Dimensional and assembly data for M14 Hex Head Bolt to GB/T 5782 / ISO 4014. Includes head size and width across flats, clearance-hole and tapping-drill diameters, tightening torque per property class, and the sizes to step up or down to when the joint requires it.
M14 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) |
|---|---|---|---|---|---|---|
| M14 | 2.0 | 14 | 80 | 21.0 | 23.36 | 8.8 |
Spanner & Drive for M14 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 002)
M14 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 002) have a width across flats of 21.0 mm — fit a 21.0 mm open-ended spanner or socket. A 6-point socket grips all six flats of the 21.0 mm hex and is what to reach for once a fastener has been on and off a few times; a 12-point ring spanner starts rounding a worn head. For repeatable preload, torque rather than feel.
Hole Sizes for M14
| Coarse-thread pitch (ISO 724) | 2 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 15.5 mm |
| Tapping drill, coarse thread | 12 mm |
Tightening Torque for M14
| Class 8.8 (dry, ~µ 0.125) | ≈ 134 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 197 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 231 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 M14
| Tensile stress area As (ISO 724) | 115 mm² |
|---|---|
| Proof load, class 8.8 | 67 kN |
| Proof load, class 10.9 | 96 kN |
| Proof load, class 12.9 | 112 kN |
| Min. ultimate tensile load, class 8.8 | 92 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.
M14 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 002) Weight
A steel M14 hex head bolt at the listed 80 mm length weighs approximately 123 g each — about 123 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.
Installation Tips for M14 Hex Head Bolt — GB/T 5782 / ISO 4014 (Series 002)
- Use a 6-point socket where access allows — 12-point sockets are more prone to rounding the corners on smaller sizes.
- On flanged or serrated variants, do NOT add a separate flat washer — the flange already spreads the load and the washer can defeat the locking serrations.
Mating Parts for M14
For M14, pair with a M14 hex nut (ISO 4032 / DIN 934) and, where used, a M14 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
Custom manufacturing · Made to drawing
Need hex head bolt in a size this table does not list?
This page covers M14 hex head bolt. Lengths and thread lengths outside the standard table are the commonest request, followed by a drive the standard does not offer and a head marked with your own part number. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
