--- title: "M4 Hex Head Bolt Dimensions" description: "M4 Hex Head Bolt: width across flats (spanner size) 7 mm, head height 2.8 mm, coarse thread pitch 0.7 mm. Tightening torque 2.9 Nm at class 8.8." url: https://engineeringhardware.com/guide/size/m4-cad-svg-001-hexbolt/ source: Engineering Hardware & Fasteners --- # M4 Hex Head Bolt Dimensions Bolts · GB/T 5782 / ISO 4014 Controlling dimensions to GB/T 5782 / ISO 4014, with clearance hole and tapping drill, spanner or drive size and tightening torque. M4 Hex Head Bolt dimensions to GB/T 5782 / ISO 4014: width across flats (spanner size) 7 mm, head height 2.8 mm, coarse thread pitch 0.7 mm, clearance hole (ISO 273 medium) 4.5 mm. Tighten to approximately 2.9 Nm at property class 8.8 in a dry, as-supplied condition. - **Width across flats (spanner size):** 7 mm - **Head height:** 2.8 mm - **Coarse thread pitch:** 0.7 mm - **Clearance hole (ISO 273 medium):** 4.5 mm - **Tightening torque (class 8.8):** 2.9 Nm Figures are nominal values from the governing standard. Confirm against the tolerance class for your application before machining or ordering. ![M4 Hex Head Bolt Dimensions reference image](https://engineeringhardware.com/wp-content/uploads/2026/06/Hex-Bolts-—-ISO-4014-／-ISO-4017-Detail.webp) M4 Hex Head Bolt (GB/T 5782 / ISO 4014) are specified by thread size, length and head dimensions. The M4 row from the standard is reproduced below, followed by the drill sizes, spanner size and torque values used when installing this size. ## M4 Dimensional Row (GB/T 5782 / ISO 4014) | Size | Pitch (mm) | Nominal diameter d (mm) | Length L (mm) | Width across flats s (mm) | Width across corners e (mm) | Head height k (mm) | | --- | --- | --- | --- | --- | --- | --- | | M4 | 0.7 | 4 | 25 | 7.0 | 7.66 | 2.8 | ## Spanner & Drive for M4 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) M4 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) have a width across flats of 7.0 mm — fit a 7.0 mm open-ended spanner or socket. Prefer a 6-point socket over a 12-point: it loads the corners of the 7.0 mm hex far less, which matters on plated heads and on anything that will be re-used. Set preload with a torque wrench rather than by arm. ## Hole Sizes for M4 | Coarse-thread pitch (ISO 724) | 0.7 mm | | --- | --- | | Through-hole / clearance (ISO 273 medium) | 4.5 mm | | Tapping drill, coarse thread | 3.3 mm | ## Tightening Torque for M4 | Class 8.8 (dry, ~µ 0.125) | ≈ 2.9 Nm | | --- | --- | | Class 10.9 (dry, ~µ 0.125) | ≈ Nm | | Class 12.9 (dry, ~µ 0.125) | ≈ 5 Nm | Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class. ## Proof Load & Strength for M4 | Tensile stress area As (ISO 724) | 8.8 mm² | | --- | --- | | Proof load, class 8.8 | 5.1 kN | | Proof load, class 12.9 | 8.5 kN | | Min. ultimate tensile load, class 8.8 | 7 kN | Proof load = tensile stress area × the proof stress Sp of the class, per ISO 898-1 — Sp is a lower figure than the yield stress Rp0.2 and the two are not interchangeable. The stress area is computed from this size's own diameter and pitch, so a fine-pitch designation gives the fine-pitch figure. Design the joint so the working preload stays below the proof load of the class selected. ## M4 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) Weight A steel M4 hex head bolt at the listed 25 mm length weighs approximately 3.4 g each — about 3.4 kg per 1,000 pieces. Stainless A2/A4 weighs roughly the same (density 7.9–8.0 g/cm³). Actual weight varies slightly with head form, thread and finish; use this figure for freight estimation only. ## Mating Parts for M4 For M4, pair with a M4 hex nut (ISO 4032 / DIN 934) and, where used, a M4 flat washer (ISO 7089 / DIN 125A) under