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GMT CNC Machining Feeds and Speeds Calculator



Select which GMT product you are using:

OR enter the values below:

Tool diameter (inches):
Number of Teeth/Flutes:

Calculate: Spindle Speed in Revolutions per Minute (RPM)

Cutting speed (SFM) Tool diameter Spindle speed (RPM)
÷ x 12 ÷ π =

Calculate: Cutting Speed in Surface Feet per Minute (SFM)

Spindle speed (RPM) Tool diameter Cutting speed (SFM)
x x π ÷ 12 =

Calculate: Inches per Minute Feedrate (IPM)

Spindle speed (RPM) Feed per tooth (IPT) # of Teeth/Flutes Inches per Minute Feedrate (IPM)
x x =






 

GMT Tap Drill Chart


Tap Drill Reference Chart

Aluminum, Brass & Plastics 75% Thread Stainless Steel, Steels & Iron 50% Thread Clearance Hole Drills - Close Fit Clearance Hole Drills - Free Fit
No. or Dia. # Threads Per Inch Minor Diameter Major Diameter Drill Size Decimal Equiv. Drill Size Decimal Equiv. Drill Size Decimal Equiv. Drill Size Decimal Equiv.
0 80 0.0447 0.0600 3/64 0.0469 55 0.0520 52 0.0635 50 0.0700
1 64 0.0538 0.0730 53 0.0595 1/16 0.0625 48 0.0760 46 0.0810
1 72 0.0560 0.0730 53 0.0595 52 0.0635 48 0.0760 46 0.0810
2 56 0.0641 0.0860 50 0.0700 49 0.0730 43 0.0890 41 0.0960
2 64 0.0668 0.0860 50 0.0700 48 0.0760 43 0.0890 41 0.0960
3 48 0.0734 0.0990 47 0.0785 44 0.0860 37 0.1040 35 0.1100
3 56 0.0771 0.0990 45 0.0820 43 0.0890 37 0.1040 35 0.1100
4 40 0.0813 0.1120 43 0.0890 41 0.0960 32 0.1160 30 0.1285
4 48 0.0864 0.1120 42 0.0935 40 0.0980 32 0.1160 30 0.1285
5 40 0.0943 0.1250 38 0.1015 7/64 0.1094 30 0.1285 29 0.1360
5 44 0.0971 0.1250 37 0.1040 35 0.1100 30 0.1285 29 0.1360
6 32 0.0997 0.1380 36 0.1065 32 0.1160 27 0.1440 25 0.1495
6 40 0.1073 0.1380 33 0.1130 31 0.1200 27 0.1440 25 0.1495
8 32 0.1257 0.1640 29 0.1360 27 0.1440 18 0.1695 16 0.1770
8 36 0.1299 0.1640 29 0.1360 26 0.1470 18 0.1695 16 0.1770
10 24 0.1389 0.1900 25 0.1495 20 0.1610 9 0.1960 7 0.2010
10 32 0.1517 0.1900 21 0.1590 18 0.1695 9 0.1960 7 0.2010
12 24 0.1649 0.2160 16 0.1770 12 0.1890 2 0.2210 1 0.2280
12 28 0.1722 0.2160 14 0.1820 10 0.1935 2 0.2210 1 0.2280
12 32 0.1777 0.2160 13 0.1850 9 0.1960 2 0.2210 1 0.2280
1/4 20 0.1887 0.2500 7 0.2010 7/32 0.2188 F 0.2570 H 0.2660
1/4 28 0.2062 0.2500 3 0.2130 1 0.2280 F 0.2570 H 0.2660
1/4 32 0.2117 0.2500 7/32 0.2188 1 0.2280 F 0.2570 H 0.2660
5/16 18 0.2443 0.3125 F 0.2570 J 0.2770 P 0.3230 Q 0.3320
5/16 24 0.2614 0.3125 I 0.2720 9/32 0.2812 P 0.3230 Q 0.3320
5/16 32 0.2742 0.3125 9/32 0.2812 L 0.2900 P 2.3230 Q 0.3320
3/8 16 0.2983 0.3750 5/16 0.3125 Q 0.3320 W 0.3860 X 0.3970
3/8 24 0.3239 0.3750 Q 0.3320 S 0.3480 W 0.3860 X 0.3970
3/8 32 0.3367 0.3750 11/32 0.3438 T 0.3580 W 0.3860 X 0.3970
7/16 14 0.3499 0.4375 U 0.3680 25/64 0.3906 29/64 0.4531 15/32 0.4687
7/16 20 0.3762 0.4375 25/64 0.3906 13/32 0.4062 29/64 0.4531 15/32 0.4687
7/16 28 0.3937 0.4375 Y 0.4040 Z 0.4130 29/64 0.4531 15/32 0.4687
1/2 13 0.4056 0.5000 27/64 0.4219 29/64 0.4531 33/64 0.5156 17/32 0.5312
1/2 20 0.4386 0.5000 29/64 0.4531 15/32 0.4688 33/64 0.5156 17/32 0.5312
