ISO 2904 Metric Trapezoidal Screw Threads
ISO 2904 basic dimensions for ISO metric trapezoidal screw threads — 70 Tr designations from Tr 8 × 1.5 to Tr 100 × 12 with pitch diameter d2 = D2, D4, d3, D1 and crest clearance ac per designation.
Last updated: 2026-11
Specifications
The trapezoidal (Tr) thread is the 30°-flank profile that power transmission screws use — lead screws, valve and gate stems, presses, machine-table traverses — and ISO 2904 is the standard that fixes its basic geometry: for each designation it tabulates the major diameter d (with the mating internal major D 4 = d + clearance), the pitch P, the pitch diameters d 2 = D 2 (shared by screw and nut), the external minor d 3 and internal minor D 1 of the design profile, and the crest clearance a c (0.15 for the 1.5 mm pitches, 0.25 up to P 6, 0.5 at P 7 and coarser). The collected ladder covers 70 designations from Tr 8 × 1.5 to Tr 100 × 12: smaller diameters carry fine and medium pitches (Tr 12 in 2 and 3), while from roughly Tr 30 upward each diameter pairs a 3–4 mm pitch with a coarse multi-start-friendly option (Tr 40 × 7, Tr 60 × 9, Tr 100 × 12). The governing standards around it are collected too: ISO 2901 (basic and design profiles), ISO 2902 (the full diameter/pitch plan), ISO 2903 (tolerance system) and ISO 2903-2 (limits of sizes). This site also carries the DIN 103 trapezoidal line — rod, hex nut and round nut — which is a separate designation from this ISO ladder; order by the standard your drawing calls. Thread-fit class, multi-start variants, lengths, materials and nut styles are not tabulated on the collected page — per RFQ.
| Standard | ISO 2904 — basic dimensions for ISO metric trapezoidal screw threads |
|---|---|
| Profile | Trapezoidal 30° included flank angle (profiles per ISO 2901; plan per ISO 2902) |
| Designation range | Tr 8 × 1.5 through Tr 100 × 12 — 70 diameter × pitch designations in the collected rows |
| Tabulated geometry | d (= D), P, d 2 = D 2, D 4, d 3, D 1, a c per designation (millimetres) |
| Crest clearance a c | 0.15 (P 1.5); 0.25 (P 2–6); 0.5 (P 7 and coarser) |
| Related standards | ISO 2901 (profiles), ISO 2902 (plan), ISO 2903 / ISO 2903-2 (tolerances and limits of sizes) |
| Not tabulated | Tolerance class, starts, lengths, materials, nut styles — per RFQ |
| Designation | d | P | d 2 = D 2 | D 4 | d 3 | D 1 | a c |
|---|---|---|---|---|---|---|---|
| Tr 8 × 1.5 | 8 | 1.5 | 7.250 | 8.300 | 6.200 | 6.500 | 0.15 |
| Tr 9 × 1.5 | 9 | 1.5 | 8.250 | 9.300 | 7.200 | 7.500 | 0.15 |