the head and under the nut. ## When to Step Up or Down from M4 When the joint preload approaches the proof load of M4 class 8.8, step up to M5 class 8.8 (or move to M4 class 10.9). When the joint is over-specified, M3 often saves weight and cost without losing the safety margin. Custom manufacturing · Made to drawing ## Need hex head bolt in a size this table does not list? This page covers M4 hex head bolt. Head form and drive can be specified to the assembly rather than to a standard: a larger bearing face, a security drive, or a socket sized for the tool already on the bench. Made by cold heading or hot forging. Minimum order from 2,000 pieces; samples within 7 days of drawing approval. [Custom bolt manufacturing](https://engineeringhardware.com/custom/bolts/)[Send a drawing](https://engineeringhardware.com/custom/bolts/#rfq) ## Technical Drawing Dimensioned line drawing of M4 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) to GB/T 5782 / ISO 4014. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Pitch (mm):** 0.7 - **Nominal diameter d (mm):** 4 - **Length L (mm):** 25 - **Width across flats s (mm):** 7.0 - **Width across corners e (mm):** 7.66 - **Head height k (mm):** 2.8 ## Dimensions & Specifications (GB/T 5782 / ISO 4014) | Size | Pitch (mm) | Nominal diameter d (mm) | Length L (mm) | Width across flats s (mm) | Width across corners e (mm) | Head height k (mm) | | --- | --- | --- | --- | --- | --- | --- | | M3 | 0.5 | 3 | 20 | 5.5 | 6.01 | 2.0 | | M4 | 0.7 | 4 | 25 | 7.0 | 7.66 | 2.8 | | M5 | 0.8 | 5 | 30 | 8.0 | 8.79 | 3.5 | | M6 | 1.0 | 6 | 40 | 10.0 | 11.05 | 4.0 | | M8 | 1.25 | 8 | 50 | 13.0 | 14.38 | 5.3 | | M10 | 1.5 | 10 | 60 | 16.0 | 17.77 | 6.4 | | M12 | 1.75 | 12 | 80 | 18.0 | 20.03 | 7.5 | | M14 | 2.0 | 14 | 80 | 21.0 | 23.36 | 8.8 | | M16 | 2.0 | 16 | 100 | 24.0 | 26.75 | 10.0 | | M18 | 2.5 | 18 | 100 | 27.0 | 30.14 | 11.5 | | M20 | 2.5 | 20 | 120 | 30.0 | 33.53 | 12.5 | | M24 | 3.0 | 24 | 150 | 36.0 | 39.98 | 15.0 | | M30 | 3.5 | 30 | 180 | 46.0 | 50.85 | 18.7 | | M36 | 4.0 | 36 | 200 | 55.0 | 60.79 | 22.5 | ## Materials & Grades Select a material class to see the grades we supply it in. Each designation is listed with its ISO/EN, AISI/SAE, JIS and GB equivalents. Stainless Steel38 Carbon Steel66 Alloy Steel41 Bearing Steel5 Spring Steel25 Aluminum and Aluminum Alloys21 Brass17 Bronze11 Copper8 Titanium and Titanium Alloys18 Nickel and Nickel Alloys22 Iron-Nickel and High-Temperature Alloys10 Tool Steel and Specialty Hardened Steel9 Structural and Construction Steel9 ### Stainless Steel #### Austenitic Stainless Steel - A1 AISI 303 · SAE 303 · SUS303 · EN 1.4305 · X8CrNiS18-9 - A2 AISI 304 · SAE 304 · SUS304 · EN 1.4301 · X5CrNi18-10 · 06Cr19Ni10 - 304L AISI 304L · SUS304L · EN 1.4307 · X2CrNi18-9 · 022Cr19Ni10 - 302 AISI 302 · SUS302 · EN 1.4310 - 305 AISI 305 · SUS305 · EN 1.4303 - A4 AISI 316 · SAE 316 · SUS316 · EN 1.4401 · X5CrNiMo17-12-2 · 06Cr17Ni12Mo2 - 316L AISI 316L · SUS316L · EN 1.4404 · X2CrNiMo17-12-2 · 022Cr17Ni12Mo2 - 321 AISI 321 · SUS321 · EN 1.4541 · X6CrNiTi18-10 - 310 / 310S AISI 310 · AISI 310S · SUS310S · EN 1.4845 - 302HQ AISI 302HQ - A3 - A5 - 347 AISI 347 · SUS347 · EN 1.4550 · X6CrNiNb18-10 - 309 / 309S AISI 309 · AISI 309S · SUS309S #### Martensitic Stainless Steel - AISI 410 SUS410 · EN 1.4006 · X12Cr13 · 12Cr13 - AISI 420 SUS420J1 · SUS420J2 · EN 1.4021 · EN 1.4028 · 20Cr13 · 30Cr13 - AISI 431 SUS431 · EN 1.4057 · X17CrNi16-2 - C1 - C3 - C4 - AISI 440A - AISI 440B - AISI 440C SUS440C · EN 1.4125 #### Ferritic Stainless Steel - AISI 430 SUS430 · EN 1.4016 · X6Cr17 · 10Cr17 - F1 - AISI 434 - AISI 444 #### Precipitation-Hardening Stainless Steel - 17-4 PH AISI 630 · UNS