Torx / hexalobular drive sizes T1–T100 (ISO 10664): A and B across lobes, gauge limits for A, B, Ri, Re and depth H, and the screw size each fits — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/torx-hexalobular-drive-sizes-iso-10664/ (sheet CC BY 4.0) Basis: ISO 10664:2014 sample pages (Table 1 nominal A and B; Table 3 limiting sizes of the GO gauge), the screw-to-socket pairing from the ISO 14579 / 14580 / 14583 tables on fasten.it, Westfield Fasteners and Aspen Fasteners; numbers only Catalog version: 2026-10-20 Sizes: see table below - ISO 10664 specifies the hexalobular internal driving feature (the 'Torx' socket in a screw head and the matching bit). The standard numbers sockets 1 to 100; the trade names T10, T15, T20 and so on use the same numbers, and bit sellers list tamper-resistant bits as T7 to T55 (McMaster-Carr). In ISO 14579 / 14580 / 14583 the screw tables print the number in a 'Socket Nr' column; this page uses 'T' only in search terms. - A is the nominal across the outer lobes and B the nominal across the inner (between-lobe) diameter, both mm, from Table 1 of the 2014 sample pages. For socket 45 the sample prints A = 7.93 while the screw standards (fasten.it, Westfield, Aspen) print A = 7.95 for the same socket; both are shown here (7.93 in the table, 7.95 in the screw-size column of the next page). For the other sockets in the screw tables (6, 8, 10, 15, 20, 25, 30, 50, 55, 60, 70, 80, 90) A matches Table 1. - Limits are Table 3 of the sample pages, the GO gauge that must enter the socket: A, B, Ri (inner radius) and Re (outer radius) as min / max, and H, the gauge height, min / max, all mm. The sample does not define Ri, Re and H in words (they are on Figures 3 and 4, not in the text), so only the printed names are used. Table 4 (the NO-GO gauge for A and Re) stops at socket 80 in the text read and its column alignment was not clear, so it is left out; no nominal Ri or Re is printed in the pages read. - Screw pairing (last column) is read from the ISO 14579 / 14580 / 14583 tables: M2 6, M2.5 8, M3 10, M3.5 15, M4 20, M5 25, M6 30, M8 45, M10 50, and for ISO 14579 only M12 55, M14 60, M16 70, M18 80, M20 90. Other standards and makers (self-tapping, wood and deck screws) pair sizes differently: a Simpson Deck-Drive #10 deck screw uses T25 and a #8 uses T20 (see deck-screws-8-10-simpson-grk). - Security (pin-in, tamper-resistant) Torx: the bit has a hole for the pin in the middle of the screw's socket. McMaster-Carr lists these bits as T7, T8, T9, T10, T15, T20, T25, T27, T30, T35, T40, T45, T50 and T55; the pin diameter and the bit's centre hole are not published as numbers in any source read, so none is shown. Torx Plus and other hexalobular variants are different profiles and are not on this page. - No file: the contour is defined by A, B, Ri, Re and the gauge figures, which are not available as text, so a profile drawn from these numbers alone would be a guess. Hexalobular head screws with true head sizes: