This drill bit size chart lists sizes in different measurement systems, for example, fractional, metric, wire gauge, and letter sizes. Here we have made drill bit charts for different details
Fractional Drill Bit Size Chart
| Fractional Size | Decimal (in) | Metric (mm) |
|---|---|---|
| 1/64 | 0.0156 | 0.397 |
| 1/32 | 0.0313 | 0.794 |
| 3/64 | 0.0469 | 1.191 |
| 1/16 | 0.0625 | 1.588 |
| 5/64 | 0.0781 | 1.984 |
| 3/32 | 0.0938 | 2.381 |
| 7/64 | 0.1094 | 2.778 |
| 1/8 | 0.1250 | 3.175 |
| 9/64 | 0.1406 | 3.572 |
| 5/32 | 0.1563 | 3.969 |
| 11/64 | 0.1719 | 4.366 |
| 3/16 | 0.1875 | 4.763 |
| 13/64 | 0.2031 | 5.159 |
| 7/32 | 0.2188 | 5.556 |
| 15/64 | 0.2344 | 5.953 |
| 1/4 | 0.2500 | 6.350 |
| 17/64 | 0.2656 | 6.747 |
| 9/32 | 0.2813 | 7.144 |
| 19/64 | 0.2969 | 7.541 |
| 5/16 | 0.3125 | 7.938 |
| 21/64 | 0.3281 | 8.334 |
| 11/32 | 0.3438 | 8.731 |
| 23/64 | 0.3594 | 9.128 |
| 3/8 | 0.3750 | 9.525 |
| 13/32 | 0.4063 | 10.319 |
| 7/16 | 0.4375 | 11.113 |
| 15/32 | 0.4688 | 11.906 |
| 1/2 | 0.5000 | 12.700 |
| 9/16 | 0.5625 | 14.288 |
| 5/8 | 0.6250 | 15.875 |
| 11/16 | 0.6875 | 17.463 |
| 3/4 | 0.7500 | 19.050 |
| 13/16 | 0.8125 | 20.638 |
| 7/8 | 0.8750 | 22.225 |
| 15/16 | 0.9375 | 23.813 |
| 1 | 1.0000 | 25.400 |
Number Drill Bit Size Chart
| Number Drill | Decimal (in) | Metric (mm) |
|---|---|---|
| #80 | 0.0135 | 0.343 |
| #79 | 0.0145 | 0.368 |
| #78 | 0.0160 | 0.406 |
| #77 | 0.0180 | 0.457 |
| #76 | 0.0200 | 0.508 |
| #75 | 0.0210 | 0.533 |
| #74 | 0.0225 | 0.572 |
| #73 | 0.0240 | 0.610 |
| #72 | 0.0250 | 0.635 |
| #71 | 0.0260 | 0.660 |
| #70 | 0.0280 | 0.711 |
| #69 | 0.0292 | 0.742 |
| #68 | 0.0310 | 0.787 |
| #67 | 0.0320 | 0.813 |
| #66 | 0.0330 | 0.838 |
| #65 | 0.0350 | 0.889 |
| #64 | 0.0360 | 0.914 |
| #63 | 0.0370 | 0.940 |
| #62 | 0.0380 | 0.965 |
| #61 | 0.0390 | 0.991 |
| #60 | 0.0400 | 1.016 |
| #55 | 0.0520 | 1.321 |
| #50 | 0.0700 | 1.778 |
| #45 | 0.0820 | 2.083 |
| #40 | 0.0980 | 2.489 |
| #35 | 0.1100 | 2.794 |
| #30 | 0.1285 | 3.264 |
| #25 | 0.1495 | 3.797 |
| #20 | 0.1610 | 4.089 |
| #15 | 0.1800 | 4.572 |
| #10 | 0.1935 | 4.915 |
| #5 | 0.2055 | 5.220 |
| #1 | 0.2280 | 5.791 |
Letter Drill Bit Size Chart
| Letter | Decimal (in) | Metric (mm) |
|---|---|---|
| A | 0.2340 | 5.944 |
| B | 0.2380 | 6.045 |
| C | 0.2420 | 6.147 |
| D | 0.2460 | 6.248 |
| E | 0.2500 | 6.350 |
| F | 0.2570 | 6.528 |
| G | 0.2610 | 6.629 |
| H | 0.2660 | 6.756 |
| I | 0.2720 | 6.909 |
| J | 0.2770 | 7.036 |
| K | 0.2810 | 7.137 |
| L | 0.2900 | 7.366 |
| M | 0.2950 | 7.493 |
| N | 0.3020 | 7.671 |
| O | 0.3160 | 8.026 |
| P | 0.3230 | 8.204 |
| Q | 0.3320 | 8.433 |
| R | 0.3390 | 8.611 |
| S | 0.3480 | 8.839 |
| T | 0.3580 | 9.093 |
| U | 0.3680 | 9.347 |
| V | 0.3770 | 9.576 |
| W | 0.3860 | 9.804 |
| X | 0.3970 | 10.084 |
| Y | 0.4040 | 10.262 |
| Z | 0.4130 | 10.490 |
Metric Drill Bit Size Chart
| Metric (mm) | Decimal (in) |
