Free tool
Thread Size Cross-Reference
Look up thread sizes across ISO Metric, BSP, and NPT. Auto-detects the system, validates designations, shows nearest equivalents.
What this tool checks
Checks
- ✓ Thread system auto-detection (ISO Metric, BSP, NPT)
- ✓ Whether the designation matches a standard size
- ✓ Major diameter and pitch/TPI for the matched size
- ✓ Cross-references to nearest sizes in other systems
- ✓ Suggestion of nearest valid size for non-standard input
Does not check
- ✗ Thread tolerance classes or fit (6g/6H, Class 1/2/3)
- ✗ Left-hand thread designation (LH)
- ✗ Actual interchangeability between systems
- ✗ UNC, UNF, or other ANSI unified thread series
- ✗ Thread length, engagement depth, or torque specs
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Comparison
NPT vs BSP vs Metric Threads: How to Tell Them Apart
A practical comparison of the three major thread systems: NPT (National Pipe Thread), BSP (British Standard Pipe), and ISO Metric. Covers physical differences, measurement methods, and how to identify each from a fitting.
Playbook
How to Identify a Thread from Diameter and Pitch
Step-by-step guide to identifying thread standards from physical measurements. Covers tools needed, measurement technique, and how to cross-reference diameter and pitch to determine NPT, BSP, or Metric thread type.