Tap Drill Size in The USA – A Complete Chart and Questions

Below is a comprehensive drill and tap size chart for all drills and taps, imperial and metric, up to 36.5 millimetres (1.44 in) in diameter. Such an appropriately sized drill is called a tap drill for that size of thread, because it is a correct drill to be followed by the tap.

Inch Sizes (all measurements in inches)

Tap Size and Pitch Cutting Taps Forming Taps
Drill Size Decimal Equiv. Drill Size Decimal Equiv.
0-80 3/64 .0469 54 .0550
1-72 53 .0595 51 .0670
2-56 50 .0700 5/64 .0781
2-64 50 .0700 47 .0785
3-48 47 .0785 43 .0890
3-56 46 .0810 2.30 .0905
4-40 43 .0890 38 .1015
4-48 42 .0935 2.60 .1024
5-40 38 .1015 33 .1130
5-44 37 .1040 2.90 .1142
6-32 36 .1065 1/8 .1250
6-40 33 .1130 3.25 .1280
8-32 29 .1360 25 .1495
8-36 29 .1360 24 .1520
10-24 26 .1470 11/64 .1719
10-32 21 .1590 16 .1770
12-24 16 .1770 8 .1990
12-28 15 .1800 7 .2010
1/4-20 7 .2010 1 .2280
1/4-28 3 .2130 15/64 .2340
5/16-18 F .2570 L .2900
5/16-24 I .2720 M .2950
3/8-16 5/16 .3125 S .3480
3/8-24 Q .3320 T .3580
7/16-14 U .3680 Y .4040
7/16-20 25/64 .3906 Z .4130
1/2-13 27/64 .4219 15/32 .4682
1/2-20 29/64 .4531 12.25 .4823
9/16-12 31/64 .4844 17/32 .5312
9/16-18 33/64 .5156 13.50 .5315
5/8-11 17/32 .5312 14.75 .5807
5/8-18 37/64 .5781 15.25 .6004
3/4-10 21/32 .6562 45/64 .7031
3/4-16 11/16 .6875 23/32 .7188
7/8-9 49/64 .7656 .* .*
7/8-14 13/16 .8125 .* .*
1-8 7/8 .8750 .* .*
1-12 59/64 .9219 .* .*
1-1/8 – 7 63/64 .9844 .* .*
1-1/8 – 12 1 3/64 1.0469 .* .*
1-1/4 – 7 1 7/64 1.1094 .* .*
1-1/4 – 12 1 11/64 1.1719 .* .*
1-3/8 – 6 1 7/32 1.2188 .* .*
1-3/8 – 12 1 19/64 1.2969 .* .*
1-1/2 – 6 1 11/32 1.3438 .* .*
1-1/2 – 12 1 27/64 1.4219 .* .*

Metric Sizes (measurements in millimeters and inches)

Tap Size and Pitch mm Cutting Taps Forming Taps
Drill Size mm Decimal Equiv. in Drill Size mm/in Decimal Equiv. in
M1.6 x 0.35 1.25 .0492 1.45 .0571
M1.8 x 0.35 1.45 .0571 1.65 .0650
M2 x 0.40 1.60 .0630 1.80 .0709
M2.2 x 0.45 1.75 .0689 2.00 .0787
M2.5 x 0.45 2.05 .0807 2.30 .0906
M3 x 0.50 2.50 .0984 7/64 .1094
M3.5 x 0.60 2.90 .1142 3.20 .1260
M4 x 0.70 3.30 .1299 3.70 .1476
M4.5 x 0.75 3.70 .1476 4.10 .1614
M5 x 0.80 4.20 .1654 14 .1820
M6 x 1.00 5.00 .1969 7/32 .2188
M7 x 1.00 6.00 .2362 F .2570
M8 x 1.25 6.70 .2638 7.40 .2913
M8 x 1.00 7.00 .2756 19/64 .2969
M10 x 1.50 8.50 .3346 U .3680
M10 x 1.25 8.70 .3425 9.40 .3701
M12 x 1.75 10.20 .4016 11.20 .4409
M12 x 1.25 10.80 .4252 11.50 .4528
M14 x 2.00 12.00 .4724 33/64 .5156
M16 x 2.00 14.00 .5512 19/32 .5938
M16 x 1.50 14.50 .5709 15.25 .6004
M18 x 2.50 15.50 .6102 39/64 .6094
M18 x 1.50 16.50 .6496 17.25 .6791
M20 x 2.50 17.50 .6890 * .*
M20 x 1.50 18.50 .7283 * .*
M22 x 2.50 19.50 .7677 * .*
M22 x 1.50 20.50 .8071 * .*
M24 x 3.00 21.00 .8268 * .*
M24 x 2.00 22.00 .8661 * .*
M27 x 3.00 24.00 .9449 * .*
M27 x 2.00 25.00 .9843 * .*
M30 x 3.50 26.50 1.0433 * .*
M30 x 2.00 28.00 1.1024 * .*
M33 x 3.50 29.50 1.1614 * .*
M33 x 2.00 31.00 1.2205 * .*
M36 x 4.00 32.00 1.2598 * .*
M36 x 3.00 33.00 1.2992 * .*
M39 x 4.00 35.00 1.3780 * .*
M39 x 3.00 36.00 1.4173 * .*