|---|---|
| 0.5 | 0.0197 |
| 0.6 | 0.0236 |
| 0.7 | 0.0276 |
| 0.8 | 0.0315 |
| 0.9 | 0.0354 |
| 1.0 | 0.0394 |
| 1.2 | 0.0472 |
| 1.5 | 0.0591 |
| 2.0 | 0.0787 |
| 2.5 | 0.0984 |
| 3.0 | 0.1181 |
| 3.5 | 0.1378 |
| 4.0 | 0.1575 |
| 4.5 | 0.1772 |
| 5.0 | 0.1969 |
| 5.5 | 0.2165 |
| 6.0 | 0.2362 |
| 6.5 | 0.2559 |
| 7.0 | 0.2756 |
| 7.5 | 0.2953 |
| 8.0 | 0.3150 |
| 8.5 | 0.3346 |
| 9.0 | 0.3543 |
| 9.5 | 0.3740 |
| 10.0 | 0.3937 |
| 11.0 | 0.4331 |
| 12.0 | 0.4724 |
| 13.0 | 0.5118 |
| 14.0 | 0.5512 |
| 15.0 | 0.5906 |
| 16.0 | 0.6299 |
| 18.0 | 0.7087 |
| 20.0 | 0.7874 |
| 22.0 | 0.8661 |
| 25.0 | 0.9843 |
US Thread Tap Drill Sizes Chart (UNC & UNF)
This chart shows US Unified National Coarse and Unified National Fine (UNF) thread sizes with certain tap drill sizes for 75% thread engagement, which is used for engineering and manufacturing applications.
| Thread Size | Thread Series | Threads Per Inch (TPI) | Tap Drill (Inch) | Tap Drill (Decimal) | Drill Number/Letter |
|---|---|---|---|---|---|
| #0-80 | UNC | 80 | 3/64″ | 0.0469 | #56 |
| #1-64 | UNC | 64 | #53 | 0.0595 | #53 |
| #2-56 | UNC | 56 | #50 | 0.0700 | #50 |
| #3-48 | UNC | 48 | #47 | 0.0785 | #47 |
| #4-40 | UNC | 40 | #43 | 0.0890 | #43 |
| #5-40 | UNC | 40 | #38 | 0.1015 | #38 |
| #6-32 | UNC | 32 | #36 | 0.1065 | #36 |
| #8-32 | UNC | 32 | #29 | 0.1360 | #29 |
| #10-24 | UNC | 24 | #25 | 0.1495 | #25 |
| #10-32 | UNF | 32 | #21 | 0.1590 | #21 |
| 1/4″-20 | UNC | 20 | #7 | 0.2010 | #7 |
| 1/4″-28 | UNF | 28 | #3 | 0.2130 | #3 |
| 5/16″-18 | UNC | 18 | F | 0.2570 | F |
| 5/16″-24 | UNF | 24 | I | 0.2720 | I |
| 3/8″-16 | UNC | 16 | 5/16″ | 0.3125 | 5/16″ |
| 3/8″-24 | UNF | 24 | Q | 0.3320 | Q |
| 7/16″-14 | UNC | 14 | U | 0.3680 | U |
| 7/16″-20 | UNF | 20 | 25/64″ | 0.3906 | 25/64″ |
| 1/2″-13 | UNC | 13 | 27/64″ | 0.4219 | 27/64″ |
| 1/2″-20 | UNF | 20 | 29/64″ | 0.4531 | 29/64″ |
| 9/16″-12 | UNC | 12 | 31/64″ | 0.4844 | 31/64″ |
| 9/16″-18 | UNF | 18 | 33/64″ | 0.5156 | 33/64″ |
| 5/8″-11 | UNC | 11 | 17/32″ | 0.5313 | 17/32″ |
| 5/8″-18 | UNF | 18 | 37/64″ | 0.5781 | 37/64″ |
| 3/4″-10 | UNC | 10 | 21/32″ | 0.6563 | 21/32″ |
| 3/4″-16 | UNF | 16 | 11/16″ | 0.6875 | 11/16″ |
| 7/8″-9 | UNC | 9 | 49/64″ | 0.7656 | 49/64″ |
| 7/8″-14 | UNF | 14 | 13/16″ | 0.8125 | 13/16″ |
| 1″-8 | UNC | 8 | 7/8″ | 0.8750 | 7/8″ |
| 1″-12 | UNF | 12 | 59/64″ | 0.9219 | 59/64″ |
Drill Bit Sizes for CNC Machining
| Drill Type | Size | Decimal (in) | Metric (mm) | CNC Applications |
|---|---|---|---|---|
| Number | #80 | 0.0135 | 0.343 | Micro holes, PCB machining |
| Number | #70 | 0.0280 | 0.711 | Electronics, precision parts |
| Number | #60 | 0.0400 | 1.016 | Small pilot holes |
| Number | #55 | 0.0520 | 1.321 | Instrument components |
| Number | #50 | 0.0700 | 1.778 | #2-56 tap drill |
| Number | #43 | 0.0890 | 2.261 | #4-40 tap drill |
