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Bearing Part Number Decoder

Decode SKF, FAG, Timken, NSK, NTN, and Koyo bearing designations. Get boundary dimensions, suffix meanings, deep-groove-ball clearance values from ISO 5753-1, cross-vendor equivalents, and prefill links to the six ToolGrit bearing calculators.

A six-manufacturer rolling-bearing decoder for plant maintenance, motor shops, gearbox service, and reliability engineers. Type or paste a bearing part number (e.g. 6205-2RS1/C3, NU310, NSK 6308DDU, FAG 22210-E1-K, Fafnir 205PP) and the tool resolves the basic designation against ISO 15 boundary dimensions, walks every suffix token against the maker-specific dictionary, normalizes closure (seal / shield) and clearance intents into a cross-vendor language, and surfaces every other maker's equivalent designation at the same boundary dimensions. Per Codex source extraction (May 2026): SKF Rolling Bearings 17000 EN, Schaeffler HR 1, Timken DGBB 10857 + Tapered 10481 + Spherical 10446 + Cylindrical 10447, NSK E1103, NTN 2203/E, Koyo BS004EN. The cross-vendor translation is intent-level, not string-level: two contact seals is the same intent whether the maker calls it 2RS1 or 2RSH (SKF), DDU (NSK), LLU (NTN), 2RSR (FAG), or 2RS (Timken / Koyo / legacy). Suffix tokens carry the source catalog page, the parsed intent, and a confidence label. Deep-groove-ball clearance class C2 through C5 is explained in microns per ISO 5753-1 by bore size; roller-bearing clearance suffixes are decoded but their micron ranges are suppressed because cylindrical and spherical roller families use materially different tables. Every decode produces prefill links to the six existing ToolGrit bearing calculators (life, speed limit, grease, load, failure triage, puller force) so the same decoded geometry feeds the application math. Legacy brand support handles source-verified MRC mappings, low-confidence Fafnir and RHP lookups, and recognizes Bower without shipping an unverified Bower cross-reference.

Pro Tip: When two makers both list a "6205" they share the ISO 15 boundary dimensions (25 mm bore, 52 mm OD, 15 mm width) but they do not necessarily share the dynamic load rating C, the limiting speed, or the cage design. SKF's baseline C for 6205 is 14.8 kN; another maker may publish 13.0 to 16.5 kN for the same designation depending on internal design. If you are sizing for L10 life or speed margin, pull the actual rating from the maker you are buying from, not from the cross-vendor table. The decoder gives you the geometric replacement; the application math is in the six bearing calculators.

Read the Bearing Decoder Guide for SKF, FAG, Timken numbering rules and a worked example

Bearing Decoder Guide →

Once decoded, run the L10 fatigue life with the dynamic load rating prefilled

Bearing L10 Life Calculator →

Check the operating speed against the ndm limit with bore and OD prefilled

Bearing Speed Limit Calculator →

Get a re-lubrication interval recommendation with bore, OD, and RPM prefilled

Bearing Grease Interval Calculator →

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Bearing Part Number Decoder
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How It Works

  1. Pick or Paste a Bearing Part Number

    Type the designation in the input field, or click an example chip to load a worked-out designation. The brand prefix (SKF, FAG, Timken, NSK, NTN, Koyo) is optional. When present, the decoder auto-detects the manufacturer and applies that maker's suffix dictionary. Without a brand prefix, the decoder defaults to SKF parsing rules, which cover the same numbering conventions used by most makers for the basic designation. Spaces, hyphens, and slashes are all treated as separators. Case is preserved on output but normalized internally.

  2. Read the Hero Panel

    The first card after decoding shows the bearing type (deep groove ball, angular contact ball, cylindrical roller, spherical roller, etc.), the basic designation parsed from your input, and the boundary dimensions (bore x OD x width in mm) pulled from the V1 ISO 15 lookup table. When SKF reference and limiting speeds are source-verified for that row, the same panel shows them as open-variant speed ratings. The four chips below show the load and misalignment character of this bearing family (radial load, axial load, misalignment tolerance, row count). Use these to confirm the bearing matches the application.

