DIN 571 Hex Head Wood Screws (Lag Screws)
DIN 571 hexagon head wood screws — the metric lag screw — in M4 to M20, with the full collected per-size geometry table (shank and thread diameters, head height, width across flats, minimum head-corner diameter) and the collected length ladder from 16 to 200 mm with the per-size weight of every stocked length.
Last updated: 2026-11
Specifications
DIN 571 is the metric lag screw: a coarse, tapered-point wood thread under a hex head you drive with a socket or spanner instead of a screwdriver bit. That one change of drive is the whole point at structural scale — a lag screw takes installation torque that would strip a slotted or recessed head long before the thread bottomed in the joist, which is why DIN 571 is the default fastener for heavy timber connections, roof trusses, carport beams, play structures and any wood-to-wood or wood-to-metal joint assembled on site. The collected specification table runs the full M4 to M20 series and tabulates what the installer and the die shop both need: the thread diameter tolerances (max/min), the washers-face diameter under the head, the head height k, and the width across flats s — 7 mm at M4 growing to 30 mm at M20 — together with the minimum across-corners dimension e that keeps a socket from camming off. Two practical notes when specifying: pilot-hole drilling rules matter more here than on any machine screw, because the wood thread cuts its own mate and an oversized pilot strips the grip; and where the joint also carries pull-out through a metal fitting, pair the screw with the matching washer rather than bearing the hex head directly on the fitting. For the countersunk wood-screw line, see the DIN 97, DIN 95 and DIN 96 pages on this site.
| Standard | DIN 571 — hexagon head wood screws (metric lag screws) |
|---|---|
| Series | M4, M5, M6, (M7), M8, M10, M12, M16, M20 — parenthesized sizes are non-preferred |
| Drive | Hex head, driven by wrench or socket; width across flats 7–30 mm per size (tabulated) |
| Tabulated geometry | Per size: thread dia d max/min, head-face dia da max, head height k nominal/max/min, width across flats s max/min, across-corners e min |
| Lengths | Collected ladder 16–200 mm (13 steps) with per-size weight; every stocked length carries its own l min/max tolerance band — see the length table on this page |
| Materials / finish | Not tabulated by the collected specification — per RFQ (steel, galvanized or stainless typical for the market) |
| Nominal thread | d s max (= nominal) (mm) | d s min (mm) | d a max (mm) | k nominal (mm) | k max (mm) | k min (mm) | s max (= nominal) (mm) | s min (mm) | e min (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M4 | 4 | 3.52 | 5 | 2.8 | 3.1 | 2.5 | 7 | 6.64 | 7.5 |
| M5 | 5 | 4.52 | 6 | 3.5 | 3.88 | 3.13 | 8 | 7.64 | 8.63 |
| M6 | 6 | 5.52 | 7.2 | 4 | 4.38 | 3.63 | 10 | 9.64 | 10.89 |
| (M7) | 7 | 6.42 | 8.2 | 5 | 5.38 | 4.63 | 12 | 11.57 | 13.07 |
| M8 | 8 | 7.42 | 10.2 | 5.5 | 5.88 | 5.13 | 13 | 12.57 | 14.2 |
| M10 | 10 | 9.42 | 12.2 | 7 | 7.45 | 6.55 | 17 | 16.57 | 18.72 |
| M12 | 12 | 11.3 | 15.2 | 8 | 8.45 | 7.55 | 19 | 18.48 | 20.88 |
| M16 | 16 | 15.3 | 19.2 | 10 | 10.45 | 9.55 | 24 | 23.16 | 26.17 |
| M20 | 20 | 19.3 | 24.4 | 13 | 13.9 | 12.1 | 30 | 29.16 | 32.95 |
| Length l nominal (mm) | l min. (mm) | l max. (mm) | Weight kg/1000 pcs — M4 | Weight kg/1000 pcs — M5 | Weight kg/1000 pcs — M6 | Weight kg/1000 pcs — (M7) | Weight kg/1000 pcs — M8 | Weight kg/1000 pcs — M10 | Weight kg/1000 pcs — M12 | Weight kg/1000 pcs — M16 | Weight kg/1000 pcs — M20 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 16 | 15,1 | 16,9 | 1,71 | 292 | |||||||
| 20 | 18,95 | 21,05 | 2,01 | 3,42 | 5,02 | ||||||
| 25 | 23,95 | 26,05 | 2,41 | 4,02 | 5,82 | 11,5 | |||||
| 30 | 28,95 | 31,05 | 2,81 | 4,62 | 6,62 | 12,9 | 23,6 | ||||