| Number | #36 | 0.1065 | 2.705 | #6-32 tap drill |
| Number | #29 | 0.1360 | 3.454 | #8-32 tap drill |
| Number | #21 | 0.1590 | 4.039 | #10-32 tap drill |
| Fractional | 1/16″ | 0.0625 | 1.588 | Small holes |
| Fractional | 3/32″ | 0.0938 | 2.381 | General drilling |
| Fractional | 1/8″ | 0.1250 | 3.175 | Clearance holes |
| Fractional | 5/32″ | 0.1563 | 3.969 | Fastener holes |
| Fractional | 3/16″ | 0.1875 | 4.763 | Pilot drilling |
| Fractional | 1/4″ | 0.2500 | 6.350 | General machining |
| Fractional | 5/16″ | 0.3125 | 7.938 | Structural components |
| Fractional | 3/8″ | 0.3750 | 9.525 | Large mounting holes |
| Fractional | 1/2″ | 0.5000 | 12.700 | Heavy-duty machining |
| Fractional | 5/8″ | 0.6250 | 15.875 | Fixture holes |
| Fractional | 3/4″ | 0.7500 | 19.050 | Large bores |
| Letter | A | 0.2340 | 5.944 | Close-fit holes |
| Letter | C | 0.2420 | 6.147 | General machining |
| Letter | F | 0.2570 | 6.528 | 5/16″-18 UNC tap drill |
| Letter | H | 0.2660 | 6.756 | Precision drilling |
| Letter | I | 0.2720 | 6.909 | 5/16″-24 UNF tap drill |
| Letter | N | 0.3020 | 7.671 | Machine components |
| Letter | Q | 0.3320 | 8.433 | 3/8″-24 UNF tap drill |
| Letter | U | 0.3680 | 9.347 | 7/16″-14 UNC tap drill |
| Letter | X | 0.3970 | 10.084 | Precision holes |
| Letter | Z | 0.4130 | 10.490 | Large pilot holes |
Drill Size Systems
Metric Drill Sizes
Metric drills are commonly used for systems that explain according to ISO 235-2016. Sizes’ value increases by 0.1mm to about 10mm, 0.5mm value enhances from 10mm to 20mm, and 1mm over 20mm.
Different CNC machining working standard metric drill sizes are used. The selected metric drill sizes are low-cost and compatible with advanced CNC machines.
For metric holes, not making sizes end in 0.05 mm is also needed. That is best for semi-standard.
Fractional Drill Sizes
Fractional drills come with 1/64″ value increases that are employed for old drawings of engineering applications in the USA and also for woodworking. They also employed for industries fractional sizes slowly replaced metric sizes in advanced manufacturing.
Accurate conversion of fractional inches to millimeters is used, rather than rounding off. A 1/4″ drill is 6.35 mm, not 6.4 mm; that is the result of thread-fitting errors.
Number Drill Sizes
Drill numbers vary from 97 to 1. That made for wire gauge size and is now used for tapping small US standard threads.
Number drills cover gaps existing between fractional values that are not enough for letter drills.
number of drill sizes reduces with high numbers. such as 1 number drill being larger compared to 80 number drills, which confuses new engineers working with US standards.
Letter Drill Sizes
Letter drills like A to Z that cover gaps of fractional sizes and are employed for medium-sized USA threads. Such number drills and letter sizes are normally employed in USA manufacturing industries.