| Tr 9 × 2 | 9 | 2 | 8.000 | 9.500 | 6.500 | 7.000 | 0.25 |
| Tr 10 × 1.5 | 10 | 1.5 | 9.250 | 10.300 | 8.200 | 8.500 | 0.15 |
| Tr 10 × 2 | 10 | 2 | 9.000 | 10.500 | 7.500 | 8.000 | 0.25 |
| Tr 11 × 2 | 11 | 2 | 10.000 | 11.500 | 8.500 | 9.000 | 0.25 |
| Tr 11 × 3 | 11 | 3 | 9.500 | 11.500 | 7.500 | 8.000 | 0.25 |
| Tr 12 × 2 | 12 | 2 | 11.000 | 12.500 | 9.500 | 10.000 | 0.25 |
| Tr 12 × 3 | 12 | 3 | 10.500 | 12.500 | 8.500 | 9.000 | 0.25 |
| Tr 14 × 2 | 14 | 2 | 13.000 | 14.500 | 11.500 | 12.000 | 0.25 |
| Tr 14 × 3 | 14 | 3 | 12.500 | 14.500 | 10.500 | 11.000 | 0.25 |
| Tr 16 × 2 | 16 | 2 | 15.000 | 16.500 | 13.500 | 14.000 | 0.25 |
| Tr 16 × 3 | 16 | 3 | 14.500 | 16.500 | 12.500 | 13.000 | 0.25 |
| Tr 18 × 2 | 18 | 2 | 17.000 | 18.500 | 15.500 | 16.000 | 0.25 |
| Tr 18 × 4 | 18 | 4 | 16.000 | 18.500 | 13.500 | 14.000 | 0.25 |
| Tr 20 × 2 | 20 | 2 | 19.000 | 20.500 | 17.500 | 18.000 | 0.25 |
| Tr 20 × 4 | 20 | 4 | 18.000 | 20.500 | 15.500 | 16.000 | 0.25 |
| Tr 22 × 3 | 22 | 3 | 20.500 | 22.500 | 18.500 | 19.000 | 0.25 |
| Tr 22 × 5 | 22 | 5 | 19.500 | 22.500 | 16.500 | 17.000 | 0.25 |
| Tr 24 × 3 | 24 | 3 | 22.500 | 24.500 | 20.500 | 21.000 | 0.25 |
| Tr 24 × 5 | 24 | 5 | 21.500 | 24.500 | 18.500 | 19.000 | 0.25 |
| Tr 26 × 3 | 26 | 3 | 24.500 | 26.500 | 22.500 | 23.000 | 0.25 |
| Tr 26 × 5 | 26 | 5 | 23.500 | 26.500 | 20.500 | 21.000 | 0.25 |
| Tr 28 × 3 | 28 | 3 | 26.500 | 28.500 | 24.500 | 25.000 | 0.25 |
| Tr 28 × 5 | 28 | 5 | 25.500 | 28.500 | 22.500 | 23.000 | 0.25 |
| Tr 30 × 3 | 30 | 3 | 28.500 | 30.500 | 26.500 | 27.000 | 0.25 |
| Tr 30 × 6 | 30 | 6 | 27.000 | 30.500 | 23.500 | 24.000 | 0.25 |
| Tr 32 × 3 | 32 | 3 | 30.500 | 32.500 | 28.500 | 29.000 | 0.25 |
| Tr 32 × 6 | 32 | 6 | 29.000 | 32.500 | 25.500 | 26.000 | 0.25 |
| Tr 34 × 3 | 34 | 3 | 32.500 | 34.500 | 30.500 | 31.000 | 0.25 |
| Tr 34 × 6 | 34 | 6 | 31.000 | 34.500 | 27.500 | 28.000 | 0.25 |
| Tr 36 × 3 | 36 | 3 | 34.500 | 36.500 | 32.500 | 33.000 | 0.25 |
| Tr 36 × 6 | 36 | 6 | 33.000 | 36.500 | 29.500 | 30.000 | 0.25 |
| Tr 38 × 3 | 38 | 3 | 36.500 | 38.500 | 34.500 | 35.000 | 0.25 |
| Tr 38 × 7 | 38 | 7 | 34.500 | 39.000 | 30.000 | 31.000 | 0.5 |
| Tr 40 × 3 | 40 | 3 | 38.500 | 40.500 | 36.500 | 37.000 | 0.25 |
| Tr 40 × 7 | 40 | 7 | 36.500 | 41.000 | 32.000 | 33.000 | 0.5 |
| Tr 42 × 3 | 42 | 3 | 40.500 | 42.500 | 38.500 | 39.000 | 0.25 |
| Tr 42 × 7 | 42 | 7 | 38.500 | 43.000 | 34.000 | 35.000 | 0.5 |
| Tr 44 × 3 | 44 | 3 | 42.500 | 44.500 | 40.500 | 41.000 | 0.25 |
