logo9  MARYLAND METRICS -- THREAD IDENTIFICATION CHART SECTION (A):
FOR MAJOR DIAMETERS FROM 7.894 mm to 64 mm + Electrical thread to 110 mm
Continuation: (Also see the IMPORTANT notes at the bottom of this table.)

BASIC MAJOR DIAMETER NOMINAL DIAMETER METRIC STD. REF. METRIC -- PITCH in mm NOMINAL DIAMETER AMERICAN AMERICAN -- PITCH in THREADS per Inch SPECIAL USE NOTES* NOMINAL DIAMETER BRITISH BRITISH -- PITCH in THREADS per Inch
Inch mm mm . COARSE FINE M TAPER FRACTIONS UNC UNF UNEF NPT 8UN *See table SD FRACTIONS BSW BSF BSPF BSPT
0.3108 7.894 . . . . . 1/16 . . . 27 . . . . . BSPP .
0.3125 7.94 . . . . . 5/16 18 24 32 . . 24(C-J) 24(SAE-F) 5/16 18 22 . .
0.3150 8.00 8 I D 1.25 0.5,0.75,1 1 . . . . . . . . . . . .
0.3543 9.00 9 III D 1.25 0.75,1 . . . . . . . . . . . . .
0.3750 9.53 . . . . . 3/8 16 24 32 . . 24(SAE C-J) 3/8 16 20 . .
0.3830 9.73 . . . . . . . . . . . . 1/8 . . 28 28
0.3937 10.00 10 I D 1.5 0.75,1,1.25 1 . . . . . . . . . . . .
0.4044 10.271 . . . . . 1/8 . . . 27 . . . . . . .
0.4331 11.00 11 III D 1.5 0.75,1,1.25 . . . . . . . . . . . . .
0.4375 11.11 . . . . . 7/16 14 20 28 . . 24(C) 20(SAE J-F) 7/16 14 18 . .
0.4724 12.00 12 I D 1.75 1,1.25,1.5 1.5 . . . . . . . . . . . .
0.5000 12.70 . . . . . 1/2 13 20 28 . . 24(C) 20(SAE J-F) 1/2 12 16 . .
0.5180 13.16 . . . . . . . . . . . . 1/4 . . 19 19
0.5343 13.571 . . . . . . . . . 18 . . . . . . .
0.5512 14.00 14 II D 2 1,1.25,1.5 . . . . . . . . . . . . .
0.5625 14.29 . . . . . 9/16 12 18 24 . . 24(C) 18(SAE-J) 9/16 12 16 . .
0.5906 15.00 15 III D . 1,1.5 . . . . . . . . . . . . .
0.6250 15.88 . . . . . 5/8 11 18 24 . . 24(C) 18(SAE-F) 5/8 11 14 . .
0.6299 16.00 16 I D 2 1,1.5 1.5 . . . . . . . . . . . .
0.6560 16.662 . . . . . . . . . . . . 3/8 . . 19 19
0.6693 17.00 17 III D . 1,1.5 . . . . . . . . . . . . .
0.6714 17.054 . . . . . 3/8 . . . 18 . . . . . . .
0.6875 17.46 . . . . . 11/16 . . 24 . . 20(C) 18(SAE-F) 11/16 11 14 . .
0.7087 18.00 18 II D 2.5 1,1.5,2 1.5 . . . . . . . . . . . .
0.7500 19.05 . . . . . 3/4 10 16 20 . . 16(SAE-J-F) 3/4 10 12 . .
0.7874 20.00 20 I D 2.5 1,1.5,2 1.5 . . . . . . . . . . . .
0.8125 20.64 . . . . . 13/16 . . 20 . . 18(C) 13/16 10 12 . .
0.8250 20.955 . . . . . . . . . . . . 1/2 . . 14 14
0.8356 21.222 . . . . . 1/2 . . . 14 . . . . . . .
0.8661 22.00 22 II D 2.5 1,1.5,2 1.5 . . . . . . . . . . . .
0.8750 22.23 . . . . . 7/8 9 14 20 . . 14(SAE-F-J) 7/8 9 11 . .
0.9020 22.911 . . . . . . . . . . . . 5/8 . . 14 14
0.9375 23.81 . . . . . 15/16 . . 20 . . 20(C-J) 16(SAE) 15/16 9 . . .
0.9449 24.00 24 I D 3 1,1.5,2 . . . . . . . . . . . . .
0.9843 25.00 25 III D . 1,1.5,2 . . . . . . . . . . . . .
1.0000 25.40 . . . . . 1 8 12 20 . 8 18(C) 14(NF) 1 8 10 . .
1.0236 26.00 26 III D . 1.5 1.5 . . . . . . . . . . . .
1.0410 26.441 . . . . . . . . . . . . 3/4 . . 14 14
1.0460 26.568 . . . . . 3/4 . . . 14 . . . . . . .
1.0625 26.99 . . . . . 1 1/16 . . 18 . 8 14(F) 12(SAE-J) . . . . .
1.0630 27.00 27 II D 3 1,1.5,2 . . . . . . . . . . . . .
1.1024 28.00 28 III D . 1,1.5,2 . . . . . . . . . . . . .
1.1250 28.58 . . . . . 1 1/8 7 12 18 . 8 18(C) 1 1/8 7 9 . .
1.1811 30.00 30 I D 3.5 1,1.5,2,3 . . . . . . . . . . . . .
1.1875 30.16 . . . . . 1 3/16 . . 18 . 8 12(SAE-J) . . . . .
1.1890 30.20 . . . . . . . . . . . . 7/8 . . 14 14
1.2500 31.75 . . . . . 1 1/4 7 12 18 . 8 12(SAE) 1 1/4 7 9 . .
1.2598 32.00 32 III D . 1.5,2 . . . . . . . . . . . . .
1.2992 33.00 33 II D 3.5 1.5,2,3 . . . . . . . . . . . . .