  3. Read the Plain-English Summary

    The plain-English summary is the one-line spec sheet sentence you would write by hand: manufacturer, basic designation, bearing type, boundary dimensions, closure (seal or shield), clearance class, cage. Suitable for a spec sheet, an email, or a purchase requisition.

  4. Read the Suffix Breakdown

    Every suffix token is parsed against the manufacturer's suffix dictionary and grouped by category (internal design, cage, sealing / shielding, clearance, precision, matched set). Each row shows the raw token, the plain-English meaning, the confidence label, and the source catalog page when known. Suffix tokens that are not in the V1 dictionary are flagged in the "Could not decode" section rather than silently guessed.

  5. Read the Clearance Class Card

    When a clearance suffix (C2, C3, C4, C5) is decoded on a deep groove ball bearing, the tool surfaces the radial internal clearance in microns from ISO 5753-1:2009 for the matched bore size. For cylindrical and spherical roller bearings, the class is decoded but the micron range is suppressed because those product families use different clearance tables. The scope text explains when the class is right (e.g., C3 is common in TEFC motor bearings to compensate for inner-ring thermal expansion).

  6. Read the Cross-Vendor Equivalents

    The cross-vendor table shows the other makers' designations for the same ISO 15 boundary dimensions, with the same decoded closure and clearance intents projected into each maker's vocabulary. The equivalence level is labeled (Catalog match / Same size class / Likely equivalent / Maker-listed / Unverified). "Same size class" means the boundary dimensions match per ISO 15. "Likely equivalent" means dimensions plus closure plus clearance intents all align. The notes column reminds the user that cage and seal-material details can still differ even when the basic designation matches.

  7. Use the Prefill Links to Run the Bearing Calculators

    Six links open the matching ToolGrit calculator with the decoded geometry pre-populated: bearing speed limit (bore, OD, type preset), bearing life (dynamic load rating C, ball or roller exponent), bearing grease interval (bore, OD), bearing load (bearing type), failure triage (bearing type), and puller force (bore, OD). You supply the application-specific inputs (operating RPM, applied load, environment, hours per day). The decoder is the front door to the application math.

  8. Export the Decoded Report

    PDF export produces a branded, page-break-safe report with every decoded position, every parsed suffix, the clearance microns, the cross-vendor table, and the prefill links. Suitable for handing to a supervisor, a parts buyer, or a coworker who needs to confirm an order. CSV export packages the same fields for spreadsheet import. Share-URL encoding lets a coworker open the exact same decode without retyping.

Built For

  • Plant maintenance tech walking up to a TEFC motor with a 6308-2RS1/C3 stamping on the bearing and confirming the replacement spec
  • Parts buyer cross-referencing a Fafnir 205PP3 from a 30-year-old conveyor drive to the current Timken or SKF equivalent
  • Reliability engineer auditing a spherical-roller-bearing replacement on a vibrating screen: 22210-E1-K-C3 vs SKF 22210 EK + adapter sleeve
  • Motor shop tech ordering replacement bearings for a TEFC service: 6206-2Z (one motor) and 6308-2RS1/C3 (other motor) and confirming both have the right clearance
  • Pump tech replacing the thrust angular-contact bearings on a multistage pump: 7207B vs 7207AC contact angle and DB vs DF matched pair
  • Junior planner who has never decoded a bearing number before, learning by example what 2RS, ZZ, C3, M, TN9 actually mean
  • CMMS data steward standardizing 200 bearing entries that came in with brand-mixed designations (2RS, DDU, LLU, 2RSR all in the same database)
  • Inspector confirming a stainless deep-groove ball bearing replacement matches the original (W6205 SKF stainless prefix)
  • Conveyor mechanic decoding a self-aligning ball 1207 vs spherical-roller 22207 and picking the right type for the misalignment service
  • Vibration tech reading a NU310 from a traction motor and confirming the cylindrical roller family before pulling vibration spectra for the right failure mode