hexalobular-socket-screws-iso-14579-14580-14583. socket no. (T size) A nominal B nominal GO gauge A min – max GO gauge B min – max Ri min – max Re min – max H min – max screw size (ISO 14579 / 14580 / 14583) 1 0.9 0.6 0.841 – 0.855 0.592 – 0.607 0.198 – 0.204 0.055 – 0.062 0.64 – 1.14 — 2 1 0.7 0.953 – 0.967 0.674 – 0.688 0.221 – 0.227 0.065 – 0.072 1.15 – 1.65 — 3 1.2 0.85 1.131 – 1.145 0.8 – 0.815 0.263 – 0.27 0.078 – 0.085 1.15 – 1.65 — 4 1.35 1 1.291 – 1.305 0.912 – 0.927 0.305 – 0.312 0.087 – 0.093 1.15 – 1.65 — 5 1.5 1.1 1.415 – 1.43 1.013 – 1.028 0.318 – 0.342 0.107 – 0.111 1.15 – 1.65 — 6 1.75 1.27 1.695 – 1.709 1.21 – 1.224 0.371 – 0.396 0.13 – 0.134 1.33 – 1.82 M2 7 2.1 1.5 2.012 – 2.026 1.437 – 1.453 0.442 – 0.45 0.157 – 0.165 2.54 – 3.05 — 8 2.4 1.75 2.335 – 2.349 1.672 – 1.686 0.498 – 0.523 0.188 – 0.193 2.54 – 3.05 M2.5 9 2.6 1.9 2.52 – 2.534 1.809 – 1.823 0.542 – 0.566 0.204 – 0.21 2.79 – 3.3 — 10 2.8 2.05 2.761 – 2.776 1.979 – 1.993 0.585 – 0.609 0.227 – 0.231 3.05 – 3.56 M3 15 3.35 2.4 3.295 – 3.309 2.353 – 2.367 0.704 – 0.728 0.265 – 0.269 3.3 – 3.81 M3.5 (ISO 14580 / 14583) 20 3.95 2.85 3.879 – 3.893 2.764 – 2.778 0.846 – 0.871 0.303 – 0.307 3.56 – 4.07 M4 25 4.5 3.25 4.451 – 4.465 3.17 – 3.185 0.907 – 0.932 0.371 – 0.378 3.94 – 4.45 M5 27 5.1 3.68 5.009 – 5.024 3.564 – 3.578 1.095 – 1.12 0.387 – 0.393 4.19 – 4.7 — 30 5.6 4.05 5.543 – 5.557 3.958 – 3.972 1.182 – 1.206 0.448 – 0.454 4.44 – 4.95 M6 40 6.75 4.85 6.673 – 6.687 4.766 – 4.78 1.415 – 1.44 0.544 – 0.548 5.08 – 5.59 — 45 7.93 5.64 7.841 – 7.856 5.555 – 5.57 1.784 – 1.808 0.572 – 0.576 5.71 – 6.22 M8 50 8.95 6.45 8.857 – 8.872 6.366 – 6.38 1.804 – 1.828 0.773 – 0.777 5.97 – 6.48 M10 55 11.35 8.05 11.245 – 11.259 7.93 – 7.945 2.657 – 2.682 0.765 – 0.769 6.22 – 6.73 M12 (ISO 14579) 60 13.45 9.6 13.302 – 13.317 9.49 – 9.504 2.871 – 2.895 1.065 – 1.069 7.68 – 8.17 M14 (ISO 14579) 70 15.7 11.2 15.588 – 15.603 11.085 – 11.099 3.465 – 3.489 1.192 – 1.196 8.46 – 8.96 M16 (ISO 14579) 80 17.75 12.8 17.619 – 17.635 12.646 – 12.661 3.625 – 3.629 1.524 – 1.529 9.4 – 9.9 M18 (ISO 14579) 90 20.2 14.4 20.021 – 20.035 14.232 – 14.246 4.456 – 4.48 1.527 – 1.534 10.06 – 10.56 M20 (ISO 14579) 100 22.4 16 22.231 – 22.245 15.82 – 15.834 4.913 – 4.937 1.718 – 1.724 10.85 – 11.35 — Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - iTeh Standards: ISO 10664:2014 sample pages: Table 1 nominal A and B, Table 3 limiting sizes of the GO gauge (A, B, Ri, Re, H) for socket nos. 1 to 100 — web — Standards-body sample pages; numbers only — https://cdn.standards.iteh.ai/samples/63207/f79670cf0a214881aa40b4822580cce3/ISO-10664-2014.pdf - McMaster-Carr: Tamper-resistant (pin-in) Torx bits, T7 to T55 (free STEP/IGES per part, for your own design use; no redistribution) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution [verify license at link] — https://www.mcmaster.com/torx-security-bits No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned. API: https://xemstudio.com/api/geometry?object=torx-hexalobular-drive-sizes-iso-10664