S17400 · SUS630 · EN 1.4542 · X5CrNiCuNb16-4 - 15-5 PH UNS S15500 - 17-7 PH UNS S17700 #### Duplex and Super Duplex Stainless Steel - Duplex 2205 UNS S31803 · UNS S32205 · EN 1.4462 - Super Duplex 2507 UNS S32750 · EN 1.4410 - D2 - D4 - D6 - D8 - Lean Duplex 2101 UNS S32101 - Super Duplex S32760 UNS S32760 · EN 1.4501 ### Carbon Steel #### Low-Carbon Steel - SAE 1006 - SAE 1008 - SAE 1010 - SAE 1018 - SAE 1020 - Q195 - Q235 - SAE 1012 - SAE 1015 - Q215 - ML08 - ML08Al - ML10 - ML15 - ML20 - SWRCH6A - SWRCH8A - SWRCH10A - SWRCH12A - SWRCH15A - SWRCH18A #### Medium-Carbon Steel - SAE 1035 - SAE 1045 - S45C - C45 - SAE 1030 - SAE 1040 - SAE 1050 - 30 - 35 - 40 - 45 - 50 - S35C - S40C - S50C - C35 - C40 #### High-Carbon Steel - SAE 1060 - SAE 1070 - 65Mn - SAE 1065 - SAE 1075 - SAE 1080 - SAE 1085 - SAE 1090 - SAE 1095 - 60 - 65 - 70 - 75 - 80 - 85 #### Cold-Heading Steel - SWRCH22A - 10B21 - SWRCH22K - SWRCH25K - SWRCH30K - SWRCH35K - SWRCH40K - ML20Mn - ML25 - ML30 - ML35 - ML40 - 15B25 ### Alloy Steel #### Chromium Steel - 40Cr - 45Cr - AISI 5140 - SAE 5140 - AISI 5120 - SAE 5120 - SCr420 - SCr440 #### Chromium-Molybdenum Steel - 35CrMo - 42CrMo - AISI 4140 - SCM435 - SCM440 - 42CrMo4 - 30CrMo - AISI 4130 - SAE 4130 - SAE 4140 - AISI 4142 - AISI 4145 - SCM415 - SCM420 - SCM445 - EN 1.7220 - EN 1.7225 - 25CrMo4 - 34CrMo4 #### Nickel-Chromium-Molybdenum Steel - AISI 4340 - SAE 4340 - 40CrNiMo - SNCM439 - EN 1.6511 - 36CrNiMo4 #### Boron Alloy Steel - 10B22 - 10B21 - 15B21 - 15B25 - 20MnTiB - 20Mn2B - 35VB - 40MnB ### Bearing Steel #### Bearing Steel - GCr15 - AISI 52100 SAE 52100 · UNS G52986 - SUJ2 - 100Cr6 EN 1.3505 - GCr15SiMn ### Spring Steel #### Carbon Spring Steel - SAE 1065 - SAE 1070 - SAE 1075 - SAE 1080 - SAE 1095 - 65 - 70 - 75 - 80 - 65Mn #### Silicon-Manganese Spring Steel - 60Si2Mn - 60Si2MnA - SUP6 - SUP7 #### Chromium-Vanadium Spring Steel - 50CrVA - SAE 6150 - AISI 6150 - SUP10 #### Stainless Spring Steel - AISI 301 - SUS301 - EN 1.4310 - AISI 302 - AISI 304 - AISI 316 - 17-7 PH ### Aluminum and Aluminum Alloys #### Commercially Pure Aluminum - 1050 - 1060 - 1070 - 1100 #### 2xxx Series Aluminum - 2024 - 2011 - 2014 - 2017 #### 5xxx Series Aluminum - 5052 - 5083 - 5754 #### 6xxx Series Aluminum - 6061 - 6061-T6 - 6063 - 6082 - 6082-T6 #### 7xxx Series Aluminum - 7075 - 7075-T6 - 7005 - 7050 - 7075-T73 ### Brass #### Free-Cutting Brass - C36000 - H62 - HPb59-1 - C3601 - C3602 - C3604 - CuZn36Pb3 - CuZn39Pb3 - EN CW614N - EN CW617N - H65 #### Lead-Free Brass - C69300 - C27450 - CW510L - CW511L #### Naval Brass - C46400 - CuZn39Sn1 ### Bronze #### Silicon Bronze - C65500 - C65100 - C65600 #### Phosphor Bronze - C51000 - C52100 - CuSn6 - CuSn8 #### Aluminum Bronze - C95400 - C95500 - C63000 - CuAl10Ni5Fe4 ### Copper #### Copper - C11000 - T2 - C10100 - C10200 - C12200 - T1 - TU1 - TU2 ### Titanium and Titanium Alloys #### Commercially Pure Titanium - Grade 2 - Grade 1 - Grade 3 - Grade 4 - TA1 - TA2 - TA3 #### Alpha-Beta Titanium Alloys - Grade 5 - Ti-6Al-4V - TC4 - UNS R56400 #### Low-Interstitial Grade - Grade 23 - Ti-6Al-4V ELI - UNS R56407 #### Other Titanium Fastener Alloys - Ti-6Al-6V-2Sn - Ti-6Al-2Sn-4Zr-2Mo - Beta-C titanium - Ti-10V-2Fe-3Al ### Nickel and Nickel Alloys #### Commercially Pure Nickel - Nickel 200 - UNS N02200 - Nickel 201 - UNS N02201 #### Inconel Alloys - Inconel 625 UNS N06625 - Inconel 718 UNS N07718 - Inconel 600 UNS N06600 - Inconel 601 UNS N06601 - Inconel 686 UNS N06686 - Inconel X-750 UNS N07750 #### Monel Alloys - Monel 400 UNS N04400 - Monel K-500 UNS N05500 #### Hastelloy Alloys - Hastelloy C-276 UNS N10276 - Hastelloy C-22 UNS N06022 - Hastelloy B-2 UNS N10665 - Hastelloy B-3 UNS N10675 - Hastelloy X UNS N06002 #### Other Nickel Alloys - Alloy 20 UNS N08020 - Alloy 625 - Alloy 718 - Alloy 825 UNS N08825 - Alloy 925 UNS N09925 ### Iron-Nickel and High-Temperature Alloys #### A286 - A-286 - UNS S66286 - EN 1.4980 #### Invar - Invar 36 - Alloy 36 - UNS K93600 - FeNi36 #### Alloy 42 - Alloy 42 - UNS K94100 - FeNi42 ### Tool Steel and Specialty Hardened Steel #### Tool Steel and Specialty Hardened Steel - AISI D2 - AISI H13 - SKD11 - Cr12MoV - AISI O1 - AISI A2 - AISI S7 - SKD61 - 9CrSi ### Structural and Construction Steel #### Structural and Construction Steel - ASTM A36 - Q235B - Q355B - S355JR - Q235C - Q355C - S235JR - S275JR - S355J2 ## Applications & Industries for M4 Hex Head Bolt Where Hex Head Bolt are used, and what decides the specification in each case. Stocked from M3 to M36. ### Industries that specify Hex Head Bolt - **Steel fabrication:** Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site. - **Energy & infrastructure:** Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints. - **Maintenance & MRO:** Stocked replacements matched to an existing property class, thread and finish. - **Food, pharma & cleanroom:** Stainless assemblies that are washed down, where the finish matters as much as the strength. - **Machine building & OEM:** The default fastener on production equipment: covers, brackets, motor mounts and sub-assemblies tightened to a specified torque. - **Automotive & transport:** Chassis, driveline and body fixings that see vibration and are assembled to a controlled preload. ### Typical applications - clamping two machined faces to a calculated preload - bolting brackets, motors and gearboxes to a frame - assemblies that are dismantled for service and re-torqued - joints where the property class is stated on the drawing ### Service conditions to specify against - **Marine and coastal:** Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit. - **High load:** Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel. - **Torque and preload:** The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together. ### Where to use something else - Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material. Need help matching Hex Head Bolt to your application? Send the assembly, the load and the environment with your enquiry and we will specify the size, material and finish against them. 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 clearance and tapping drill suit M4? Use a 4.5 mm clearance hole (ISO 273 medium) for through-fixing, or a 3.3 mm tapping drill for a coarse M4 thread. ### Is M4 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) suitable for electronics and small mechanisms? M4 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) is in the micro range and is widely used in electronics, instrument enclosures and small precision mechanisms. Watch the over-torque margin — micro joints strip easily. ### What's the typical proof load behavior of M4 class 8.8? Micro-thread joints are sensitive to plastic deformation in the first turn under load — use a torque-limiting driver and check the bearing surface deformation on softer mating materials. ### What spanner size fits M4 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007)? The width across flats for M4 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) is 7.0 mm, so a 7.0 mm spanner or 6-point socket fits. ### How do I request a quotation? Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day. ## Related Pages [View the full Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) page](https://engineeringhardware.com/fastener/cad-svg-007-hexbolt/) ### More Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 007) Guides