1/2 28 0.4562 0.5000 15/32 0.4688 15/32 0.4688 33/64 0.5156 17/32 0.5312
9/16 12 0.4603 0.5625 31/64 0.4844 33/64 0.5156 37/64 0.5781 19/32 0.5938
9/16 18 0.4943 0.5625 33/64 0.5156 17/32 0.5312 37/64 0.5781 19/32 0.5938
9/16 24 0.5114 0.5625 33/64 0.5156 17/32 0.5312 37/64 0.5781 19/32 0.5938
5/8 11 0.5135 0.6250 17/32 0.5312 9/16 0.5625 41/64 0.6406 21/32 0.6562
5/8 18 0.5568 0.6250 37/64 0.5781 19/32 0.5938 41/64 0.6406 21/32 0.6562
5/8 24 0.5739 0.6250 37/64 0.5781 19/32 0.5938 41/64 0.6406 21/32 0.6562
11/16 24 0.6364 0.6875 41/64 0.6406 21/32 0.6562 45/64 0.7031 23/32 0.7188
3/4 10 0.6273 0.7500 21/32 0.6562 11/16 0.6875 49/64 0.7656 25/32 0.7812
3/4 16 0.6733 0.7500 11/16 0.6875 45/64 0.7031 49/64 0.7656 25/32 0.7812
3/4 20 0.6887 0.7500 45/64 0.7031 23/32 0.7188 49/64 0.7656 25/32 0.7812
13/16 20 0.7512 0.8125 49/64 0.7656 25/32 0.7812 53/64 0.8281 27/32 0.8438
7/8 9 0.7387 0.8750 49/64 0.7656 51/64 0.7969 57/64 0.8906 29/32 0.9062
7/8 14 0.7874 0.8750 13/16 0.8125 53/64 0.8281 57/64 0.8906 29/34 0.9062
7/8 20 0.8137 0.8750 53/64 0.8281 27/32 0.8438 57/64 0.8906 29/32 0.9062
15/16 20 0.8762 0.9375 57/64 0.8906 29/32 0.9062 61/64 0.9531 31/32 0.9688
1 8 0.8466 1.000 7/8 0.8750 59/64 0.9219 1-1/64 1.0156 1-1/32 1.0313
1 12 0.8978 1.000 15/16 0.9375 61/64 0.9531 1-1/64 1.0156 1-1/32 1.0313
1 20 0.9387 1.000 61/64 0.9531 31/32 0.9688 1-1/64 1.0156 1-1/32 1.0313
1-1/16 18 0.9943 1.0625 1.000 1.000 1-1/64 1.0156 1-5/64 1.0781 1-3/32 1.0938
1-1/8 7 0.9497 1.1250 63/64 0.9844 1-1/32 1.0313 1-9/64 1.1406 1-5/32 1.1562
1-1/8 12 1.0228 1.1250 1-3/64 1.0469 1-5/64 1.0781 1-9/64 1.1406 1-5/32 1.1562
1-1/8 18 1.0568 1.1250 1-1/16 1.0625 1-5/64 1.0781 1-9/64 1.1406 1-5/32 1.1562
1-3/16 18 1.1193 1.1875 1-1/8 1.250 1-9/64 1.1406 1-13/64 1.2031 1-7/32 1.2188
1-1/4 7 1.0747 1.2500 1-7/64 1.1094 1-5/32 1.1562 1-17/64 1.2656 1-9/32 1.2812
1-1/4 12 1.1478 1.2500 1-11/64 1.1719 1-13/64 1.2031 1-17/64 1.2656 1-9/32 1.2812
1-1/4 18 1.1818 1.2500 1-3/16 1.1875 1-13/64 1.2031 1-17/64 1.2656 1-9/32 1.2812
1-5/16 18 1.2443 1.3125 1-1/4 1.2500 1-17/64 1.2656 1-21/64 1.3281 1-11/32 1.3438
1-3/8 6 1.1705 1.3750 1-7/32 1.2187 1-17/64 1.2656 1-25/64 1.3906 1-13/32 1.4062
1-3/8 12 1.2728 1.3750 1-9/64 1.2969 1-21/64 1.3281 1-25/64 1.3906 1-13/32 1.4062
1-3/8 18 1.3068 1.3750 1-5/16 1.3125 1-21/64 1.3281 1-25/64 1.3906 1-13/32 1.4062
1-7/16 18 1.3693 1.4375 1-3/8 1.3750 1-25/64 1.3906 1-29/64 1.4531 1-15/32 1.4688
1-1/2 6 1.2955 1.5000 1-11/32 1.3437 1-25/64 1.3906 1-33/64 1.5156 1-17/32 1.5312
1-1/2 12 1.3978 1.5000 1-27/64 1.4219 1-7/16 1.4375 1-33/64 1.5156 1-17/32 1.5312
1-1/2 18 1.4318 1.5000 1-7/16 1.4375 1-29/64 1.4531 1-33/64 1.5156 1-17/32 1.5312
1-9/16 18 1.4943 1.5625 1-1/2 1.5000 1-33/64 1.5156 1-37/64 1.5781 1-19/32 1.5938
1-5/8 18 1.5568 1.6250 1-9/16 1.5625 1-37/64 1.5781 1-41/64 1.6406 1-21/32 1.6562
1-11/16 18 1.6193 1.6875 1-5/8 1.6250 1-41/64 1.6406 1-45/64 1.7031 1-23/32 1.7188
1-3/4 5 1.5046 1.7500 1-9/16 1.5625 1-5/8 1.6250 1-49/64 1.7659 1-25/32 1.7812
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