--- title: "Clearance Hole Sizes" description: "Clearance Hole Sizes to ISO 273: sizes M1 to M64. 33 catalogued sizes with materials and finishes. Technical drawing redraws to any row." url: https://engineeringhardware.com/fastener/clearance-hole-sizes/ source: Engineering Hardware & Fasteners --- # Clearance Hole Sizes Engineering Reference · Clearance Hole Sizes 33 catalogued sizes, dimensioned to ISO 273. Pick any row and the technical drawing redraws to it. Clearance Hole Sizes to ISO 273 are catalogued in sizes M1 to M64. 33 sizes are held in the table below, and the technical drawing redraws to whichever row you select. - **Standard:** ISO 273 - **Size range:** M1-M64 - **Catalogued sizes:** 33 Dimensions are nominal values from the governing standard. Confirm the tolerance class for your application before ordering. ![Clearance Hole Sizes technical product image](https://engineeringhardware.com/wp-content/uploads/2026/06/Hex-Bolts-—-ISO-4014-／-ISO-4017-Detail.webp) Clearance Hole Sizes conform to ISO 273. As engineering reference, they are specified by the dimensions in the table below; this page also covers materials, finishes and typical uses. ## About This Reference This is an engineering reference table for clearance hole sizes based on ISO 273. Use it alongside our fastener catalog when selecting and specifying parts. ## Reference Data (ISO 273) | Thread size | Fine H12 (mm) | Medium H13 (mm) | Coarse H14 (mm) | Reference standard | Application | | --- | --- | --- | --- | --- | --- | | M1 | 1.1 | 1.2 | 1.3 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M1.2 | 1.3 | 1.4 | 1.5 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M1.4 | 1.5 | 1.6 | 1.8 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M1.6 | 1.7 | 1.8 | 2.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M2 | 2.2 | 2.4 | 2.6 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M2.5 | 2.7 | 2.9 | 3.1 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M3 | 3.2 | 3.4 | 3.6 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M3.5 | 3.7 | 3.9 | 4.2 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M4 | 4.3 | 4.5 | 4.8 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M5 | 5.3 | 5.5 | 5.8 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M6 | 6.4 | 6.6 | 7.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M7 | 7.4 | 7.6 | 8.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M8 | 8.4 | 9.0 | 10.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M10 | 10.5 | 11.0 | 12.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M12 | 13.0 | 13.5 | 14.5 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M14 | 15.0 | 15.5 | 16.5 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M16 | 17.0 | 17.5 | 18.5 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M18 | 19.0 | 20.0 | 21.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M20 | 21.0 | 22.0 | 24.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M22 | 23.0 | 24.0 | 26.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M24 | 25.0 | 26.0 | 28.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M27 | 28.0 | 30.0 | 32.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M30 | 31.0 | 33.0 | 35.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M33 | 34.0 | 36.0 | 38.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M36 | 37.0 | 39.0 | 42.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M39 | 40.0 | 42.0 | 45.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M42 | 43.0 | 45.0 | 48.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M45 | 46.0 | 48.0 | 52.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M48 | 50.0 | 52.0 | 56.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M52 | 54.0 | 56.0 | 62.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M56 | 58.0 | 62.0 | 66.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M60 | 62.0 | 66.0 | 70.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | | M64 | 66.0 | 70.0 | 74.0 | ISO 273 / DIN 406 | Clearance (through) hole, non-threaded | Inside the plant ## Manufactured in our own plant This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided. 1. ![Wire rod feeding into a cold heading machine](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 01 **Cold heading** Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail. Head dimensions and under-head radius checked at set-up and per shift. 2. ![Thread rolling machine producing bolt threads](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 02 **Thread rolling** Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch. Go / no-go ring gauges to ISO 965 tolerance class 6g. 3. ![Baskets of bolts staged for heat treatment](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 03 **Heat treatment** Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it. Core hardness and tensile tested per lot to ISO 898-1. 4. ![Zinc plated bolts in a treatment basket](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 04 **Surface treatment** Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list. Coating thickness and neutral salt spray hours to ISO 9227. ## Frequently Asked Questions ### What does the Clearance Hole Sizes reference table cover? Clearance Hole Sizes is an engineering reference table aligned with ISO 273. Use the values alongside our fastener catalog when selecting and specifying parts. ### How do I request a quotation? Use the parametric drawing on this page to set the exact configuration (size, material, finish) and click "Request this configuration" — a specialist from Engineering Hardware will respond within one business day.