Precision measurement technology in ZIKO Technik's calibration laboratory

Thread Chart

Pitch, thread angle and diameter for Metric ISO, UN, pipe threads and trapezoidal threads – for quick reference.

Whether it's a spare part for an older British machine, a US-made supplied part, or a fastening to DIN — our thread chart compares the most common thread standards directly in millimeters. All values are calculated from the standardized thread profiles or taken from the corresponding standard tables (see sources below) and are meant for quick orientation. For special sizes such as fine threads with a custom pitch or trapezoidal threads to your own specification, use the thread calculator right below.

Disclaimer: The values in the thread chart and the thread calculator have been carefully calculated or taken from the standards, but without guarantee. They are for orientation only and replace neither the applicable standard nor a bolt calculation (e.g. to VDI 2230). Use is at your own risk; liability is excluded unless it is based on intent or gross negligence or concerns injury to life, body or health.

Thread Calculator for Custom Dimensions

Same 60° geometry as metric ISO thread, pitch P = 1/TPI (inch). Reference-checked against 1/4"-20 UNC.

Search All Standard Sizes

127 thread sizes in the database

Scroll the table sideways to see all columns.

Designation Standard Pitch / TPI Thread Angle Major Ø (mm) Pitch Ø (mm) Minor Ø (bolt) (mm) Note
M1.6 ISO 724 / DIN 13-1 0.35 mm 60° 1.6 1.373 1.171 –
M1.6 x 0.2 (Fine) ISO 724 / DIN 13-1 0.2 mm 60° 1.6 1.47 1.355 –
M2 ISO 724 / DIN 13-1 0.4 mm 60° 2 1.74 1.509 –
M2 x 0.25 (Fine) ISO 724 / DIN 13-1 0.25 mm 60° 2 1.838 1.693 –
M2.5 ISO 724 / DIN 13-1 0.45 mm 60° 2.5 2.208 1.948 –
M2.5 x 0.35 (Fine) ISO 724 / DIN 13-1 0.35 mm 60° 2.5 2.273 2.071 –
M3 ISO 724 / DIN 13-1 0.5 mm 60° 3 2.675 2.387 –
M3 x 0.35 (Fine) ISO 724 / DIN 13-1 0.35 mm 60° 3 2.773 2.571 –
M4 ISO 724 / DIN 13-1 0.7 mm 60° 4 3.545 3.141 –
M4 x 0.5 (Fine) ISO 724 / DIN 13-1 0.5 mm 60° 4 3.675 3.387 –
M5 ISO 724 / DIN 13-1 0.8 mm 60° 5 4.48 4.019 –
M5 x 0.5 (Fine) ISO 724 / DIN 13-1 0.5 mm 60° 5 4.675 4.387 –
M6 ISO 724 / DIN 13-1 1 mm 60° 6 5.35 4.773 –
M6 x 0.75 (Fine) ISO 724 / DIN 13-1 0.75 mm 60° 6 5.513 5.08 –
M8 ISO 724 / DIN 13-1 1.25 mm 60° 8 7.188 6.466 –
M8 x 1 (Fine) ISO 724 / DIN 13-1 1 mm 60° 8 7.35 6.773 –
M10 ISO 724 / DIN 13-1 1.5 mm 60° 10 9.026 8.16 –
M10 x 1.25 (Fine) ISO 724 / DIN 13-1 1.25 mm 60° 10 9.188 8.466 –
M12 ISO 724 / DIN 13-1 1.75 mm 60° 12 10.863 9.853 –
M12 x 1.5 (Fine) ISO 724 / DIN 13-1 1.5 mm 60° 12 11.026 10.16 –
M14 ISO 724 / DIN 13-1 2 mm 60° 14 12.701 11.546 –
M14 x 1.5 (Fine) ISO 724 / DIN 13-1 1.5 mm 60° 14 13.026 12.16 –
M16 ISO 724 / DIN 13-1 2 mm 60° 16 14.701 13.546 –
M16 x 1.5 (Fine) ISO 724 / DIN 13-1 1.5 mm 60° 16 15.026 14.16 –
M18 ISO 724 / DIN 13-1 2.5 mm 60° 18 16.376 14.933 –
M18 x 2 (Fine) ISO 724 / DIN 13-1 2 mm 60° 18 16.701 15.546 –