| Tr 44 × 7 | 44 | 7 | 40.500 | 45.000 | 36.000 | 37.000 | 0.5 |
| Tr 46 × 3 | 46 | 3 | 44.500 | 46.500 | 42.500 | 43.000 | 0.25 |
| Tr 46 × 8 | 46 | 8 | 42.000 | 47.000 | 37.000 | 38.000 | 0.5 |
| Tr 48 × 3 | 48 | 3 | 46.500 | 48.500 | 44.500 | 45.000 | 0.25 |
| Tr 48 × 8 | 48 | 8 | 44.000 | 49.000 | 39.000 | 40.000 | 0.5 |
| Tr 50 × 3 | 50 | 3 | 48.500 | 50.500 | 46.500 | 47.000 | 0.25 |
| Tr 50 × 8 | 50 | 8 | 46.000 | 51.000 | 41.000 | 42.000 | 0.5 |
| Tr 52 × 3 | 52 | 3 | 50.500 | 52.500 | 48.500 | 49.000 | 0.25 |
| Tr 52 × 8 | 52 | 8 | 48.000 | 53.000 | 43.000 | 44.000 | 0.5 |
| Tr 55 × 4 | 55 | 4 | 53.000 | 55.500 | 50.500 | 51.000 | 0.25 |
| Tr 55 × 9 | 55 | 9 | 50.500 | 56.000 | 45.000 | 46.000 | 0.5 |
| Tr 60 × 3 | 60 | 3 | 58.500 | 60.500 | 56.500 | 57.000 | 0.25 |
| Tr 60 × 9 | 60 | 9 | 55.500 | 61.000 | 50.000 | 51.000 | 0.5 |
| Tr 65 × 4 | 65 | 4 | 63.000 | 65.500 | 60.500 | 61.000 | 0.25 |
| Tr 65 × 10 | 65 | 10 | 60.000 | 66.000 | 54.000 | 55.000 | 0.5 |
| Tr 70 × 4 | 70 | 4 | 68.000 | 70.500 | 65.500 | 66.000 | 0.25 |
| Tr 70 × 10 | 70 | 10 | 65.000 | 71.000 | 59.000 | 60.000 | 0.5 |
| Tr 75 × 4 | 75 | 4 | 73.000 | 75.500 | 70.500 | 71.000 | 0.25 |
| Tr 75 × 10 | 75 | 10 | 70.000 | 76.000 | 64.000 | 65.000 | 0.5 |
| Tr 80 × 4 | 80 | 4 | 78.000 | 80.500 | 75.500 | 76.000 | 0.25 |
| Tr 80 × 10 | 80 | 10 | 75.000 | 81.000 | 69.000 | 70.000 | 0.5 |
| Tr 85 × 4 | 85 | 4 | 83.000 | 85.500 | 80.500 | 81.000 | 0.25 |
| Tr 85 × 12 | 85 | 12 | 79.000 | 86.000 | 72.000 | 73.000 | 0.5 |
| Tr 90 × 4 | 90 | 4 | 88.000 | 90.500 | 85.500 | 86.000 | 0.25 |
| Tr 90 × 12 | 90 | 12 | 84.000 | 91.000 | 77.000 | 78.000 | 0.5 |
| Tr 95 × 4 | 95 | 4 | 93.000 | 95.500 | 90.500 | 91.000 | 0.25 |
| Tr 95 × 12 | 95 | 12 | 89.000 | 96.000 | 82.000 | 83.000 | 0.5 |
| Tr 100 × 4 | 100 | 4 | 98.000 | 100.500 | 95.500 | 96.000 | 0.25 |
| Tr 100 × 12 | 100 | 12 | 94.000 | 101.000 | 87.000 | 88.000 | 0.5 |
| D s | P | E | h e | a | b | K s | h s | D n | K n | h n |
|---|---|---|---|---|---|---|---|---|---|---|
| Dimensions in mm | ||||||||||
| 10 | 3 | 8.5 | 1.25 | 0.25 | 0.5 | 6.5 | 1.75 | 10.5 | 7.5 | 1.5 |
| 12 | 3 | 10.5 | 1.25 | 0.25 | 0.5 | 8.5 | 1.75 | 12.5 | 9.5 | 1.5 |
| 14 | 4 | 12 | 1.75 | 0.25 | 0.5 | 9.5 | 2.25 | 14.5 | 10.5 | 2 |
| 16 | 4 | 14 | 1.75 | 0.25 | 0.5 | 11.5 | 2.25 | 16.5 | 12.5 | 2 |
| 18 | 4 | 16 | 1.75 | 0.25 | 0.5 | 13.5 | 2.25 | 18.5 | 14.5 | 2 |
| 20 | 4 | 18 | 1.75 | 0.25 | 0.5 | 15.5 | 2.25 | 20.5 | 16.5 | 2 |