| 35 | 33,75 | 36,25 | 3,11 | 5,12 | 7,42 | 14,2 | 25,8 | 36,2 | |||
| 40 | 38,75 | 41,25 | 3,51 | 5,82 | 8,22 | 15,6 | 28 | 39,2 | |||
| 45 | 43,75 | 46,25 | 8,94 | 16,9 | 30 | 42,1 | |||||
| 50 | 48,75 | 51,25 | 9,64 | 18,2 | 32,1 | 45,4 | 84,1 | ||||
| 55 | 53,5 | 56,5 | 10,5 | 19,6 | 34,3 | 48,6 | 89,7 | ||||
| 60 | 58,5 | 61,5 | 11,2 | 20,9 | 36,5 | 51,8 | 94,9 | 165 | |||
| 65 | 63,5 | 66,5 | 22,2 | 38,5 | 54,7 | 99,5 | 174 | ||||
| 70 | 68,5 | 71,5 | 23,6 | 40,7 | 57,8 | 107 | 182 | ||||
| 75 | 73,5 | 76,5 | 25 | 42,9 | 61 | 112 | 192 | ||||
| 80 | 78,5 | 81,5 | 26,5 | 45,2 | 64,5 | 118 | 201 | ||||
| 90 | 88,25 | 91,75 | 29,4 | 49,9 | 71 | 130 | 220 | ||||
| 100 | 98,25 | 101,75 | 32 | 54 | 77,1 | 141 | 238 | ||||
| 110 | 108,25 | 111,75 | 83,4 | 152 | 253 | ||||||
| 120 | 118,25 | 121,75 | 89,5 | 163 | 275 | ||||||
| 130 | 128 | 132 | 175 | 293 | |||||||
| 140 | 138 | 142 | 187 | 317 | |||||||
| 150 | 148 | 152 | 198 | 328 | |||||||
| 160 | 158 | 162 | 209 | 348 | |||||||
| 170 | 168 | 172 | 366 | ||||||||
| 180 | 178 | 182 | 385 | ||||||||
| 190 | 187,7 | 192,3 | 404 | ||||||||
| 200 | 197,7 | 202,3 | 421 |
- Row 1 (16): The M5 cell at l = 16 prints 292 with no decimal comma. The M5 weight progression (3,42 at l = 20, rising 0,60 per 5 mm) extrapolates to 2,92 at l = 16 — the source almost certainly dropped the decimal comma. The cell is reproduced verbatim as printed and not normalized; do not quote it as a shipping weight without verification.
- Row 10 (60): Column alignment note (batch-level, anchored here): the nine weight columns align to the nine thread sizes of the source header; this was verified against the rendered grid (rowspan/colspan expanded), the rendered-page screenshot, and the monotone per-size progressions (e.g. M4 rises 0,08 per mm of length, M20 rises ~2,3 per mm), not inferred from the flattened markup alone.
Materials
- Material, strength class and finish specified per RFQ — the collected specification table covers geometry only
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (DIN 571 Hex Head Wood Screws (Lag Screws)) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
What pilot hole should I drill for a DIN 571 lag screw?
The wood thread cuts its own mate, so the pilot governs the grip. Standard practice is a pilot matched to the screw core diameter in the threaded zone and to the shank diameter where the unthreaded shank passes through, drilled deeper than the screw length to relieve end pressure in dense species. The geometry you need to size it — core and thread diameters per size — is in the collected table. Torque rather than feel should stop the drive; a lag screw driven to a stripped socket has already lost its clamp.
What should an RFQ for DIN 571 wood screws state?
The designation and thread size (M4–M20), length under the head, material and finish (zinc-plated, hot-dip galvanized or stainless per the exposure), any certificate requirement, and quantity per size. Where the screws pull through steel fittings, add the mating washer dimension. Head height and width-across-flats tolerances are in the specification table on this page; commercial terms follow the quotation.
What is the MOQ and lead time for these screws?
Minimum order quantity is 10,000 pieces per item. Stocked sizes ship in 3–7 days; non-stock diameters, lengths or finishes are quoted with a confirmed schedule. Common sizes in this designation are widely stocked — confirm the exact schedule against quantity and size mix at quotation.
Related knowledge
- Thread-Forming vs Thread-Cutting vs Thread-Rolling Self-Tapping Screws: What the Evidence Settles on Base Material
- Screw Family Selection by Base Material: Wood, Machine and Self-Tapping Threads, Engagement and Coating
- Hex Bolts vs Socket Head Cap Screws: What the Evidence Settles on Strength, Clearance and Cost
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support