Thread center

Thread Size and Pitch Reference

A thread designation combines diameter, pitch or TPI, profile and tolerance context. These references help identify the system before choosing a drill, tap or fastener.

INTERACTIVE TOOL

Thread Pitch Converter

Convert millimeter pitch and TPI using an exact rational calculation.

Open tool →

Reference library

Focused pages with a clear owner

Each URL answers a distinct question. ThreadSizeGuide avoids automatically generating thin pages for every possible size.

Thread reference

UNC and UNF Thread Chart: Diameter, TPI and Tap Drill Context

Compare common Unified coarse and fine threads without confusing nominal diameter, TPI and tap drill size.

Read reference →Thread reference

Metric Thread Pitch Chart and Identification Guide

Understand metric thread callouts, coarse and fine pitches, and conversion to threads per inch.

Read reference →Unified thread comparison

UNC vs UNF Threads

Compare Unified coarse and fine thread series by pitch, identification, tapping behavior and application tradeoffs.

Read reference →