| 22 | 5 | 19.5 | 2 | 0.25 | 0.75 | 16.5 | 2.25 | 22.5 | 18 | 2 |
| 24 | 5 | 21.5 | 2 | 0.25 | 0.75 | 18.5 | 2.25 | 24.5 | 20 | 2.25 |
| 26 | 5 | 23.5 | 2 | 0.25 | 0.75 | 20.5 | 2.25 | 26.5 | 22 | 2.25 |
| 28 | 5 | 25.5 | 2 | 0.25 | 0.75 | 22.5 | 2.25 | 28.5 | 24 | 2.25 |
| 30 | 6 | 27 | 2.5 | 0.25 | 0.75 | 23.5 | 3.25 | 30.5 | 25 | 2.75 |
| 32 | 6 | 29 | 2.5 | 0.25 | 0.75 | 25.5 | 3.25 | 32.5 | 27 | 2.75 |
| 36 | 6 | 33 | 2.5 | 0.25 | 0.75 | 29.5 | 3.25 | 36.5 | 31 | 2.75 |
| 40 | 7 | 36.5 | 3 | 0.25 | 0.75 | 32.5 | 3.75 | 40.5 | 34 | 3.25 |
| 44 | 7 | 40.5 | 3 | 0.25 | 0.75 | 36.5 | 3.75 | 44.5 | 38 | 3.25 |
| 48 | 8 | 44 | 3.5 | 0.25 | 0.75 | 39.5 | 4.25 | 48.5 | 41 | 3.75 |
| 50 | 8 | 46 | 3.5 | 0.25 | 0.75 | 41.5 | 4.25 | 50.5 | 43 | 3.75 |
| 52 | 8 | 48 | 3.5 | 0.25 | 0.75 | 43.5 | 4.25 | 52.5 | 45 | 3.75 |
| 55 | 9 | 50.5 | 4 | 0.25 | 0.75 | 45.5 | 4.75 | 55.5 | 47 | 4.25 |
| 60 | 9 | 55.5 | 4 | 0.25 | 0.75 | 50.5 | 4.75 | 60.5 | 52 | 4.25 |
| 65 | 10 | 60 | 4.5 | 0.25 | 0.75 | 54.5 | 5.25 | 65.5 | 56 | 4.75 |
| 70 | 10 | 65 | 4.5 | 0.25 | 0.75 | 59.5 | 5.25 | 70.5 | 61 | 4.75 |
| 75 | 10 | 70 | 4.5 | 0.25 | 0.75 | 64.5 | 5.25 | 75.5 | 66 | 4.75 |
| 80 | 10 | 75 | 4.5 | 0.25 | 0.75 | 69.5 | 5.25 | 80.5 | 71 | 4.75 |
| 85 | 12 | 79 | 5.5 | 0.25 | 0.75 | 72.5 | 6.25 | 85.5 | 74 | 5.75 |
| 90 | 12 | 84 | 5.5 | 0.25 | 0.75 | 77.5 | 6.25 | 90.5 | 79 | 5.75 |
| 95 | 12 | 89 | 5.5 | 0.25 | 0.75 | 82.5 | 6.25 | 95.5 | 84 | 5.75 |
| 100 | 12 | 94 | 5.5 | 0.25 | 0.75 | 87.5 | 6.25 | 100.5 | 89 | 5.75 |
- Row 1 (Dimensions in mm): the source's own unit-banner row - 'Dimensions in mm' spanning the grid - is carried as printed with its blank cells
Materials
- Material and tolerance class specified per RFQ — lead screws commonly run medium-carbon or alloy steel with the flank profile thread-milled or rolled, against bronze or polymer nuts for wear; stainless for corrosive or food-washdown duty. State the axial load, travel per revolution and duty cycle at quotation, since pitch choice (the collected ladder offers two pitches on most diameters) is a wear-and-speed decision, not a stocking one
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 (ISO 2904 Metric Trapezoidal Screw Threads) 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 1,000–10,000 pieces depending on size. Stock items run 3–7 days. High-strength and custom parts run 15–25 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
ISO 2904 trapezoidal threads or the DIN 103 trapezoidal line on this site — which designation do I order?
