M45 × 4.5 M profile External Thread Specifications
M45x4.5-6g
ASMESTD: ASME B1.13MSOURCE: Calculated (para 9.2(b): Tables 7, 9-13 and para 9.3)TYPE: External (bolt/screw)CLASS: 6gSERIES: M ISO 261 other sizes (Table 6)2nd choice (Table 6, p. 10)calculated, not printed in the standard
Major diameter
44.937 – 44.437
max – min
Pitch diameter
42.014 – 41.778
max – min
Minor diameter
40.065 – 39.006
max – min (min is a reference value)
Fundamental deviation
es −0.063
pitch 4.5 mm · position g
Thread profile
M45x4.5-6g: solid line = maximum material profile, dashed = minimum material, hatched = tolerance zone (Figs. 8 and 9), grey dashed = basic profile (Fig. 1). Drawn to scale; values in mm, diameters shortened.
Limits of size, class 6g
calculated, not printed in the standard.
| Dimension | Basic | Max | Min | Tolerance |
|---|---|---|---|---|
| Major diameter dOutside diameter over the crests | 45.000 | 44.937 | 44.437 | 0.500 |
| Pitch diameter d2Where thread and groove widths are equal; sets the fit | 42.077 | 42.014 | 41.778 | 0.236 |
| Minor diameter, flat root d1Max d1 (flat form); min = d3 of the rounded form, for reference | 40.129 | 40.065 | 39.006ref. | 1.059ref. |
| Rounded-form minor diameter d3d3 max and d3 min; used for tools and gaging | 39.878ref. | 39.006ref. | ||
| Deviations, pitch diameter es / eiUpper and lower deviation from the basic pitch diameter (Fig. 4) | — | −0.063 | −0.299 | — |
| Deviations, major diameter es / eiCrest diameter | — | −0.063 | −0.563 | — |
Dimensions in millimetres. Values are those of the standard (ASME B1.13M); this row is calculated. Where the standard prints a value that differs from its formula, the printed value is shown with a note.
Tolerance zones relative to the basic size, mm (Fig. 4)
Lead, flank angle and length of engagement
- Allowable lead variation ±δP
- 0.068 mmOver the length of engagement
- Equivalent change in functional diameter δd2
- 0.118 mmHalf the pitch diameter tolerance
- Allowable half-angle variation ±δα
- 1° 00′ Each 30° flank angle
- Length of engagement, normal LE
- 21.0 – 63.0 mmShort up to / long over: see all values
Lead source: calculated, para 10.1.5; half-angle source: Table 18; length of engagement: Table 7
Notes
- Normal tolerance, small allowance (para 5.5.1(a)); the usual bolt class, ~ inch 2A.
Mates
M45x4.5-6g screws into a thread of the same standard at the same size and pitch. The standard mating internal thread is class 6H. Check the fit with the standard pair →
Working out the mating options…
Different pitch or a different thread family never mate; the fit check runs over both tolerance zones.
Related thread sizes
Same diameter other pitch, and neighbouring sizes
All values for M45x4.5-6gevery column of the workbook row
| Designation | M45x4.5-6g |
|---|---|
| Alternate designation (all capitals, para 7.2.3) | M45X4.5-6G EXT |
| Pitch in designation | 4.5 |
| Thread form | M |
| Series | Coarse |
| Series name | ISO 261 coarse pitch, not a B1.13M standard size (Table 6) |
| External / internal | External |
| Class | 6g |
| Nominal size | M45 |
| Pitch P (mm) | 4.50 |
| Basic major dia D, d (mm) | 45.000 |
| Size category | 2nd choice (Table 6, p. 10) |
| Source table | Calculated (para 9.2(b): Tables 7, 9-13 and para 9.3) |
| Thread type | M ISO 261 other sizes (Table 6) |
| Tolerance position, pitch dia | g |
| Tolerance grade, pitch dia | 6 |
| Tolerance position, crest dia | g |
| Tolerance grade, crest dia | 6 |
| Fundamental deviation es / EI, pitch dia (mm) | -0.063 |
| Fundamental deviation es / EI, crest dia (mm) | -0.063 |
| Allowance |es| / EI (mm) | 0.063 |
| Major dia max (mm) | 44.937 |
| Major dia min (mm) | 44.437 |
| Major dia tolerance Td (mm) | 0.500 |
| Major dia status | Toleranced (d max, d min) |
| Basic pitch dia D2, d2 (mm) | 42.077 |
| Pitch dia max (mm) | 42.014 |
| Pitch dia min (mm) | 41.778 |
| PD tolerance Td2 / TD2 (mm) | 0.236 |
| Basic minor dia D1, d1 (mm) | 40.129 |
| Minor dia max (mm) | 40.065 |
| Minor dia min (mm) | 39.006 |
| Minor dia tolerance TD1 (mm) | 1.059 |
| Minor dia status | d1 max toleranced (flat form, para 9.3.2(e)); min is d3 min of the rounded form, for reference (Table 14 note 4) |
| Max minor dia, flat form d1 (mm) | 40.065 |
| Min minor dia, rounded form d3 (mm, reference) | 39.006 |
| Max minor dia, rounded form d3, para 9.3.2(f) (mm) | 39.878 |
| Upper deviation, pitch dia es / ES (mm) | -0.063 |
| Lower deviation, pitch dia ei / EI (mm) | -0.299 |
| Upper deviation, crest dia (mm) | -0.063 |
| Lower deviation, crest dia (mm) | -0.563 |
| LE short, up to (mm) | 21.0 |
| LE normal, over (mm) | 21.0 |
| LE normal, up to and incl. (mm) | 63.0 |
| LE long, over (mm) | 63.0 |
| LE source | Table 7 |
| Lead variation ± (mm) | 0.068 |
| Equivalent change in functional dia (mm) | 0.118 |
| Lead values source | calculated, para 10.1.5 |
| Half-angle variation ± | 1° 00′ |
| Half-angle source | Table 18 |
| Lead angle at basic PD (deg) | 1.9497 |
| Lead angle (deg min) | 1° 57′ |
| Tensile stress area As (mm²) | 1306.005 |
| Thread angle (deg) | 60 |
| Flank angle (deg) | 30 |
| Sharp V height H (mm) | 3.897114 |
| Thread height h = 5H/8 (mm) | 2.435697 |
| Crest flat (mm) | 0.562500 |
| Root flat (mm) | 1.125000 |
| Sweep cut: start diameter (mm) | 44.937000 |
| Sweep cut: tip diameter (mm) | 40.065000 |
| Sweep cut: depth (mm) | 2.436000 |
| Sweep cut: profile width at start diameter (mm) | 3.937500 |
| Crest flat as modelled (mm) | 0.562405 |
| Check against formulas | Calculated with the standard's formulas; no printed limits for this designation. |
| Notes | Normal tolerance, small allowance (para 5.5.1(a)); the usual bolt class, ~ inch 2A. |
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ASME B1.13M: Metric Screw Threads: M Profile. Source: workbook data (2026-10-10). Confirm against your licensed copy of the standard before use.