Features & Capabilities

Six Manufacturers, Source-Cited Per Catalog

Supports SKF (Rolling Bearings 17000 EN), FAG / Schaeffler (HR 1), Timken (Deep Groove 10857 + Tapered 10481 + Spherical 10446 + Cylindrical 10447), NSK (E1103 industrial machinery), NTN (2203/E ball and roller bearings, plus boundary dimensions and bearing-number-codes section), and Koyo / JTEKT (BS004EN technical section and standard tables). Source catalogs are cited on the source banner and on every decoded suffix where the page is known.

Grammar-Driven, Not a Flat Lookup

The decoder is built around the structural shape of bearing designations: prefix tokens (W for stainless, etc.) + basic designation (type code + dimension series + bore code) + suffix tokens (internal design, cage, sealing / shielding, clearance, precision, matched set, lubricant). The basic designation is parsed by regex against per-maker family patterns. The bore code follows the universal ISO rule: 00 = 10 mm, 01 = 12 mm, 02 = 15 mm, 03 = 17 mm, then 04 and up is code times 5. Slash-bypass bore notation (60/22 means literal 22 mm) is handled explicitly. Suffix tokens are parsed by longest-match against the maker-specific dictionary.

Intent-Level Cross-Vendor Translation

Cross-vendor equivalence is computed by normalizing maker-specific suffix tokens into a canonical intent (e.g., two_contact_seals, two_shields, C3 clearance), then projecting that intent back into each other maker's vocabulary. The result: a single decode of SKF 6205-2RS1/C3 produces FAG 6205-2RSR/C3, Timken 6205-2RS/C3, NSK 6205-DDU/C3, NTN 6205-LLU/C3, and Koyo 6205-2RS/C3 in the current tool output. Equivalence is labeled at five levels: Catalog match, Same size class, Likely equivalent, Maker-listed, Unverified.

Boundary Dimensions Per ISO 15:2017

V1 boundary dimensions cover deep groove ball (6000, 6200, 6300, 6400 series), angular contact ball (7200, 7300 series), cylindrical roller single row (NU/NJ/N/NUP 200 and 300 series), spherical roller (22200, 22300 series and select 23000 sizes), and self-aligning ball (1200 and 1300 series). Each row carries bore, OD, width, and, where source-verified, SKF baseline dynamic load rating C, static rating C0, reference speed, and limiting speed. Load and speed values are audited against SKF product tables; boundary dimensions are checked against the captured maker catalog set.

ISO 5753-1:2009 Clearance Class Lookup

When a clearance suffix (C2, C3, C4, C5) is decoded on a deep groove ball bearing, the tool reports the radial internal clearance in microns for the matched bore size per SKF Rolling Bearings 17000 EN table 6. Bore ranges from 2.5 to 140 mm are tabulated in V1. Cylindrical and spherical roller clearance suffixes are decoded, but their micron values are suppressed until the correct roller-bearing tables are added. Scope text explains each class in plain English: C3 is common in TEFC motor bearings to compensate for inner-ring thermal expansion, C4 is for hot service or heavy interference fit, C5 is rare on standard maintenance bearings.

Field Notes That the Catalog Does Not Print

Three field-truth callouts surface when relevant: the C3-and-motor-bearings rule (most TEFC motors spec C3 for thermal compensation), the C3-over-spec trap (do not default to C3 for cool-running, lightly loaded service), and the polyamide-cage temperature limit (TN9 / TVH / TVP / T / TR cages have a continuous-temperature ceiling around 120 C; hard limit around 150 C; choose machined-brass cage for higher temperatures). These notes appear only when the relevant suffix is present, not as boilerplate.

