M2.5 × 0.35 M profile External Thread Specifications

M2.5x0.35-6g

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)1st choice (Table 6, p. 9)calculated, not printed in the standard
Major diameter
2.481 – 2.396
max – min
Pitch diameter
2.254 – 2.191
max – min
Minor diameter
2.102 – 1.975
max – min (min is a reference value)
Fundamental deviation
es −0.019
pitch 0.35 mm · position g

Thread profile

M2.5x0.35-6g: external M profile with its tolerance zone, drawn to scaled = 2.500d2 = 2.273d1 = 2.121P = 0.3560°30°crest P/8 = 0.043750root P/4 = 0.087500Major dia zone (crest)2.481 – 2.396 Td 0.085Pitch dia zone (flanks)2.254 – 2.191 Td2 0.063Root: d1 max / d3 min (ref.)2.102 – 1.975Fundamental deviationes = −0.019 (allowance)H/80.0378893H/80.113666H/40.075777h = 5H/80.189443H0.303109thread axis, 1.250 mm below the major radius (diameters shortened)MALE · external thread · M2.5x0.35-6g

M2.5x0.35-6g: 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.

DimensionBasicMaxMinTolerance
Major diameter dOutside diameter over the crests2.5002.4812.3960.085
Pitch diameter d2Where thread and groove widths are equal; sets the fit2.2732.2542.1910.063
Minor diameter, flat root d1Max d1 (flat form); min = d3 of the rounded form, for reference2.1212.1021.975ref.0.127ref.
Rounded-form minor diameter d3d3 max and d3 min; used for tools and gaging2.101ref.1.975ref.
Deviations, pitch diameter es / eiUpper and lower deviation from the basic pitch diameter (Fig. 4)—−0.019−0.082—
Deviations, major diameter es / eiCrest diameter—−0.019−0.104—

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)

Tolerance zones relative to the basic sizezero line = basic size+ above · − belowd2es −0.019ei −0.082male pitch dia 6ges −0.019des −0.019ei −0.104male major dia (crest)es −0.019

Lead, flank angle and length of engagement

Allowable lead variation ±δP
0.018 mmOver the length of engagement
Equivalent change in functional diameter δd2
0.032 mmHalf the pitch diameter tolerance
Allowable half-angle variation ±δα
3° 30′ Each 30° flank angle
Length of engagement, normal LE
0.8 – 2.6 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

M2.5x0.35-6g 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 × 0.45 mm→ M2.2 × 0.45 mm→ M3 × 0.35 mm→ M2.5 × 0.35 internal→ ISO metric M2.5x0.35 external
All values for M2.5x0.35-6gevery column of the workbook row
All values of the workbook row M2.5x0.35-6g
DesignationM2.5x0.35-6g
Alternate designation (all capitals, para 7.2.3)M2.5X0.35-6G EXT
Pitch in designation0.35
Thread formM
SeriesFine
Series nameISO 261 fine pitch, not a B1.13M standard size (Table 6)
External / internalExternal
Class6g
Nominal sizeM2.5
Pitch P (mm)0.35
Basic major dia D, d (mm)2.500
Size category1st choice (Table 6, p. 9)
Source tableCalculated (para 9.2(b): Tables 7, 9-13 and para 9.3)
Thread typeM ISO 261 other sizes (Table 6)
Tolerance position, pitch diag
Tolerance grade, pitch dia6
Tolerance position, crest diag
Tolerance grade, crest dia6
Fundamental deviation es / EI, pitch dia (mm)-0.019
Fundamental deviation es / EI, crest dia (mm)-0.019
Allowance |es| / EI (mm)0.019
Major dia max (mm)2.481
Major dia min (mm)2.396
Major dia tolerance Td (mm)0.085
Major dia statusToleranced (d max, d min)
Basic pitch dia D2, d2 (mm)2.273
Pitch dia max (mm)2.254
Pitch dia min (mm)2.191
PD tolerance Td2 / TD2 (mm)0.063
Basic minor dia D1, d1 (mm)2.121
Minor dia max (mm)2.102
Minor dia min (mm)1.975
Minor dia tolerance TD1 (mm)0.127
Minor dia statusd1 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)2.102
Min minor dia, rounded form d3 (mm, reference)1.975
Max minor dia, rounded form d3, para 9.3.2(f) (mm)2.101
Upper deviation, pitch dia es / ES (mm)-0.019
Lower deviation, pitch dia ei / EI (mm)-0.082
Upper deviation, crest dia (mm)-0.019
Lower deviation, crest dia (mm)-0.104
LE short, up to (mm)0.8
LE normal, over (mm)0.8
LE normal, up to and incl. (mm)2.6
LE long, over (mm)2.6
LE sourceTable 7
Lead variation ± (mm)0.018
Equivalent change in functional dia (mm)0.032
Lead values sourcecalculated, para 10.1.5
Half-angle variation ±3° 30′
Half-angle sourceTable 18
Lead angle at basic PD (deg)2.8060
Lead angle (deg min)2° 48′
Tensile stress area As (mm²)3.704
Thread angle (deg)60
Flank angle (deg)30
Sharp V height H (mm)0.303109
Thread height h = 5H/8 (mm)0.189443
Crest flat (mm)0.043750
Root flat (mm)0.087500
Sweep cut: start diameter (mm)2.481000
Sweep cut: tip diameter (mm)2.102000
Sweep cut: depth (mm)0.189500
Sweep cut: profile width at start diameter (mm)0.306250
Crest flat as modelled (mm)0.043941
Check against formulasCalculated with the standard's formulas; no printed limits for this designation.
NotesNormal tolerance, small allowance (para 5.5.1(a)); the usual bolt class, ~ inch 2A.

Related tools

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