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Free Printable Drill Bit Size Charts [Taps, Screws] PDF

    Whether you’re a professional contractor or a weekend DIYer, having the right drill bit size is crucial for any project requiring holes to be drilled. Drill bits come in a range of diameters, with each size suited for specific applications and materials. To help choose the optimal bit, drill bit size charts provide a valuable reference. In this article, we’ll explore drill bit sizes, from small-scale bits used by jewelers to large-diameter auger bits used in construction.

    A drill bit size chart is included, offering a visual guide to the extensive range of bit sizes readily available. With this chart, you’ll be able to conveniently match project needs to the appropriate drill bit diameter. The result is efficiently drilled holes cut to precise specifications. So next time you’re debating which bit to use, consult the chart to pick the proper size and achieve drilling success.

    What Is A Drill Bit Size Chart?

    Drill Bit Size Chart
    Drill Bit Size Chart

    A drill bit size chart is a table or graphic that displays the range of available drill bit diameters, along with the intended uses and suitable materials for each drill bit size. The chart typically includes bit sizes starting from very small diameters like 0.2mm that are used for drilling tiny holes in electronics or jewelry, up to large diameter bits exceeding 50mm for applications like drilling holes in wood posts or concrete.

    The increasing drill bit sizes are organized sequentially or visually for convenient reference. With the drill bit size chart’s clear presentation of the drill bit options, users can easily determine the ideal bit diameter needed for the material and hole size of a given drilling task.

    Printable Drill Bit Size Chart

    Drill bits come in a wide variety of sizes and are measured either in millimeters or inches depending on where you live. A drill bit size chart is an invaluable tool for any workshop to quickly look up the right size bit for the job. The chart displays a comprehensive list of metric and imperial drill bit sizes along with the equivalent sizes in the other measurement system.

    For example, a 1/4 inch drill bit is closest in size to a 6.5mm drill bit. The chart has drill bit sizes ranging from tiny 1mm bits all the way up to massive 1 inch (25mm) bits. The most common sizes used for general DIY and construction work tend to range from 3mm to 16mm.

    Having a drill bit size chart pdf printed out and pinned up in your workshop saves you time and removes guesswork when selecting the proper bit. The pdf chart allows you to zoom in and clearly read the size markings without any blurriness. You can find printable drill bit size chart pdfs online for free by searching for “drill bit size chart pdf” and downloading the specific chart you need for the bit scale you use.

    The Importance of Using the Correct Drill Bit Size

    Drilling is a common task in a wide variety of projects, from simple home DIY projects to complex industrial operations. Regardless of the scope of the work, using the correct drill bit size is essential for various reasons. Here are the main points highlighting the importance of using the right drill bit size:

    1. Precision and Accuracy: To achieve the exact hole diameter that a project demands, the correct drill bit size is paramount. Whether you’re hanging a photo, installing a shelf, or working on intricate machinery, the precision and accuracy of the hole can affect the final result and the stability of the installation.
    2. Reduced Risk of Damage: Using a drill bit that’s too large can cause splintering or cracking, especially in fragile materials like ceramics or certain woods. On the other hand, starting with a drill bit that’s too small and then forcing it can cause strain on the material and the tool.
    3. Efficiency: Using the right-sized bit helps you drill holes more efficiently. If you use a bit that’s too small, you might need to enlarge the hole with a bigger bit later on, requiring additional time and effort. Conversely, a bit that’s too large can remove more material than necessary, wasting energy and resources.
    4. Protecting the Tool: Using the wrong drill bit size can strain the drilling tool. A bit that’s too large for a certain material can make the drill work harder, which might cause it to overheat or wear out faster. Similarly, using a bit that’s too small and then applying excessive force can damage the bit or the drill’s motor.
    5. Safety: Using the correct drill bit size reduces the chance of the bit slipping or the material breaking, both of which can cause accidents. A slipping drill can lead to injuries, while shattered materials can produce sharp fragments.
    6. Longevity of Drill Bits: Correctly matching the bit size with the intended hole ensures the bit wears uniformly. Using an inappropriate size can result in uneven wear or premature dulling of the bit.
    7. Clean Finish: For many projects, especially in carpentry or crafts, the finish of the drilled hole matters. A hole that’s smooth and free from splinters or chips looks more professional and may not require as much post-drilling work, such as sanding.
    8. Secured Fastening: When installing screws, bolts, or anchors, the hole’s size can influence the strength of the fastening. A hole that’s too large may not hold the screw securely, while one that’s too small might not allow the screw to enter at all.
    9. Cost Efficiency: Repeatedly damaging materials or breaking drill bits because of size mismatches can add unnecessary costs to a project. Using the right size the first time minimizes waste and reduces expenses.
    10. Confidence in Results: Knowing that you’re using the right tools for the job brings peace of mind. You can trust in the quality of your work when you’re sure about your equipment.