1.3328 33.228 . . . . . 1 . . . 11 1/2 . . . . . . .
1.3090 33.249 . . . . . . . . . . . . 1 . . 11 11
1.3125 33.34 . . . . . 1 5/16 . . 18 . 8 12(SAE-J) . . . . .
1.3750 34.93 . . . . . 1 3/8 6 12 18 . 8 . 1 3/8 6 8 . .
1.3780 35.00 35 III D . 1.5 . . . . . . . SEE TABLE . . . . .
1.4173 36.00 36 I D 4 1.5,2,3 . . . . . . . SD . . . . .
1.4375 36.51 . . . . . 1 7/16 . . 18 . 8 FOR . . . . .
1.4920 37.897 . . . . . . . . . . . SPECIAL 1 1/8 . . 11 .
1.4961 38.00 38 III D . 1.5 . . . . . . . USE . . . . .
1.5000 38.10 . . . . . 1 1/2 6 12 18 . 8 DEFINITIONS 1 1/2 6 8 . .
1.5354 39.00 39 II D 4 1.5,2,3 . . . . . . . . . . . . .
1.5625 39.69 . . . . . 1 9/16 . . 18 . 8 . . . . . .
1.5748 40.00 40 III D . 1.5,2,3 . . . . . . . . . . . . .
1.6250 41.28 . . . . . 1 5/8 . . 18 . 8 12(SAE-J) 1 5/8 5 8 . .
1.6500 41.91 . . . . . . . . . . . . 1 1/4 . . 11 11
1.6535 41.99 42 I D 4.5 1.5,2,3,4 . . . . . . . . . . . . .
1.6600 42.16 . . . . . 1 1/4 . . . 11 1/2 . . . . . . .
1.6875 42.86 . . . . . 1 11/16 . . 18 . 8 . . . . . .
1.7450 44.32 . . . . . . . . . . . . 1 3/8 . . 11 .
1.7500 44.45 . . 16 . . 1 3/4 5 . 16 . 8 . 1 3/4 5 7 . .
1.7717 45.00 45 II D 4.5 1.5,2,3,4 . . . . . . . . . . . . .
1.8750 47.63 . . . . . 1 7/8 . . . . 8 12(SAE-J) 1 7/8 4 1/2 . . .
1.8820 47.802 . . . . . . . . . . . . 1 1/2 . . 11 11
1.8898 48.00 48 I D 5 1.5,2,3,4 . . . . . . . . . . . . .
1.8919 48.054 . . . . . 1 1/2 . . . 11 1/2 . . . . . . .
1.9685 50.00 50 III D . 1.5,2,3 . . . . . . . . . . . . .
2.0000 50.80 . . . . . 2 4 1/2 . 16 . 8 . 2 4 1/2 7 . .
2.0472 52.00 52 II D 5 1.5,2,3,4 . . . . . . . . . . . . .
2.1654 55.00 55 III D . 1.5,2,3,4 . . . . . . . . . . . . .
2.2047 56.00 56 I D 5.5 1.5,2,3,4 . . . . . . . . . . . . .
2.2500 57.15 . . . . . 2 1/4 4 1/2 . . . 8 . 2 1/4 4 6 . .
2.2835 58.00 58 III D . 1.5,2,3,4 . . . . . . . . . . . . .
2.3470 59.613 . . . . . . . . . . . . 2 . . 11 11
2.3622 60.00 60 II D 5.5 1.5,2,3,4 . . . . . . . . . . . . .
2.3658 60.094 . . . . . 2 . . . 11 1/2 . . . . . . .
2.4409 62.00 62 III D . 1.5,2,3,4 . . . . . . . . . . . . .
2.5000 63.50 . . . . . 2 1/2 4 . . . 8 12(SAE-J) 2 1/2 4 6 . .
2.5197 64.00 64 I D 6 1.5,2,3,4 . . . . . . . . . . . . .
Metric Electrical thread
2.4803 63.00 63 . . 1.5 . . . . . . . E . . . . .
2.9528 75.00 75 . . 1.5 . . . . . . . E . . . . .
3.1496 80.00 80 . . 2 . . . . . . . E . . . . .
3.3465 85.00 85 . . 2 . . . . . . . E . . . . .
3.5433 90.00 90 . . 2 . . . . . . . E . . . . .
3.937 100.00 100 . . 2, 3 . . . . . . . E . . . . .
4.3307 110.00 110 . . 2 . . . . . . . E . . . . .
  1. The British thread system is fractionally based, but all thread vee angles are different than the American fractionally or decimally based threads. Most thread per inch values are different than in the American System.
  2. Taper pipe thread major diameters are measured at the guage point.
  3. (H)= BSPT copper pipe thread.
  4. Dimensions within ( ) in the M FINE column are obsolete French or Japanese threads.
  5. Dimensions within ( ) in the BSW column are obsolete British coarse threads.
  6. The 6.3 mm dimension; marked GM is an obsolete General Motors thread.

TABLE (SD) -- SPECIAL USE THREAD DEFINITIONS

C = Compression fittings
J = JIC 37 degree Flare fittings
F = JIC 45 degree Flare fittings
SAE = SAE straight thread
NF = National Fine thread
E = Electrical thread

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