---
title: "Engineering Reference"
description: "Engineering reference tables: thread dimensions, property classes, torque, tap-drill and clearance-hole sizes."
url: https://engineeringhardware.com/fasteners/reference/
source: Engineering Hardware & Fasteners
---

# Engineering Reference

Catalog

Engineering reference tables: thread dimensions, property classes, torque, tap-drill and clearance-hole sizes.

[Bolt Property Classes **Standard:** ISO 898-1 **Type:** Bolt Property Classes **Sizes:** 10 listed View sizes & specs →](https://engineeringhardware.com/fastener/bolt-property-classes/)

[Clearance Hole Sizes **Standard:** ISO 273 **Type:** Clearance Hole Sizes **Sizes:** 33 listed View sizes & specs →](https://engineeringhardware.com/fastener/clearance-hole-sizes/)

[Metric Fine Thread Dimensions **Standard:** ISO 724 **Type:** Metric Fine Thread Dimensions **Sizes:** 36 listed View sizes & specs →](https://engineeringhardware.com/fastener/metric-fine-thread-dimensions/)

[Metric Thread Dimensions **Standard:** ISO 724 / ISO 965 **Type:** Metric Thread Dimensions **Sizes:** 43 listed View sizes & specs →](https://engineeringhardware.com/fastener/metric-thread-dimensions/)

[Tap Drill Sizes **Standard:** ISO 2306 (reference) **Type:** Tap Drill Sizes **Sizes:** 47 listed View sizes & specs →](https://engineeringhardware.com/fastener/tap-drill-sizes/)

[Tightening Torque Reference **Standard:** Calculated (see note); not specified by ISO 898 **Type:** Tightening Torque Reference **Sizes:** 15 listed View sizes & specs →](https://engineeringhardware.com/fastener/tightening-torque-reference/)

## Not sure which fastener you need?

Use the finder to filter by category, standard, size and material, then request a quote.