    Types of Drill Bits

    Let’s delve into the different types of drill bits and their respective uses:

    Twist Drill Bits

    Twist drill bits are the most common type of drill bits and are recognizable by their cylindrical shaft and pointed tip. Made from high-speed steel, cobalt, or carbide, these bits are designed for general drilling purposes in metal, plastic, wood, and other materials. Their helical design helps in removing chips from the hole as it’s being drilled. Twist drill bits come in various sizes, making them versatile for numerous applications. They’re also relatively easy to sharpen, ensuring a longer lifespan with proper maintenance. However, for specialized tasks or materials, there are more appropriate bit types to consider.

    Masonry Bits

    Masonry bits are specifically designed for drilling into hard materials like brick, concrete, stone, and tiles. They feature a tough, wide, flat tip made of carbide to withstand the abrasive nature of masonry work. The body of a masonry bit may be twisted like a regular drill bit or designed with flutes. When used with a hammer drill, the bit not only rotates but also hammers into the material, making it easier to bore through tough masonry surfaces. Proper cooling and lubrication, typically with water, can extend their lifespan, especially when drilling into particularly hard materials.

    Spade Bits

    Spade bits, also known as paddle bits, are designed to drill large holes in wood. They feature a flat, spade-shaped blade with a pointed tip at the center, which helps in positioning the bit. The blade edges cut the circumference of the hole while the broad paddle-like structure removes the material. Spade bits are excellent for tasks like running conduit or piping through wooden studs. They tend to create rougher holes, making them unsuitable for fine woodworking but perfect for tasks where the finish isn’t a primary concern.

    Forstner Bits

    Forstner bits are used for drilling precise, flat-bottomed holes in wood. They have a unique appearance with a cylindrical cutter around the perimeter and a pointed center spike for positioning. These bits are ideal for applications like drilling holes for European-style cabinet hinges or when the hole’s side will be exposed in joinery applications. They produce very clean holes with smooth walls and can even be used to drill at an angle or to overlap existing holes.

    Step Drill Bits

    Step drill bits, often made from high-speed steel, are cone-shaped with a series of increasing diameters along their length. They are primarily used for drilling holes in thin materials like sheet metal. The design allows the user to enlarge a hole by drilling deeper with the same bit. Each step on the bit corresponds to a specific diameter, making it versatile and convenient for tasks requiring various hole sizes.

    Countersink Bits

    Countersink bits are designed to create a conical opening at the top of a hole, allowing screw heads to sit flush with or below the surface of the material. They can be standalone bits or sometimes combined with a twist bit for drilling pilot holes. They are crucial in woodworking and finish carpentry, where the appearance of the final product is paramount. By allowing screws to sit flush, they help in achieving a neat and professional look.

    Auger Drill Bits

    Auger bits are specialized wood-drilling bits with a long, spiraled design. They have a threaded tip that pulls the bit into the wood, making the drilling process more efficient. The deep spirals help in quickly removing chips from the hole. Auger bits are commonly used in construction, carpentry, and timber framing. Their design allows for deep drilling with minimal effort, and they produce relatively clean holes.

    Hole Saw Bits

    Hole saw bits aren’t truly “bits” in the traditional sense but are cylindrical saws used to cut large diameter holes in a variety of materials, from wood and plastic to metal and masonry. The central bit stabilizes the cut, while the cylindrical saw blade cuts the perimeter of the hole. They’re often used in plumbing, electrical installations, and any application where large-diameter holes are needed. It’s essential to use the appropriate type and ensure steady pressure for a clean cut.

    Standard Drill Bit Size Chart

    Drill bits come in a range of sizes to accommodate different drilling needs. Here’s a brief overview of the standard drill bit size charts for the various measurement systems:

    Fractional Inches

    Fractional inch drill bits are measured in simple fractions of an inch and are typically used in the U.S. Some common sizes you might encounter include:

    • 1/16 inch
    • 1/8 inch
    • 3/16 inch
    • 1/4 inch
    • … and so on, up to 1 inch and beyond.