M20 ISO 724 / DIN 13-1 2.5 mm 60° 20 18.376 16.933 –
M20 x 2 (Fine) ISO 724 / DIN 13-1 2 mm 60° 20 18.701 17.546 –
M22 ISO 724 / DIN 13-1 2.5 mm 60° 22 20.376 18.933 –
M22 x 2 (Fine) ISO 724 / DIN 13-1 2 mm 60° 22 20.701 19.546 –
M24 ISO 724 / DIN 13-1 3 mm 60° 24 22.051 20.319 –
M24 x 2 (Fine) ISO 724 / DIN 13-1 2 mm 60° 24 22.701 21.546 –
M27 ISO 724 / DIN 13-1 3 mm 60° 27 25.051 23.319 –
M27 x 2 (Fine) ISO 724 / DIN 13-1 2 mm 60° 27 25.701 24.546 –
M30 ISO 724 / DIN 13-1 3.5 mm 60° 30 27.727 25.706 –
M30 x 2 (Fine) ISO 724 / DIN 13-1 2 mm 60° 30 28.701 27.546 –
M33 ISO 724 / DIN 13-1 3.5 mm 60° 33 30.727 28.706 –
M33 x 2 (Fine) ISO 724 / DIN 13-1 2 mm 60° 33 31.701 30.546 –
M36 ISO 724 / DIN 13-1 4 mm 60° 36 33.402 31.093 –
M36 x 3 (Fine) ISO 724 / DIN 13-1 3 mm 60° 36 34.051 32.319 –
M39 ISO 724 / DIN 13-1 4 mm 60° 39 36.402 34.093 –
M39 x 3 (Fine) ISO 724 / DIN 13-1 3 mm 60° 39 37.051 35.319 –
M42 ISO 724 / DIN 13-1 4.5 mm 60° 42 39.077 36.479 –
M42 x 3 (Fine) ISO 724 / DIN 13-1 3 mm 60° 42 40.051 38.319 –
M45 ISO 724 / DIN 13-1 4.5 mm 60° 45 42.077 39.479 –
M45 x 3 (Fine) ISO 724 / DIN 13-1 3 mm 60° 45 43.051 41.319 –
M48 ISO 724 / DIN 13-1 5 mm 60° 48 44.752 41.866 –
M48 x 3 (Fine) ISO 724 / DIN 13-1 3 mm 60° 48 46.051 44.319 –
M52 ISO 724 / DIN 13-1 5 mm 60° 52 48.752 45.866 –
M52 x 4 (Fine) ISO 724 / DIN 13-1 4 mm 60° 52 49.402 47.093 –
M56 ISO 724 / DIN 13-1 5.5 mm 60° 56 52.428 49.252 –
M56 x 4 (Fine) ISO 724 / DIN 13-1 4 mm 60° 56 53.402 51.093 –
M60 ISO 724 / DIN 13-1 5.5 mm 60° 60 56.428 53.252 –
M60 x 4 (Fine) ISO 724 / DIN 13-1 4 mm 60° 60 57.402 55.093 –
M64 ISO 724 / DIN 13-1 6 mm 60° 64 60.103 56.639 –
M64 x 4 (Fine) ISO 724 / DIN 13-1 4 mm 60° 64 61.402 59.093 –
#4-40 UNC ASME B1.1 (UN) 40 TPI (0.635 mm) 60° 2.845 2.432 2.066 –
#4-48 UNF ASME B1.1 (UN) 48 TPI (0.529 mm) 60° 2.845 2.501 2.196 –
#6-32 UNC ASME B1.1 (UN) 32 TPI (0.794 mm) 60° 3.505 2.99 2.531 –
#6-40 UNF ASME B1.1 (UN) 40 TPI (0.635 mm) 60° 3.505 3.093 2.726 –
#8-32 UNC ASME B1.1 (UN) 32 TPI (0.794 mm) 60° 4.166 3.65 3.192 –
#8-36 UNF ASME B1.1 (UN) 36 TPI (0.706 mm) 60° 4.166 3.707 3.3 –
#10-24 UNC ASME B1.1 (UN) 24 TPI (1.058 mm) 60° 4.826 4.139 3.528 –
#10-32 UNF ASME B1.1 (UN) 32 TPI (0.794 mm) 60° 4.826 4.31 3.852 –
#12-24 UNC ASME B1.1 (UN) 24 TPI (1.058 mm) 60° 5.486 4.799 4.188 –
#12-28 UNF ASME B1.1 (UN) 28 TPI (0.907 mm) 60° 5.486 4.897 4.373 –
1/4"-20 UNC ASME B1.1 (UN) 20 TPI (1.27 mm) 60° 6.35 5.525 4.792 –
1/4"-28 UNF ASME B1.1 (UN) 28 TPI (0.907 mm) 60° 6.35 5.761 5.237 –
5/16"-18 UNC ASME B1.1 (UN) 18 TPI (1.411 mm) 60° 7.938 7.021 6.206 –
5/16"-24 UNF ASME B1.1 (UN) 24 TPI (1.058 mm) 60° 7.938 7.25 6.639 –
3/8"-16 UNC ASME B1.1 (UN) 16 TPI (1.587 mm) 60° 9.525 8.494 7.577 –
3/8"-24 UNF ASME B1.1 (UN) 24 TPI (1.058 mm) 60° 9.525 8.838 8.227 –
7/16"-14 UNC ASME B1.1 (UN) 14 TPI (1.814 mm) 60° 11.112 9.934 8.887 –
7/16"-20 UNF ASME B1.1 (UN) 20 TPI (1.27 mm) 60° 11.112 10.288 9.554 –