Pipe Tap Sizes (measurements in millimeters and inches)

Nominal                       NPT & NPTF
Pipe Tap Size Without Reamer With Reamer NPSM NPSC NPSF
1/16-27 C .242 A .234 .250 D .246
1/8-27 Q .332 21/64 T .358 Q .332 R .339
1/4-18 7/16 27/64 15/32 7/16 7/16
3/8-18 9/16 9/16 .603 (special) 37/64 37/64
1/2-14 45/64 11/16 19 mm 18 mm 18 mm
3/4-14 29/32 57/64 61/64 59/64 59/64
1 – 11-1/2 1 9/64 1 1/8 1 13/64 1 5/32 1 5/32
1-1/4 –11-1/2 1 31/64 1 15/32 1 35/64 1 1/2
1-1/2 –11-1/2 1 23/32 1 45/64 1 25/32 1 47/64
2 – 11-1/2 2 3/16 2 11/64 2 1/4 2 13/64

Important FAQ of Tap Drill

Q: What is tap drill?
Ans:  drill for drilling a hole of exact diameter for tapping.

Q: What is a tap drill bit used for?

Ans: List of Drill Bit and Tap Sizes – Drill Size Chart and Tap Size Chart | CNCLATHING. Drilling is a process of producing a hole while tapping is a technique used to cut a thread inside a hole, so the drill bit and tapping tool are often used in sequential to fabricate CNC parts with thread holes.

Q: Can you tap with a hand drill?

Ans: You can preload the spring center with some pressure and then turn the tap handle by hand. The drill press is just keeping things in alignment. Continue tapping until you have a number of threads and then the drill press has done its job and you can go freehand.

Q: What are the 3 types of taps?

Ans:

  • Spiral Point Taps (Bull Nose Taps) …
  • Spiral Flute Taps (Gun Taps) …
  • Roll Form Taps (Thread Forming Taps)

Q: How do I choose a drill bit for a tap?

Ans: A good tap drill is 90% (± 2 pp) of major diameter for fine threads. For metric V threads, the concept of major minus pitch (i.e., the major or widest diameter of the intended screw in millimeters minus the pitch of the threads of that screw in millimeters per thread) yields a good tap drill diameter.

Q: How do I know what tap to use?

Ans: Determine the Threads Per Inch. A die set is used to cut threads onto a cylinder (bolt). To use a tap or a die, first determine the number of threads per inch (TPI) of the part to be fixed. A gauge system that has a number of different pins can be used to calculate the TPI of a bolt or nut.

Q: How do I choose a tap size?

Ans: To determine the proper drill size for 75% thread on a special pitch tap use the following formula: Drill Size = Major Diameter – (. 975 divided by the number of threads per inch). For example, with a 1/4-32 tap

Q: What is the difference between threading and tapping?

Ans: A tap is used to cut or form the female portion of the mating pair (e.g. a nut). A die is used to cut or form the male portion of the mating pair (e.g. a bolt). The process of cutting or forming threads using a tap is called tapping, whereas the process using a die is called threading.

Q: Can you tap a hole using a drill?

Ans: A drill press can help keep the tap aligned much more accurately than you can do freehand. There are two functions that the drill press can serve to help you tap a hole. The first thing is to keep the tap aligned with the hole that you’re tapping.

