughly 0.19-0.44, Y from 2.3 down to 1.0 as Fa/C0 grows). The calculator reads C0 from whichever bearing you've selected and interpolates live — the readout above the results shows exactly which branch applied and why.
Basic rating life
L10h = L10 · 1,000,000 / (60 · n)
The exponent 3 is specific to ball bearings (roller bearings use 10/3, not covered here). Because it's a cube, the load-sensitivity chart above is the real story: reducing the equivalent load by a modest amount buys disproportionately more life.
Reliability-adjusted life
a1 = 1 at the baseline 90% reliability (L10 itself). Choosing a higher reliability multiplies by a smaller a1 (down to 0.21 at 99%) — see the FAQ for why that drop isn't linear.
Static safety factor
s0 = C0 / P0
A separate check from L10 — see the FAQ for when it's the one that actually matters.
Bearing catalogue reference
Single-row deep groove ball bearings, 60/62/63 series. Click a row to load it into the calculator above.
| Designation | Series | d [mm] | D [mm] | B [mm] | C [kN] | C0 [kN] |
|---|---|---|---|---|---|---|
| 6001 | Extra light (60) | 12 | 28 | 8 | 5.07 | 2.36 |
| 6002 | Extra light (60) | 15 | 32 | 9 | 5.59 | 2.85 |
| 6003 | Extra light (60) | 17 | 35 | 10 | 6.05 | 3.25 |
| 6004 | Extra light (60) | 20 | 42 | 12 | 9.36 | 5 |
| 6005 | Extra light (60) | 25 | 47 | 12 | 11.2 | 6.55 |
| 6006 | Extra light (60) | 30 | 55 | 13 | 13.3 | 8.3 |
| 6007 | Extra light (60) | 35 | 62 | 14 | 15.9 | 10.2 |
| 6008 | Extra light (60) | 40 | 68 | 15 | 16.8 | 11.6 |
| 6201 | Light (62) | 12 | 32 | 10 | 6.89 | 3.1 |
| 6202 | Light (62) | 15 | 35 | 11 | 7.8 | 3.75 |
| 6203 | Light (62) | 17 | 40 | 12 | 9.56 | 4.75 |
| 6204 | Light (62) | 20 | 47 | 14 | 12.7 | 6.55 |
| 6205 | Light (62) | 25 | 52 | 15 | 14 | 7.8 |
| 6206 | Light (62) | 30 | 62 | 16 | 19.5 | 11.2 |
| 6207 | Light (62) | 35 | 72 | 17 | 25.5 | 15.3 |
| 6208 | Light (62) | 40 | 80 | 18 | 30.7 | 19 |
| 6301 | Medium (63) | 12 | 37 | 12 | 9.75 | 4.15 |
| 6302 | Medium (63) | 15 | 42 | 13 | 11.4 | 5.4 |
| 6303 | Medium (63) | 17 | 47 | 14 | 13.5 | 6.55 |
| 6304 | Medium (63) | 20 | 52 | 15 | 15.9 | 7.8 |
| 6305 | Medium (63) | 25 | 62 | 17 | 22.5 | 11.6 |
| 6306 | Medium (63) | 30 | 72 | 19 | 28.1 | 16 |
| 6307 | Medium (63) | 35 | 80 | 21 | 33.2 | 19 |
| 6308 | Medium (63) | 40 | 90 | 23 | 41 | 24 |
Glossary
- C (basic dynamic load rating)
- The constant radial load a bearing can theoretically endure for a rating life of exactly 1 million revolutions — a fixed property of the bearing's size and internal design, not of your application.
- C0 (basic static load rating)
- The static load that produces a defined small permanent deformation (about 0.0001 of the rolling element diameter) at the most heavily loaded contact point — used for the static safety factor, not for fatigue life.
- P (equivalent dynamic load)
- A single constant radial load that would give the same fatigue life as the actual combination of radial and axial load the bearing really sees.
- X, Y, e
- X and Y weight the radial and axial load inside the P formula; e is the Fa/Fr threshold below which the axial component is small enough to ignore. All three come from a standard table indexed by Fa/C0.
- L10 / L10h
- Basic rating life at 90% reliability, in millions of revolutions (L10) or operating hours at a given speed (L10h).
- a1 (reliability factor)
- Multiplier applied to L10 to get the life at a reliability other than 90% — always ≤1 for reliability >90%, since asking for fewer failures means accepting a shorter guaranteed life.
