M4 is one of the standard coarse-thread sizes for low head socket cap screws under DIN 7984. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M4 Dimensional Row (DIN 7984)
| Size | Pitch P (mm) | b (mm) | Head diameter dk (mm) | da (mm) | ds_min (mm) | e (mm) | Head height k (mm) | r (mm) | Hex socket s (mm) | t (mm) | v (mm) | dw (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M4 | 0.7 | 14 | 7.0 | 4.7 | 3.82 | 2.87 | 2.8 | 0.2 | 2.5 | 2.3 | 0.4 | 6.2 | 6~25 | DIN 7984 |
Spanner & Drive for M4 Low Head Socket Cap Screws
The hex socket for M4 Low Head Socket Cap Screws is shown in the spec table — use the matching Allen / hex key (an ISO 2936 hex key set covers the full range). A T-handle key gives the most feel when you are judging preload by hand; anything repeated across a batch wants a torque-controlled driver instead.
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
This is a reduced-height head. The head, not the thread, limits what the screw will carry — ISO 7380-1 caps a button head at roughly 80% of the thread's capacity — so the thread's proof load overstates the assembly. Size the joint on the head, or use a cap screw where the full class strength is needed.
M4 Low Head Socket Cap Screws Weight
A steel M4 low head socket cap screws at the listed 625 mm length weighs approximately 189 g each — about 189 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 M4 Low Head Socket Cap Screws
- Use a quality Allen key fully seated in the socket — partial engagement is the most common cause of stripped sockets at this size.
- For countersunk and button-head variants, chamfer the through-hole to seat the head flush without preloading the head/shank fillet.
- At M4 the joint is sensitive to over-torque — use a torque-limiting driver and check the head doesn't bury into a softer counterpart.
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.
Custom manufacturing · Made to drawing
Need low head socket cap screws in a size this table does not list?
This page covers M4 low head socket cap screws. Material and finish are usually what drives a special — a grade the standard part is not stocked in, or a coating chosen against a salt-spray figure instead of a default. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
