Taper Roller Bearing Size Chart: Metric & Inch Dimensions (d/D/T)

A taper bearing's part number already tells you its size — if you know how to read it.

This chart covers the two dimension systems you'll actually run into on a sourcing job: the ISO 355 metric series (used by SKF, NTN, Koyo, and most Chinese manufacturers) and the ABMA inch series (the Timken-style numbering common in North American automotive and trailer applications).

Every dimension below — bore (d), outside diameter (D), width (T), and dynamic/static load ratings — is pulled from manufacturer dimension tables and cross-checked against at least one independent supplier listing for the same part number.

Where a figure couldn't be verified against a second source, it's left out rather than estimated.

When we're matching a worn or relabeled tapered bearing against a chart like this for a customer, width is usually the dimension that trips people up — bore and OD are easy to confirm with calipers, but width gets missed when a cone and cup from different production runs are already stacked together.

The Three Dimensions That Define Every Tapered Roller Bearing

Before the chart, three letters you'll see on every drawing and every supplier spec sheet:

• d — Bore diameter. The inside diameter of the cone (inner ring). This is what sits on the shaft.

• D — Outside diameter. The outside diameter of the cup (outer ring). This is what sits in the housing.

• T is different from the first two: it's not a single ring's dimension but the assembled stack height of cone + cup + rollers, measured axially once everything is seated together.

A tapered roller bearing is always sold as two separable parts — the cone (inner ring, rollers, and cage) and the cup (outer ring) — so d and D always belong to different components, even though they're listed on the same line in a chart.

That separability has a practical consequence: cone and cup from two different bearings of the same series and same manufacturer are usually interchangeable.

A cone from one brand generally shouldn't be paired with a cup from another, though, unless the manufacturer explicitly certifies cross-brand interchange for that size.

Metric Series (30200) Size Chart — mm

The 30200 series is one of the most widely used metric tapered roller bearing lines, with a standard contact angle of roughly 10–16°.

Dimensions and basic load ratings below follow DIN ISO 355 / DIN 720 and make up the core of this taper roller bearing size chart.

Bores above 100 mm, steeper contact angles, or double-row configurations fall outside this table — the 30300, 31300, 32000, 32200, 32300, and 33000 series cover bores from roughly 35 mm up to 400+ mm with progressively steeper contact angles for higher axial load capacity, and are worth a separate lookup once you're outside the 30200 range.

Browse the complete metric tapered roller bearing catalog for additional sizes, current stock, and pricing.

Inch Series Size Chart — Common ABMA/Timken-Style Sets

Inch-series tapered roller bearings are identified by a cone/cup set number rather than a sequential code, so there's no shortcut formula — you look the number up.

The five sets below are among the most widely stocked, spanning the 1"–1.78" bore range common in trailer hubs, light agricultural equipment, and gearboxes.

Already working with an L44643? We've published a full breakdown of its tolerances, housing fit, and interchange notes in our L44643 bearing guide.

Browse the complete inch (imperial) tapered roller bearing catalog for additional cone/cup sets, current stock, and pricing.

Metric vs. Inch vs. JIS: How to Tell Which System You're Looking At

• Metric (ISO 355): Part number is a 4–5 digit code (30206, 32010). Dimensions in mm. Dominant in Europe, China, and most non-automotive industrial equipment.

• Inch (ABMA): Part number is an alphanumeric set code (L44643, LM67048, HM212049) with no fixed digit-to-dimension relationship. Dimensions in inches, sometimes dual-marked in mm. Dominant in North American trailer, agricultural, and legacy automotive applications.

• JIS: Follows the same numeric logic as ISO metric series but with Japan-specific tolerance classes; JIS-series bearings from Koyo, NSK, and NTN are generally dimensionally compatible with ISO metric equivalents of the same number, though precision-grade units should be matched to the same manufacturer.

If you're replacing a bearing and only have the housing bore and shaft diameter (no legible part number), match those two figures to the D and d columns above — but treat width (T) as the tie-breaker, since several bearings can share the same d/D combination with different widths.

Reading the Suffix Letters

Beyond the base number, letter suffixes change fit and performance:

• C (metric series) — medium contact angle (roughly 17–24°, vs. 10–16° standard), added when axial load capacity needs to increase without changing the bore/OD footprint.

• J (inch series) — cup angle and raceway diameter conform to ISO 355, used where dimensional interchange with metric equivalents matters.

• X — steep-angle variant (24°+), for applications with heavy one-directional axial loading.

None of these change d, D, or T — they change the internal geometry and load rating, so always confirm the suffix matches your original part before ordering a replacement.

Measuring an Unmarked Bearing

If the part number is worn off:

1. Measure bore (d) and cup OD (D) with calipers, not a tape measure — tapered geometry makes tape measurements unreliable.

2. Measure overall width (T) with the cone and cup fully seated together.

3. Count the rollers if possible; combined with d/D/T, roller count narrows the match to one or two candidates in most catalogs.

4. Cross-check against the chart above by d and D first, then confirm with T.

FAQ

Why are tapered roller bearings sold as two separate parts instead of one sealed unit?

Because the cone and cup need to be adjustable relative to each other during mounting. Unlike a sealed ball bearing, a tapered roller bearing's operating clearance (endplay or preload) is set at installation by how far the cone is pushed onto the shaft relative to the cup — that adjustment isn't possible if the two rings are permanently joined. Selling them separable also lets a worn cup be replaced without discarding a still-good cone, or vice versa.

Can a 30206 and a 30206C be swapped without changing the housing or shaft?

Yes for the fit, no for the load behavior. The "C" suffix changes only the internal contact angle (roughly 17–24° vs. 10–16° standard) — bore, OD, and width stay identical, so it drops into the same housing and shaft. What changes is axial load capacity: a 30206C carries more thrust load than a standard 30206 in the same envelope, so swapping one in without re-checking the application's axial load isn't a like-for-like substitution.

Why do two suppliers sometimes list different width numbers for the same inch-series set?

"Width" isn't measured from the same reference point across catalogs. Some suppliers publish cone width alone, some publish cup width alone, and some publish the assembled overall width — three different numbers for the same physical part. If a quoted width doesn't match what you measured, check which of the three the supplier means before assuming it's the wrong part.

What's the fastest way to check a metric taper bearing's bore without a chart on hand?

Take the last two digits of the part number and multiply by 5 — that's the bore in mm, as long as the number is 04 or higher. A 32024, for example, decodes to a 120 mm bore (24 × 5), which matches its published spec. Numbers ending in /22, /28, or /32 are exceptions and read directly as the bore in mm.

Is a Timken cone interchangeable with an SKF cup of the same size?

Only if the specific part number is listed as cross-brand interchangeable by at least one of the two manufacturers — matching d, D, and T isn't enough on its own. ISO 355 and ABMA standardize the boundary dimensions, but internal geometry, contact angle, and precision tolerances aren't guaranteed to match across brands even when the outer dimensions do. For anything load-critical, request the manufacturer's interchange documentation rather than assuming compatibility from the size chart alone. Our bearing cross-reference tool can help identify certified equivalents across brands.