M3 × 0.5 M profile External Thread Specifications

M3x0.5-6g

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

2.980 – 2.874

max – min

Pitch diameter

2.655 – 2.580

max – min

Minor diameter

2.438 – 2.272

max – min (min is a reference value)

Fundamental deviation

es −0.020

pitch 0.5 mm · position g

Thread profile

M3x0.5-6g: 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

Dimension	Basic	Max	Min	Tolerance
Major diameter dOutside diameter over the crests	3.000	2.980	2.874	0.106
Pitch diameter d2Where thread and groove widths are equal; sets the fit	2.675	2.655	2.580	0.075
Minor diameter, flat root d1Max d1 (flat form); min = d3 of the rounded form, for reference	2.459	2.438	2.272ref.	0.166ref.
Rounded-form minor diameter d3d3 max and d3 min; used for tools and gaging		2.435ref.	2.272ref.
Deviations, pitch diameter es / eiUpper and lower deviation from the basic pitch diameter (Fig. 4)	—	−0.020	−0.095	—
Deviations, major diameter es / eiCrest diameter	—	−0.020	−0.126	—

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: 0.022 mmOver the length of engagement
Equivalent change in functional diameter δd2: 0.038 mmHalf the pitch diameter tolerance
Allowable half-angle variation ±δα: 2° 55′ Each 30° flank angle
Length of engagement, normal LE: 1.5 – 4.5 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

M3x0.5-6g 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

→ M3 × 0.35 mm → M2.5 × 0.45 mm → M3.5 × 0.35 mm → M3 × 0.5 internal → ISO metric M3x0.5 external

All values for M3x0.5-6gevery column of the workbook row

All values of the workbook row M3x0.5-6g
Designation	M3x0.5-6g
Alternate designation (all capitals, para 7.2.3)	M3X0.5-6G EXT
Pitch in designation	0.5
Thread form	M
Series	Coarse
Series name	Standard coarse pitch series (Table 4)
External / internal	External
Class	6g
Nominal size	M3
Pitch P (mm)	0.50
Basic major dia D, d (mm)	3.000
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)	2.980
Major dia min (mm)	2.874
Major dia tolerance Td (mm)	0.106
Major dia status	Toleranced (d max, d min)
Basic pitch dia D2, d2 (mm)	2.675
Pitch dia max (mm)	2.655
Pitch dia min (mm)	2.580
PD tolerance Td2 / TD2 (mm)	0.075
Basic minor dia D1, d1 (mm)	2.459
Minor dia max (mm)	2.438
Minor dia min (mm)	2.272
Minor dia tolerance TD1 (mm)	0.166
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)	2.438
Min minor dia, rounded form d3 (mm, reference)	2.272
Max minor dia, rounded form d3, para 9.3.2(f) (mm)	2.435
Upper deviation, pitch dia es / ES (mm)	-0.020
Lower deviation, pitch dia ei / EI (mm)	-0.095
Upper deviation, crest dia (mm)	-0.020
Lower deviation, crest dia (mm)	-0.126
LE short, up to (mm)	1.5
LE normal, over (mm)	1.5
LE normal, up to and incl. (mm)	4.5
LE long, over (mm)	4.5
LE source	Table 7
Lead variation ± (mm)	0.022
Equivalent change in functional dia (mm)	0.038
Lead values source	Table 17, p. 47
Half-angle variation ±	2° 55′
Half-angle source	Table 18
Lead angle at basic PD (deg)	3.4049
Lead angle (deg min)	3° 24′
Tensile stress area As (mm²)	5.031
Thread angle (deg)	60
Flank angle (deg)	30
Sharp V height H (mm)	0.433013
Thread height h = 5H/8 (mm)	0.270633
Crest flat (mm)	0.062500
Root flat (mm)	0.125000
Sweep cut: start diameter (mm)	2.980000
Sweep cut: tip diameter (mm)	2.438000
Sweep cut: depth (mm)	0.271000
Sweep cut: profile width at start diameter (mm)	0.437500
Crest flat as modelled (mm)	0.062361
Inch (App. C): allowance (in.)	0.00079
Inch (App. C): major dia max (in.)	0.11732
Inch (App. C): major dia min (in.)	0.11315
Inch (App. C): pitch dia max (in.)	0.10453
Inch (App. C): pitch dia min (in.)	0.10157
Inch (App. C): PD tolerance (in.)	0.00295
Inch (App. C): minor dia max (in.)	0.09598
Inch (App. C): d3 min / D max, reference (in.)	0.08945
Inch (App. C): pitch (in.)	0.01969
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.