Technically reviewed by Vincent, Founder at HEXVARO
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Sourcing these sizes? ISO 7380 button head screws Socket head screw supplier
ISO 7380-1 button head dimensions (mm)
Head diameter dk and head height k are given as maximum and minimum values. Socket s is the nominal hex key size. Socket depth t is the minimum key engagement, which is much shallower than on a cap screw. Values are from published DIN EN ISO 7380-1 tables.
| Size | Pitch P | Head dia. dk max | dk min | Head height k max | k min | Hex key s | Socket depth t min | Inquiry |
|---|---|---|---|---|---|---|---|---|
| M3 | 0.5 | 5.7 | 5.4 | 1.65 | 1.4 | 2 | 1.04 | Quote this size |
| M4 | 0.7 | 7.6 | 7.24 | 2.2 | 1.95 | 2.5 | 1.3 | Quote this size |
| M5 | 0.8 | 9.5 | 9.14 | 2.75 | 2.5 | 3 | 1.56 | Quote this size |
| M6 | 1.0 | 10.5 | 10.07 | 3.3 | 3.0 | 4 | 2.08 | Quote this size |
| M8 | 1.25 | 14 | 13.57 | 4.4 | 4.1 | 5 | 2.6 | Quote this size |
| M10 | 1.5 | 17.5 | 17.07 | 5.5 | 5.2 | 6 | 3.12 | Quote this size |
| M12 | 1.75 | 21 | 20.48 | 6.6 | 6.24 | 8 | 4.16 | Quote this size |
| M16 | 2.0 | 28 | 27.48 | 8.8 | 8.44 | 10 | 5.2 | Quote this size |
Hex key sizes: button head vs socket head cap screw
The most common ordering and assembly mistake is assuming a button head takes the same key as a DIN 912 / ISO 4762 cap screw. It does not. For every size from M3 to M16 the button head key is one step smaller, so tool kits and automatic drivers must be set up separately.
| Size | ISO 7380-1 button head key (mm) | DIN 912 / ISO 4762 cap screw key (mm) | Inquiry |
|---|---|---|---|
| M3 | 2 | 2.5 | Quote this size |
| M4 | 2.5 | 3 | Quote this size |
| M5 | 3 | 4 | Quote this size |
| M6 | 4 | 5 | Quote this size |
| M8 | 5 | 6 | Quote this size |
| M10 | 6 | 8 | Quote this size |
| M12 | 8 | 10 | Quote this size |
| M16 | 10 | 14 | Quote this size |
Approximate weight per 1000 pcs (kg)
Weights are for plain steel (density 7.85 kg/dm³) from the published ISO 7380-1 mass table. Use them to estimate carton count and freight for mixed orders. Zinc or zinc flake adds very little; stainless A2 / A4 is about the same weight.
| Size × length | kg / 1000 | Size × length | kg / 1000 | Inquiry |
|---|---|---|---|---|
| M3 × 8 | 0.50 | M3 × 12 | 0.67 | Quote this size |
| M4 × 10 | 1.15 | M4 × 16 | 1.57 | Quote this size |
| M5 × 12 | 2.26 | M5 × 20 | 3.19 | Quote this size |
| M6 × 16 | 3.92 | M6 × 25 | 5.42 | Quote this size |
| M8 × 20 | 9.07 | M8 × 30 | 12.12 | Quote this size |
| M10 × 25 | 18.1 | M10 × 40 | 25.4 | Quote this size |
| M12 × 30 | 31.1 | M12 × 50 | 45.2 | Quote this size |
| M16 × 40 | 76.6 | M16 × 60 | 102.6 | Quote this size |
Common lengths
The published mass table covers these length ranges: M3 5–30 mm, M4 6–50 mm, M5 6–60 mm, M6 6–100 mm, M8 10–100 mm, M10 12–120 mm, M12 16–120 mm and M16 20–120 mm. Short lengths such as M6 × 10 to M6 × 30 and M8 × 12 to M8 × 30 are the fast movers in distribution. Long button head screws are less common and more likely to be made to order.