Order by the standard your drawing names — they are different designations, not duplicates. The DIN 103 pages here tabulate the rod and its mating hex and round nuts from Tr 10 to Tr 60 with a pitch-per-size table; this ISO 2904 page carries the full ISO designation ladder, Tr 8 × 1.5 to Tr 100 × 12, with the complete basic geometry per designation (pitch diameter d 2 = D 2, minors d 3 and D 1, internal major D 4, crest clearance a c). The ISO ladder extends both finer (Tr 8, Tr 9) and much coarser (Tr 85 × 12, Tr 90 × 12, Tr 95 × 12, Tr 100 × 12) than the collected DIN 103 pitch table. If the drawing just says "Tr thread", match the diameter and pitch from the table — e.g. Tr 40 × 7 — and confirm the tolerance class per RFQ: the ISO tolerance system is ISO 2903, and the class is chosen on the fit the application needs (tight for position-holding screws, freer for fast-traversing drives).
What do the symbols d 2, D 4, d 3, D 1 and a c mean when reading the dimension table?
They are the ISO trapezoidal design-profile diameters, carried verbatim from the collected page. d 2 = D 2 is the pitch diameter — identical for screw and nut, and the reference for thread-fit measurement. d 3 is the external (screw) minor diameter of the design profile; D 1 is the internal (nut) minor diameter; D 4 is the internal major diameter, set larger than d so the crests never bind. a c is the crest clearance that creates that gap — 0.15 mm at the 1.5 mm pitches, 0.25 mm through P 6, and 0.5 mm from P 7 up. Worked example from the table: Tr 40 × 7 has d 40, d 2 = D 2 = 36.5, D 4 = 41.0, d 3 = 32.0, D 1 = 33.0, a c 0.5 — the screw's working depth sits between d 3 and d 2, and the nut's between D 1 and D 2, with the clearance keeping the flanks, not the crests, in contact. These are basic-profile values: actual manufacture applies a tolerance class per ISO 2903, which is quoted per RFQ.
Related knowledge
- What Bolt Property Classes 8.8, 10.9 and 12.9 Encode — and When High Strength Stops Being the Right Choice
- Bolt Grade Selection: ISO 898-1 8.8/10.9/12.9 vs ASTM A307 and A325
- 8.8 vs 10.9 vs 12.9 Bolts: Strength, Hardness and Cost — What the Evidence Settles
- Calculating Bolt Preload and Clamp Force: Torque, Friction and Tightening Method
- How to Determine Tightening Torque and Choose a Tightening Method for a Bolted Joint
- Fastener Failure Modes: Which Fatigue, Creep and SCC Controls the Evidence Supports
- Hydrogen Embrittlement in High-Strength Bolts: Which Grades Need Controls, Which Coatings and Baking Schedules Are Acceptable, and What to Require Before the RFQ
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