Legacy Brand Alias Handling

MRC part numbers are mapped to source-verified SKF equivalents, while Fafnir and RHP starter mappings are retained with low confidence until a better legacy catalog source is added. Bower is recognized as a legacy brand name, but no Bower part-number cross-reference is shipped in V1 because the captured source set did not verify one. The decoder shows the legacy origin in a callout, then resolves the modern designation and runs the standard cross-vendor + prefill flow on the modern equivalent.

Prefills All Six Bearing Calculators

Every successful decode produces prefill URLs for the six existing ToolGrit bearing calculators: bearing-life-calc (life with dynamic load rating C and ball / roller exponent), bearing-speed-limit-calc (ndm check with bore, OD, type preset), bearing-grease-calc (re-lubrication interval with bore, OD, RPM placeholder), bearing-load-calc (equivalent load with bearing type preset), bearing-failure-triage (diagnostic with bearing type preset), and bearing-puller-force-calc (puller force with bore and OD). The decoder is the hub; the six calculators are the spokes.

Honest Confidence Labels

Every decoded suffix and every cross-vendor row carries a confidence label: high (catalog-verified), medium (verified with interpretation), low (inferred), or unverified (prior only, not source-confirmed). When a suffix is not in the V1 dictionary, it is flagged as Could not decode rather than silently guessed. The decoder errs on the side of admitting what it does not know.

PDF and CSV Export

PDF export uses the shared ToolGrit programmatic PDF generator. The decoded report fits on two to three pages with no row mid-split, no orphan headings, and a branded header and disclaimer footer. CSV export packages the input, manufacturer, basic designation, boundary dimensions, every decoded suffix with category and source page, every cross-vendor row, and every prefill link summary. Share-URL encoding lets a coworker open the exact same decode without retyping.

Light and Dark Mode, Mobile-Friendly

Standard ToolGrit light and dark theme with WCAG AA contrast throughout. The decoded output collapses cleanly to mobile at 375 px viewport without horizontal scrolling. The hero panel and plain-English summary are screen-reader-friendly aria-live regions so accessibility tools announce the decoded result when the input changes.

Comparison

Two-contact-seal intent Suffix code Source catalog
SKF 2RS1 or 2RSH SKF Rolling Bearings 17000 EN, designation system p. 35 and product tables
FAG (Schaeffler) 2RSR Schaeffler HR 1 designation chapter
Timken 2RS Timken Deep Groove Ball 10857 p. 22
NSK DDU NSK E1103 supplementary designations chapter
NTN LLU NTN 2203/E bearing-number-codes section, pp. A-48 to A-51
Koyo (JTEKT) 2RU or 2RS Koyo BS004EN-2DS technical section A-52+