1/2"-13 UNC ASME B1.1 (UN) 13 TPI (1.954 mm) 60° 12.7 11.431 10.303 –
1/2"-20 UNF ASME B1.1 (UN) 20 TPI (1.27 mm) 60° 12.7 11.875 11.142 –
9/16"-12 UNC ASME B1.1 (UN) 12 TPI (2.117 mm) 60° 14.287 12.913 11.691 –
9/16"-18 UNF ASME B1.1 (UN) 18 TPI (1.411 mm) 60° 14.287 13.371 12.556 –
5/8"-11 UNC ASME B1.1 (UN) 11 TPI (2.309 mm) 60° 15.875 14.375 13.042 –
5/8"-18 UNF ASME B1.1 (UN) 18 TPI (1.411 mm) 60° 15.875 14.958 14.144 –
3/4"-10 UNC ASME B1.1 (UN) 10 TPI (2.54 mm) 60° 19.05 17.4 15.934 –
3/4"-16 UNF ASME B1.1 (UN) 16 TPI (1.587 mm) 60° 19.05 18.019 17.102 –
7/8"-9 UNC ASME B1.1 (UN) 9 TPI (2.822 mm) 60° 22.225 20.392 18.763 –
7/8"-14 UNF ASME B1.1 (UN) 14 TPI (1.814 mm) 60° 22.225 21.047 19.999 –
1"-8 UNC ASME B1.1 (UN) 8 TPI (3.175 mm) 60° 25.4 23.338 21.505 –
1"-12 UNF ASME B1.1 (UN) 12 TPI (2.117 mm) 60° 25.4 24.025 22.803 –
G 1/8 DIN ISO 228 (BSPP, cylindrical) 28 TPI (0.907 mm) 55° 9.73 9.15 8.57 Cylindrical pipe thread, seals via a separate sealing element (e.g. O-ring).
R 1/8 DIN 2999 / ISO 7 (BSPT, tapered) 28 TPI (0.907 mm) 55° 9.73 9.15 8.57 Tapered pipe thread (1:16 taper), seals in the thread itself. Dimensions at the gauge plane same as G.
G 1/4 DIN ISO 228 (BSPP, cylindrical) 19 TPI (1.337 mm) 55° 13.16 12.3 11.45 Cylindrical pipe thread, seals via a separate sealing element (e.g. O-ring).
R 1/4 DIN 2999 / ISO 7 (BSPT, tapered) 19 TPI (1.337 mm) 55° 13.16 12.3 11.45 Tapered pipe thread (1:16 taper), seals in the thread itself. Dimensions at the gauge plane same as G.
G 3/8 DIN ISO 228 (BSPP, cylindrical) 19 TPI (1.337 mm) 55° 16.66 15.81 14.95 Cylindrical pipe thread, seals via a separate sealing element (e.g. O-ring).
R 3/8 DIN 2999 / ISO 7 (BSPT, tapered) 19 TPI (1.337 mm) 55° 16.66 15.81 14.95 Tapered pipe thread (1:16 taper), seals in the thread itself. Dimensions at the gauge plane same as G.
G 1/2 DIN ISO 228 (BSPP, cylindrical) 14 TPI (1.814 mm) 55° 20.96 19.79 18.63 Cylindrical pipe thread, seals via a separate sealing element (e.g. O-ring).
R 1/2 DIN 2999 / ISO 7 (BSPT, tapered) 14 TPI (1.814 mm) 55° 20.96 19.79 18.63 Tapered pipe thread (1:16 taper), seals in the thread itself. Dimensions at the gauge plane same as G.
G 3/4 DIN ISO 228 (BSPP, cylindrical) 14 TPI (1.814 mm) 55° 26.44 25.28 24.12 Cylindrical pipe thread, seals via a separate sealing element (e.g. O-ring).
R 3/4 DIN 2999 / ISO 7 (BSPT, tapered) 14 TPI (1.814 mm) 55° 26.44 25.28 24.12 Tapered pipe thread (1:16 taper), seals in the thread itself. Dimensions at the gauge plane same as G.
G 1 DIN ISO 228 (BSPP, cylindrical) 11 TPI (2.309 mm) 55° 33.25 31.77 30.29 Cylindrical pipe thread, seals via a separate sealing element (e.g. O-ring).
R 1 DIN 2999 / ISO 7 (BSPT, tapered) 11 TPI (2.309 mm) 55° 33.25 31.77 30.29 Tapered pipe thread (1:16 taper), seals in the thread itself. Dimensions at the gauge plane same as G.
G 1 1/4 DIN ISO 228 (BSPP, cylindrical) 11 TPI (2.309 mm) 55° 41.91 40.43 38.95 Cylindrical pipe thread, seals via a separate sealing element (e.g. O-ring).
