M16 Hex Head Bolts with Reduced Shank are manufactured to ISO 4015 with a coarse thread pitch of 2 mm. This page lists the controlling dimensions for the M16 size — head geometry, width across flats, matching spanner size — together with the clearance hole, tapping drill and tightening torque used at assembly.
M16 Dimensional Row (ISO 4015)
| Size | Pitch P (mm) | b1 (mm) | b2 (mm) | c_max (mm) | d_a_max (mm) | d_s (mm) | d_w_min (mm) | Width across corners e (mm) | Head height k (mm) | k_max (mm) | k_min (mm) | k_w_min (mm) | r_min (mm) | Width across flats s (mm) | s_min (mm) | x_max (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M16 | 2 | 38 | 44 | 0.8 | 17.7 | 14.5 | 22 | 26.17 | 10 | 10.29 | 9.71 | 6.8 | 0.6 | 24 | 23.16 | 5 | 55~150 | ISO 4015 |
Spanner & Drive for M16 Hex Head Bolts with Reduced Shank
M16 Hex Head Bolts with Reduced Shank have a width across flats of 24 mm — fit a 24 mm open-ended spanner or socket. In tight access a 6-point socket on the 24 mm flats gives the most engagement per degree of swing. Where the joint is torqued to a figure, a click wrench is the only way to reproduce it across a batch.
Hole Sizes for M16
| Coarse-thread pitch (ISO 724) | 2 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 17.5 mm |
| Tapping drill, coarse thread | 14 mm |
Tightening Torque for M16
| Class 8.8 (dry, ~µ 0.125) | ≈ 209 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 306 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 358 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 M16
| Tensile stress area As (ISO 724) | 157 mm² |
|---|---|
| Proof load, class 8.8 | 91 kN |
| Proof load, class 10.9 | 130 kN |
| Proof load, class 12.9 | 152 kN |
| Min. ultimate tensile load, class 8.8 | 125 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.
M16 Hex Head Bolts with Reduced Shank Weight
A steel M16 hex head bolts with reduced shank at the listed 55,150 mm length weighs approximately 87,084 g each — about 87,084 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 M16
For M16, pair with a M16 hex nut (ISO 4032 / DIN 934) and, where used, a M16 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
When to Step Up or Down from M16
When the joint preload approaches the proof load of M16 class 8.8, step up to M20 class 8.8 (or move to M16 class 10.9). When the joint is over-specified, M12 often saves weight and cost without losing the safety margin.
Custom manufacturing · Made to drawing
Need hex head bolts with reduced shank in a size this table does not list?
This page covers M16 hex head bolts with reduced shank. 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.