- P0, s0 (static load and safety factor)
- P0 is the equivalent static load; s0 = C0/P0 checks against permanent indentation rather than fatigue.
Frequently asked questions
What is L10 life?
L10 is the basic rating life defined by ISO 281: the number of revolutions (or hours, at a given speed) that 90% of a sufficiently large group of apparently identical bearings, running under the same load, can be expected to reach or exceed before the first sign of fatigue (spalling/flaking on a raceway). For a single bearing, L10 is also the life at which there is a 90% chance of not seeing that failure — the other 10% is the accepted statistical risk baked into the standard.
What's the difference between L10 and L10h?
L10 is expressed in millions of revolutions — a pure geometry/load number, independent of how fast the bearing turns. L10h converts that into operating hours at a specific rotational speed: L10h = L10 · 1,000,000 / (60 · n). Two applications with the same L10 can have very different L10h if one spins much faster than the other.
Why does axial load matter so much even when it looks small next to the radial load?
Deep groove ball bearings carry radial and axial load very differently internally, so you can't just add Fr and Fa together. The equivalent dynamic load P = X·Fr + Y·Fa reflects that: Y (the axial weighting factor) is often larger than 1, sometimes over 2, particularly at low Fa/C0 ratios — so a modest axial load can contribute as much fatigue damage as a much larger radial one. Below a threshold ratio (Fa/Fr ≤ e) the axial component is small enough to ignore and P = Fr; above it, the combined formula kicks in and e itself gets smaller as the axial share of load grows, which is precisely why the calculator interpolates it live instead of using one fixed value.
Why does going from 90% to 99% reliability cost so much life?
The a1 factor isn't linear: at 95% reliability the modified life is 62% of L10, at 99% it drops to just 21% — less than a quarter. This reflects the shape of the underlying fatigue-life distribution (a Weibull distribution, steep in its early-failure tail): pushing the acceptable failure rate down from 1-in-10 to 1-in-100 bearings means designing for a point much further out on that steep part of the curve. It's the same logic as extreme weather return periods — halving the chance of an event doesn't just double the timescale you have to plan for.
What is the static safety factor s0, and when does it matter more than L10?
L10 assumes the bearing is rotating under load. s0 = C0/P0 checks something different: whether a load — rotating or not — would leave a permanent dent (brinelling) in the raceway, using the equivalent static load P0 = 0.6·Fr + 0.5·Fa (never less than Fr). This matters most for loads applied while stationary or barely moving (shock loads, occasional peak loads, a crane hook at rest under full load) — cases where fatigue life isn't the limiting factor at all, but a single overload event could still ruin the bearing. As a rule of thumb from bearing manufacturers' literature: s0 below ~1 leaves little margin, 1-2 is normal for typical machinery, and above ~2 is the range usually recommended for shock loads or high running-smoothness requirements.
Why isn't lubrication/contamination (the aISO or aSKF factor) included?
The full ISO 281:2007 method adds a third modification factor for lubrication film thickness (viscosity ratio κ) and contamination level, which under good conditions can multiply the basic L10 several times over — but it needs inputs this calculator deliberately doesn't ask for (actual operating viscosity, oil cleanliness class, etc.) and is easy to misuse without understanding the underlying model. This first version sticks to the basic rating life L10 plus the reliability factor a1, both of which only need data you already have. A full aISO/aSKF calculator is a natural next step if there's demand for it.
Where do I get C and C0 for my actual bearing?
The built-in catalogue below covers common single-row deep groove ball bearings (60/62/63 series) with typical dynamic (C) and static (C0) load ratings, useful for estimating and learning. For a real design, always confirm against the datasheet of the specific bearing you intend to buy — C and C0 can vary a few percent between manufacturers even for identical bore/OD/width, and switching to a different bearing type (angular contact, roller, etc.) needs its own X/Y/e table and load-life exponent, which this calculator doesn't cover.
References & further reading
- ISO 281:2007 — Rolling bearings, dynamic load ratings and rating life — the standard behind the L10 basic rating life formula used in this calculator.
- Bearing rating life — SKF Group — a major bearing manufacturer's own explanation of L10 and modified rating life.
- Load ratings and bearing life — NHBB Engineering Reference — worked equations and life-adjustment factors, cross-checked against ANSI/ABMA 9.
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