R 1 1/4 DIN 2999 / ISO 7 (BSPT, tapered) 11 TPI (2.309 mm) 55° 41.91 40.43 38.95 Tapered pipe thread (1:16 taper), seals in the thread itself. Dimensions at the gauge plane same as G.
G 1 1/2 DIN ISO 228 (BSPP, cylindrical) 11 TPI (2.309 mm) 55° 47.8 46.32 44.85 Cylindrical pipe thread, seals via a separate sealing element (e.g. O-ring).
R 1 1/2 DIN 2999 / ISO 7 (BSPT, tapered) 11 TPI (2.309 mm) 55° 47.8 46.32 44.85 Tapered pipe thread (1:16 taper), seals in the thread itself. Dimensions at the gauge plane same as G.
G 2 DIN ISO 228 (BSPP, cylindrical) 11 TPI (2.309 mm) 55° 59.61 58.14 56.66 Cylindrical pipe thread, seals via a separate sealing element (e.g. O-ring).
R 2 DIN 2999 / ISO 7 (BSPT, tapered) 11 TPI (2.309 mm) 55° 59.61 58.14 56.66 Tapered pipe thread (1:16 taper), seals in the thread itself. Dimensions at the gauge plane same as G.
Tr 8x1.5 DIN 103 1.5 mm 30° 8 7.25 6.2 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 10x2 DIN 103 2 mm 30° 10 9 7.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 12x3 DIN 103 3 mm 30° 12 10.5 8.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 14x3 DIN 103 3 mm 30° 14 12.5 10.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 16x4 DIN 103 4 mm 30° 16 14 11.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 18x4 DIN 103 4 mm 30° 18 16 13.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 20x4 DIN 103 4 mm 30° 20 18 15.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 22x5 DIN 103 5 mm 30° 22 19.5 16.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 24x5 DIN 103 5 mm 30° 24 21.5 18.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 26x5 DIN 103 5 mm 30° 26 23.5 20.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 28x5 DIN 103 5 mm 30° 28 25.5 22.5 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 30x6 DIN 103 6 mm 30° 30 27 23 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 32x6 DIN 103 6 mm 30° 32 29 25 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 36x6 DIN 103 6 mm 30° 36 33 29 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 40x7 DIN 103 7 mm 30° 40 36.5 32 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 44x7 DIN 103 7 mm 30° 44 40.5 36 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 48x8 DIN 103 8 mm 30° 48 44 39 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 52x8 DIN 103 8 mm 30° 52 48 43 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 60x9 DIN 103 9 mm 30° 60 55.5 50 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 70x10 DIN 103 10 mm 30° 70 65 59 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 80x10 DIN 103 10 mm 30° 80 75 69 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 90x12 DIN 103 12 mm 30° 90 84 77 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.
Tr 100x12 DIN 103 12 mm 30° 100 94 87 Single-start trapezoidal thread (n=1); D1/D4 (nut) - see thread calculator.

