M2.5 × 0.45 M profile External Thread Specifications

M2.5x0.45-6g

ASMESTD: ASME B1.13MSOURCE: Table 14 · p. 26TYPE: External (bolt/screw)CLASS: 6gSERIES: M coarse (Table 4)1st choice (Table 6, p. 9) · standard size

Major diameter

2.480 – 2.380

max – min

Pitch diameter

2.188 – 2.117

max – min

Minor diameter

1.993 – 1.840

max – min (min is a reference value)

Fundamental deviation

es −0.020

pitch 0.45 mm · position g

Thread profile

M2.5x0.45-6g: 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

Dimension	Basic	Max	Min	Tolerance
Major diameter dOutside diameter over the crests	2.500	2.480	2.380	0.100
Pitch diameter d2Where thread and groove widths are equal; sets the fit	2.208	2.188	2.117	0.071
Minor diameter, flat root d1Max d1 (flat form); min = d3 of the rounded form, for reference	2.013	1.993	1.840ref.	0.153ref.
Rounded-form minor diameter d3d3 max and d3 min; used for tools and gaging		1.990ref.	1.840ref.
Deviations, pitch diameter es / eiUpper and lower deviation from the basic pitch diameter (Fig. 4)	—	−0.020	−0.091	—
Deviations, major diameter es / eiCrest diameter	—	−0.020	−0.120	—

Dimensions in millimetres. Values are those of the standard (ASME B1.13M); calculated cells follow the standard’s formulas. 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: 0.020 mmOver the length of engagement
Equivalent change in functional diameter δd2: 0.036 mmHalf the pitch diameter tolerance
Allowable half-angle variation ±δα: 3° 05′ Each 30° flank angle
Length of engagement, normal LE: 1.3 – 3.8 mmShort up to / long over: see all values

Notes

Normal tolerance, small allowance (para 5.5.1(a)); the usual bolt class, ~ inch 2A.

Mates

M2.5x0.45-6g 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

→ M2.5 × 0.35 mm → M2.2 × 0.45 mm → M3 × 0.35 mm → M2.5 × 0.45 internal → ISO metric M2.5x0.45 external

All values for M2.5x0.45-6gevery column of the workbook row

All values of the workbook row M2.5x0.45-6g
Designation	M2.5x0.45-6g
Alternate designation (all capitals, para 7.2.3)	M2.5X0.45-6G EXT
Pitch in designation	0.45
Thread form	M
Series	Coarse
Series name	Standard coarse pitch series (Table 4)
External / internal	External
Class	6g
Nominal size	M2.5
Pitch P (mm)	0.45
Basic major dia D, d (mm)	2.500
Size category	1st choice (Table 6, p. 9) · standard size
Source table	Table 14
Printed page	26
Thread type	M coarse (Table 4)
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)	-0.020
Fundamental deviation es / EI, crest dia (mm)	-0.020
Allowance \|es\| / EI (mm)	0.020
Major dia max (mm)	2.480
Major dia min (mm)	2.380
Major dia tolerance Td (mm)	0.100
Major dia status	Toleranced (d max, d min)
Basic pitch dia D2, d2 (mm)	2.208
Pitch dia max (mm)	2.188
Pitch dia min (mm)	2.117
PD tolerance Td2 / TD2 (mm)	0.071
Basic minor dia D1, d1 (mm)	2.013
Minor dia max (mm)	1.993
Minor dia min (mm)	1.840
Minor dia tolerance TD1 (mm)	0.153
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)	1.993
Min minor dia, rounded form d3 (mm, reference)	1.840
Max minor dia, rounded form d3, para 9.3.2(f) (mm)	1.990
Upper deviation, pitch dia es / ES (mm)	-0.020
Lower deviation, pitch dia ei / EI (mm)	-0.091
Upper deviation, crest dia (mm)	-0.020
Lower deviation, crest dia (mm)	-0.120
LE short, up to (mm)	1.3
LE normal, over (mm)	1.3
LE normal, up to and incl. (mm)	3.8
LE long, over (mm)	3.8
LE source	Table 7
Lead variation ± (mm)	0.020
Equivalent change in functional dia (mm)	0.036
Lead values source	Table 17, p. 47
Half-angle variation ±	3° 05′
Half-angle source	Table 18
Lead angle at basic PD (deg)	3.7117
Lead angle (deg min)	3° 43′
Tensile stress area As (mm²)	3.391
Thread angle (deg)	60
Flank angle (deg)	30
Sharp V height H (mm)	0.389711
Thread height h = 5H/8 (mm)	0.243570
Crest flat (mm)	0.056250
Root flat (mm)	0.112500
Sweep cut: start diameter (mm)	2.480000
Sweep cut: tip diameter (mm)	1.993000
Sweep cut: depth (mm)	0.243500
Sweep cut: profile width at start diameter (mm)	0.393750
Crest flat as modelled (mm)	0.056414
Inch (App. C): allowance (in.)	0.00079
Inch (App. C): major dia max (in.)	0.09764
Inch (App. C): major dia min (in.)	0.09370
Inch (App. C): pitch dia max (in.)	0.08614
Inch (App. C): pitch dia min (in.)	0.08335
Inch (App. C): PD tolerance (in.)	0.00280
Inch (App. C): minor dia max (in.)	0.07846
Inch (App. C): d3 min / D max, reference (in.)	0.07244
Inch (App. C): pitch (in.)	0.01772
Inch (App. C): printed page	54
Check against formulas	OK: all 8 printed Table 14 values agree with the formulas.
Notes	Normal tolerance, small allowance (para 5.5.1(a)); the usual bolt class, ~ inch 2A.

ASME B1.13M: Metric Screw Threads: M Profile. Source: workbook data (2026-10-10). Confirm against your licensed copy of the standard before use.