Lengths are measured from under the head to the tip. State full or partial thread if your drawing controls it.
Why button heads are marked 010.9, not 10.9
ISO 7380-1 screws are classed as having reduced loadability. The low head and shallow socket mean the head, not the thread, sets the limit. The standard assumes the head carries about 80 % of the thread's load capacity for all sizes and property classes.
To show this, the property class is marked with a leading zero, for example 010.9 instead of 10.9. A button head screw marked 010.9 is made from the same steel and heat treatment as a 10.9 cap screw, but it must not be used where a full 10.9 clamp load is designed in. If a joint needs full strength, specify DIN 912 / ISO 4762 instead.
- Steel 010.9 is the usual class for black or zinc flake button head screws.
- The standard covers both steel and stainless steel versions; A2 and A4 are the common stainless choices.
- Product grade is A (the tighter tolerance grade).
ISO 7380-1 vs ISO 7380-2 and older names
ISO 7380 is split into parts. Part 1 is the plain button head; part 2 has a flange (collar) under the head, which spreads load on thin sheet and slotted holes. The current part 1 edition is ISO 7380-1:2022. Many buyers still write simply ISO 7380; if you do not want flanged screws, write ISO 7380-1.
ISO 7380-1 superseded the former DIN 7380 data, which still appears on older drawings. Check head diameter and key size before treating any other button head standard as equivalent.
Mistakes to avoid
- Using the cap screw torque table. Button heads need lower tightening torque because of the reduced head strength and the small socket.
- Electroplating 010.9 or harder screws without a hydrogen embrittlement plan. Specify baking, or choose zinc flake or black oxide.
- Ordering without stating part 1 or part 2 when the drawing shows a flange.
- Mixing button head and cap screw keys on one assembly line without clear labelling.
How to specify button head screws in your RFQ
- Standard: ISO 7380-1 (plain) or ISO 7380-2 (with flange).
- Size × length, e.g. M6 × 16, and quantity per size.
- Property class for steel with the reduced-loadability mark, e.g. 010.9, or stainless A2-70 / A4-80.
- Finish with a full designation: black oxide, zinc plated (with baking for 010.9 and above), zinc flake, or plain stainless.
- Packaging (boxes or bulk cartons), labelling and any inspection certificate such as EN 10204 3.1.
Order these sizes from HEXVARO
Send your size list with grade, finish and quantity — we reply within 2 working hours with price, lead time and shipping terms.
- Reply: within 2 working hours
- MOQ: 500 pcs per specification
- Lead time: 10–15 days stock items
- Payment: T/T · L/C · PayPal
- Shipping ports: Tianjin · Ningbo · Shanghai · Shenzhen
- Incoterms: EXW · FOB · CFR · CIF · DAP
- Experience: Founder with 10+ years in the fastener industry
Frequently asked questions
What hex key fits an M6 button head screw?
A 4 mm hex key fits an M6 ISO 7380 button head screw. That is one size smaller than the 5 mm key for an M6 DIN 912 cap screw.
What size Allen key for an M8 button head?
5 mm. An M8 DIN 912 socket head cap screw takes 6 mm, so do not use the same key.
Are button head screws as strong as socket head cap screws?
No. ISO 7380-1 classes them as reduced loadability: the head is assumed to carry about 80 % of the thread's load. That is why a steel button head in class 10.9 is marked 010.9. Use DIN 912 / ISO 4762 where full clamp load is needed.
What does 010.9 mean on a button head screw?
It means property class 10.9 steel with reduced loadability. The leading zero warns that the head design limits the load the screw can carry.
Is ISO 7380 the same as ISO 7380-1?
ISO 7380 has separate parts. Part 1 covers button heads without a flange and part 2 covers button heads with a flange. Most buyers mean ISO 7380-1.
What is the MOQ for button head screws?
Reference MOQ is 500 pcs per specification. Stock sizes typically ship in 10–15 days and made-to-order sizes in 25–30 days, subject to quotation. We reply to every RFQ within 2 working hours.
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