What Do the Terms Mean?

  • Thread angle (flank angle α) – the angle between the two flanks of the thread profile, measured in the axial section. Metric ISO and UN: 60°, Whitworth and pipe threads: 55°, trapezoidal threads per DIN 103: 30°.
  • Pitch (P) – the distance between two adjacent thread crests, measured parallel to the thread axis. On multi-start threads, the advance per revolution (lead Ph) is n times the pitch: Ph = n · P. Every thread in this table is single-start, so Ph = P.
  • Major diameter – the largest diameter of the thread, measured across the thread crests (for bolts/external threads).
  • Pitch diameter (also effective or mean diameter) – the diameter at the level of theoretical flank contact, decisive for fit.
  • Simple pitch diameter – the pitch diameter as measured directly at a single position, without accounting for pitch and flank angle deviations. See the explanation below.
  • Minor diameter – the smallest diameter, measured across the thread root; among other things, it determines the remaining cross-sectional area of the bolt. Throughout the table below, this consistently means the minor diameter of the external thread (bolt) – the differing value for internal threads (nut) is shown in its own column for Metric ISO, and can be looked up for every thread type in the thread calculator above.

Where Do These Values Come From?

Metric-ISO and UN threads are calculated from pitch according to the standardized profile formulas (ISO 724 and ASME B1.1, 60° thread angle). Pipe thread values (G, R) are taken directly from the standard tables per DIN ISO 228 / DIN 2999, likewise calculated on the basis of the Whitworth profile formula (55° thread angle). Trapezoidal thread values are calculated per DIN 103 (30° thread angle). For custom diameters, fine threads or special sizes outside these standard series, use the thread calculator above.

Despite careful review, this overview does not replace the current original standard. For safety-relevant or tolerance-critical applications, we recommend verifying dimensions against the applicable standard (DIN/ISO/BS/ASME).

Simple Pitch Diameter or Pitch Diameter?

The two terms are often used interchangeably, but they describe different things. The difference decides whether a thread will actually mate – which is why it matters in thread inspection.

Simple pitch diameter

The purely geometric value at a single measuring position – what a two-point measurement gives you directly, for example using the three-wire method or a thread micrometer. Pitch and flank angle deviations are not included.

Virtual pitch diameter

Also called the functional or effective pitch diameter. It converts pitch and flank angle deviations into diameter equivalents and adds them in, describing the thread as it actually behaves when mating.

On an external thread, form and pitch errors increase the effective size: the virtual pitch diameter lies above the simple pitch diameter. On an internal thread it is the other way round. A thread can therefore have a perfectly acceptable simple pitch diameter and still fail to mate if the pitch or flank angle deviates too far.

In gauge inspection this follows the Taylor principle: the GO gauge checks over the full engagement length and therefore captures the virtual pitch diameter, while the NO-GO gauge engages only a few turns and targets the simple pitch diameter.

The table and calculator on this page consistently give the theoretical pitch diameter of the nominal profile – neither measured values nor functional sizes.

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