Q: Can I use a drill to tap a hole?

Ans: Trapping a hole is the process by which you give them threads so that they can accommodate a screw, and doing it to a lot of holes quickly can be a major pain. Fortunately, you can actually do it with a cordless power drill much more quickly and easily than manually.

Q: Can you put a tap in a drill press?

Ans: Tapping by hand on a drill press is usually accomplished by drilling the part with a tap drill, then placing a 60-degree straight shank center, or spring center (Figure 1), in the drill chuck.

Q: What are the three taps in a standard tap set?

Ans: Hand taps come in three basic configurations -Taper, Plug and Bottoming.

Q: Does it matter which side you tap a hole from?

Ans: When a tap is used it only cuts in one direction, typically clockwise for standard threads. As the tap is spun it will progressively work its way deeper into the hole as it cuts new threads. If the tap is spun counter-clockwise it will back itself out of the hole, similarly to backing out a threaded fastener.

Q: What drill bit do I use to tap a 5/16 hole?

Ans: You should get around . 2583, which you then round up to the nearest drill bit size. In this case, the most relative drill bit size corresponding to the 5/16″-18 tap is 17/64, which corresponds to an F drill bit.

Q: What does it mean to tap a screw?

Ans: What is tapping? Tapping is the process of cutting a matching set of threads into a piece of metal, plastic, acrylic, or wood. The process of tapping uses two separate tools: the tap which cuts the threads on the inner diameter of the hole, and the die which cuts the threads on the outer diameter of the bolt or screw.

Q: Are all tap fittings the same size?

Ans: The most common length of flexible tap connector is 300mm although some variations come in 150mm, 500mm and 1000mm. … They come in pairs and have thread sizes of either 10mm or 12mm with each tap connector in the pair having slightly different lengths of solid tail to make access to tightening easier.

Q: What does 6H mean on a tap?

Ans: It was answered on 4 May. The metric thread 8mm of ISO standard is referred to as m8 and the tolerance of threaded hole is referred to as 6H

Q: Is taping faster than threading?

Ans: The greatest advantage of tapping is speed. High-speed tapping centers set up with a rigid tap can thread holes in a fraction of the time it would take to thread mill the same holes. Additionally, tapping can thread deeper holes in harder materials such as steel.

Q: What is the difference between a self tapping screw and a normal screw?

Ans: Self-tapping screws are different to traditional screws as they tap their own threads when screwed into either plastic, wood or metal. Self-tapping screws are usual split into two variants thread forming and thread tapping.

Q: What is the process of tapping?

Ans: Tapping is the process of cutting a thread inside a hole so that a cap screw or bolt can be threaded into the hole. Also, it is used to make thread on nuts. Tapping can be done on the lathe by power feed or by hand.

Q: What is CNC tapping?

Ans: One of the most common methods of tapping in use today on CNC machines is ‘rigid tapping’ or ‘synchronous feed tapping. ‘ A rigid tapping cycle synchronizes the machine spindle rotation and feed to match a specific thread pitch.

Q: Is 5mm the same as 3 16?

Ans: 5mm = just over 3/16 inch. 6mm = almost 1/4 inch. 7mm = almost 9/32 inch (= a bit over 1/4 inch) 8mm = 5/16 inch.

Q: How do you determine tap drill size?

Ans: As a rule of thumb, for Metric threads, the tapping drill can be calculated by subtracting the pitch from the diameter of the thread. eg for an M5x0. 75 thread the tapping drill is 5-0.75mm = 4.25mm. For Imperial (inch) threads the tapping drill size is calculated in the same way, diameter minus pitch.

Q: What drill bit do you use for a tap?

Ans: The best overall size drill bit for 1/4″ 20 tap is a #7 drill bit, the measurement being 13/64”. The concept of tapping threads is relatively simple, but in practice, it can get complicated. If the hole is too small, the tapping will extend too far into the center making it difficult to screw the bolt into the hole.

Q: Why is the size of the tap drill important?

Ans: Drill might be a better choice. The slightly larger drill diameter still provides a 73 per cent of thread value, which is more than acceptable. But that two per cent reduction in thread percentage will reduce torque on the cutting tool and increase tap tool life.

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