References

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Frequently Asked Questions

The bearing bore-code rule is piecewise. Codes 00, 01, 02, 03 are exceptions: 00 = 10 mm, 01 = 12 mm, 02 = 15 mm, 03 = 17 mm. Codes 04 and up follow the multiplier rule: bore in mm = code times 5. So 04 = 20 mm, 05 = 25 mm, 10 = 50 mm, and 96 = 480 mm. The rule is universal across SKF, Timken, NSK, NTN, MRC, and most other makers for common metric radial families. A reading of "6204 means 4 mm bore" is the single most common bearing-decoding mistake, and the decoder catches it.
Yes, but with a low-confidence label until a better unmounted Fafnir source is added. Fafnir was acquired by Timken (via Torrington) in 2003. The decoder recognizes the Fafnir brand prefix and maps 205PP to Timken 6205-2RS (deep groove ball, 25 mm bore, contact rubber seals both sides). MRC mappings are source-verified from the MRC handbook. Bower is recognized as a legacy brand name, but V1 does not ship a Bower cross-reference because the captured source set did not verify one.
They are the same intent (two contact rubber seals) at the same boundary dimensions, but they are not necessarily identical construction. SKF 2RS1 specifies NBR (nitrile) seal material on the standard product; SKF 2RS2 is fluororubber (FKM) for high-temperature or chemical service. NSK's DDU is also typically NBR but the cage design and the precise seal-lip geometry are not standardized across makers. For most general-purpose plant maintenance service, the two are functionally interchangeable. For hot service, chemical service, or precision-spindle service, confirm the seal material and the temperature rating against the maker catalog before treating as a drop-in replacement.
That is the radial internal clearance range in microns per ISO 5753-1:2009 for a deep groove ball bearing C3 class at your bore size. Internal clearance is the play that exists between the inner ring, the rolling elements, and the outer ring before the bearing is mounted. When the bearing is mounted onto a shaft with an interference fit, some of that clearance is consumed. When the inner ring heats up (running on a hot shaft, hot service environment), the inner ring grows thermally and consumes more of the clearance. C3 is chosen when the operating condition will eat up enough of the unmounted clearance that a Normal-class bearing would end up with zero or negative clearance, which causes preload, heat, and short life. For cool-running, lightly loaded service, choosing C3 over-specifies and increases vibration; CN is the right call.
Cross-vendor equivalence is computed from ISO 15 boundary dimensions plus the closure and clearance intent normalization. That is enough to confirm geometric interchangeability (the replacement will physically fit). It is not enough to confirm functional interchangeability (the dynamic load rating C, the limiting speed, the cage material, the seal compound, the internal geometry refinements can still vary). Two makers' "6205" share bore / OD / width but may have 10 to 20 percent different load ratings depending on internal design (E or EC enhanced variants run higher). For routine motor or general-machine service the substitution is typically fine; for spindle service, life-critical applications, or precision matched-set arrangements, verify the maker's full specifications.
K means the bore is tapered with a 1:12 taper, intended for mounting on an adapter sleeve rather than directly onto a shaft. The mounting procedure is different from a cylindrical-bore bearing: the adapter sleeve threads onto the shaft, the bearing inner ring is pressed onto the sleeve's taper, and the locknut on the sleeve provides the axial location and the interference fit. K30 is a 1:30 taper for very large spherical rollers (paper-machine tension rolls and similar). If you order a 22210K when the shaft is a plain cylindrical shaft, the bearing will not mount correctly. The decoder calls out the bore prep intent (tapered 1:12 or 1:30) so the mounting procedure is obvious.
Not yet. Timken inch-series tapered roller designations (HM, LM, JLM, JM, etc.) are not decomposable from a formula; they are an enumerated catalog. The cone and the cup are separate part numbers within a matched set. V1 supports metric tapered roller (30207, 32208, 33205 style) as a recognized family hint but does not extract full geometry without the matching maker product table. Timken eCatalog inch lookup is on the roadmap for V2. For now, if you paste an inch-series Timken number, the decoder flags it as an out-of-scope family with a clear message and a link to the Timken eCatalog.
Maker configurators build new orders against their current catalog only. They cannot decode a legacy Fafnir or MRC tag, they cannot cross-reference one maker to another, and they require you to know which maker before you start. The ToolGrit decoder reads a finished part number from any of six makers (plus four legacy brands), shows what every position means, and surfaces the cross-vendor equivalents in a single view. It is a maintenance and planning helper that sits between the existing tag on a shelf and the application math in the six bearing calculators. It is not a substitute for ordering through an authorized distributor; the disclaimer on every decode reads "Verify all calculations independently before making purchase or safety decisions."

Learn More

Shops & Outbuildings

Bearing Decoder Guide: Read SKF, FAG, Timken, NSK, NTN, Koyo Numbering

How to read a bearing part number across all six major makers. Bore code rule, suffix categories, intent-level cross-vendor translation, clearance class microns from ISO 5753-1, legacy brand aliases (Fafnir, MRC, Bower, RHP). Companion to the Bearing Part Number Decoder.

Read Guide →

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