Thread Size Cross-Reference
Free thread size cross reference: paste a thread callout and map metric, UNC/UNF, BSP/BSPT, and NPT designations. Runs in your browser, no upload.
This thread size cross reference tool takes a thread callout — like M10x1.5, 3/8-16 UNC, or 1/2 BSP — and maps it across the major thread standards, so the same fastener or fitting reads consistently no matter which supplier described it. Paste a single callout or a column of them and get nominal diameter, pitch or threads-per-inch, and the equivalent designation in each system.
Thread Size Cross-Reference
The interactive version of this tool is coming soon. It will run entirely in your browser — no login, no upload limits.
Planned tool: thread size cross reference
Need this now? Talk to ClaroWhat it checks
For each thread callout you enter, the tool parses and returns:
- Standard family — whether the callout is metric (ISO 261 / ISO 965), Unified inch (UNC / UNF / UNEF, ASME B1.1), British pipe (BSPP / BSPT, ISO 228 / ISO 7), or American pipe (NPT / NPSM, ASME B1.20.1).
- Nominal diameter — the major diameter in both millimetres and inches, so a
3/8callout and a9.5 mmcallout resolve to the same row. - Pitch and threads per inch — pitch in mm for metric threads, TPI for inch threads, with the coarse/fine distinction (for example UNC vs UNF at the same diameter).
- Cross-reference equivalents — the nearest match in each other standard, flagged clearly as an exact equivalent or a “closest, not interchangeable” approximation.
- Tapered vs parallel — whether the thread is parallel (BSPP, metric machine threads) or tapered (NPT, BSPT), since these do not interchange even when the size label looks similar.
- Parse warnings — ambiguous or malformed callouts (a bare
3/8with no standard, a metric pitch that does not exist for that diameter) are surfaced rather than silently coerced.
How the thread size cross reference works
Thread designations encode three independent facts: the standard, the nominal diameter, and the pitch. The tool normalizes each callout to that canonical triple, then looks up neighbours in a static table built from the published standards (ISO 261/965 for metric, ASME B1.1 for Unified, ISO 228/7 for British pipe, ASME B1.20.1 for NPT). Matching on the normalized triple — not on the raw text — is what lets M10 x 1.5, M10x1.50, and 10mm coarse all resolve to the same canonical thread.
- 1Parse the callout
Diameter, pitch/TPI, and any standard prefix or suffix are extracted from free-text input, tolerant of spacing, case, and punctuation variants.
- 2Normalize to a canonical thread
Units are reconciled (inch to mm), the standard family is inferred where it is unambiguous, and coarse/fine series are resolved.
- 3Cross-reference and grade
The canonical thread is matched against each other standard, and every equivalent is graded as exact, approximate, or non-interchangeable.
All parsing and lookup happen client-side in your browser. Nothing you paste is uploaded to a server, which means you can run a supplier’s MRO spreadsheet or a furniture fittings list through it without moving data outside your machine. This makes it a safe first pass for distributors cleaning inbound supplier feeds before they reach a PIM or ERP — the same normalization logic that production data normalization pipelines apply, available as a quick manual check.
Related resources
Playbook
Identify a Thread From Diameter and Pitch
Work backwards from a measured diameter and pitch to a standard thread designation, step by step.
Glossary
BSP Thread Dimensions Reference
Nominal sizes, TPI, and pitch for the British pipe thread series, parallel and tapered.
Tool
Unit & Dimension Converter
Convert product dimensions and units so inch and metric specs reconcile in one catalog.
Guide
58 Fields in a Complete Product Record
What a fully enriched fastener or fitting record needs before it is channel-ready.
Claro
Attribute Enrichment
See how Claro fills thread, dimension, and material attributes at catalog scale with provenance on every value.
FAQ
What is a thread size cross-reference used for?
It maps a thread designation from one standard to its equivalent in others — for example matching an imperial UNC callout from a US supplier to the metric ISO thread your catalog uses. Distributors rely on it when consolidating MRO, fasteners, and fittings from multiple suppliers into a single normalized inventory, so the same physical part is not listed two or three different ways.
Are metric and imperial threads interchangeable?
Almost never. A few sizes are dimensionally close (a 1/4-20 UNC and an M6 are similar but not identical), but the diameters and pitches differ enough that mixing them risks cross-threading or a loose fit. The tool labels these as approximate matches rather than exact equivalents so they are not treated as the same part during enrichment.
Is BSP the same as NPT?
No. Both are pipe thread standards with overlapping nominal sizes, but BSP uses a 55-degree thread form and NPT uses 60 degrees, and the taper and sealing behaviour differ. A “1/2 BSP” and a “1/2 NPT” share a label but are distinct parts, which is why the cross-reference flags pipe-thread equivalents as non-interchangeable.
Does the tool upload my data anywhere?
No. All parsing and lookup run entirely in your browser. You can paste a full column of thread callouts from a supplier price file or product sheet, and nothing leaves your machine — there is no login and no file-size limit.
How do I read a callout like M10x1.5?
M marks it as an ISO metric thread, 10 is the nominal major diameter in millimetres, and 1.5 is the pitch in millimetres (the distance between adjacent threads). An inch callout like 3/8-16 UNC reads as a 3/8-inch diameter, 16 threads per inch, coarse Unified series. The cross-reference returns both representations side by side.