    They usually increase in increments of 1/16 or 1/32 of an inch. These are common for many household and woodworking tasks.

    Letter Sizes

    Letter size drill bits are designated by letters of the alphabet, from A to Z. This system provides a more nuanced range of sizes that fall between the fractional inches. The sizes increase from ‘A’ (the smallest, at approximately 0.234 inches or 5.944mm) to ‘Z’ (the largest, at about 0.413 inches or 10.490mm). Letter sizes are often used in specialized tasks and industries where the typical fractional inch sizes aren’t specific enough.

    Numbered Gauge Sizes

    The numbered gauge system (often referred to as wire gauge) provides an even more detailed sizing scale, especially for smaller drill bit sizes. The sizes run from #80 (the smallest, at about 0.0135 inches or 0.343mm) to #1 (the largest in this system, at around 0.228 inches or 5.791mm). These drill bits are often used in intricate tasks such as electronics, fine woodworking, or detailed metalwork.

    Metric Sizes

    As the name suggests, metric-sized drill bits are measured in millimeters and are widely used internationally. These sizes can range from very small diameters, like 0.1mm, up to 25mm and even larger. The advantage of the metric system is its straightforward nature, as it’s based on units of ten. Common sizes might include:

    • 1mm
    • 2mm
    • 3.5mm
    • 10mm
    • … and so on.

    Depending on the application, metric drill bits might increase in increments of 0.1mm, 0.5mm, or 1mm.

    Conversion Between Measurement Systems

    In the realm of drilling, it’s often necessary to convert between different measurement systems to ensure accuracy and compatibility. Given the global nature of manufacturing and trade, understanding these conversions can be crucial. Let’s dive into how one can convert between common drill bit measurement systems.

    1. Fractional Inches to Metric

    Converting from fractional inches to metric (millimeters) generally involves multiplying the fractional inch measurement by 25.4 (since there are 25.4 millimeters in an inch).


    1. Convert the fraction to a decimal. For instance, 3/8 would be 0.375.
    2. Multiply the decimal by 25.4 to get the metric equivalent.

    Example: For a 3/8 inch bit: 0.375 inch x 25.4 = 9.525 mm

    2. Metric to Fractional Inches

    To convert from metric to fractional inches, you would reverse the process described above.


    1. Divide the metric measurement by 25.4 to get the decimal inch value.
    2. Convert the decimal inch value to its closest fractional representation for simplicity.

    Example: For a 10 mm bit: 10 mm ÷ 25.4 = 0.3937 inches, which is slightly more than 3/8 inches but less than 1/2 inches.

    3. Letter and Numbered Sizes to Metric and Fractional Inches

    Letter (A to Z) and numbered (#1 to #80) drill sizes are unique systems primarily used in the U.S. The conversion from these sizes to metric or fractional inches is not as straightforward as simple multiplication or division. Instead, one typically refers to standardized charts for accurate conversions.


    1. Locate the letter or numbered size on a drill bit conversion chart.
    2. Find the corresponding metric and fractional inch values in the adjacent columns.

    Example: If you have a ‘Q’ sized drill bit, you’d refer to a conversion chart. A common measurement for a ‘Q’ sized drill bit is 0.3320 inches or roughly 8.433 mm.

    How Do You Read A Drill Bit Chart?

    Reading a drill bit chart might initially seem complex due to the various measurement systems and detailed size specifications. However, by breaking it down step by step, it becomes a straightforward process. Here’s a guide on how to read a drill bit chart:

    Step 1: Identify the Type of Measurement

    Before diving into the chart, identify the measurement system in use. Drill bit charts can be in fractional inches, letter sizes, numbered gauge sizes, or metric sizes. The type of measurement will be usually labeled at the top or side of the chart. By determining the measurement system, you set a clear context for interpreting the rest of the information.

    Step 2: Understand the Columns and Rows

    Examine the structure of the chart. Most drill bit charts are organized in columns and rows, like a table. Typically, one column will list the drill bit size, be it in numbers, letters, or fractions. Adjacent columns might provide equivalent measurements in different systems or additional data like decimal inches or millimeters.

    Step 3: Locate the Desired Size

    Once you’re familiar with the layout, find the size you’re interested in. If you have a specific measurement in mind, look through the appropriate column until you find it. If you’re trying to match a drill bit without knowing its size, you might need to measure the bit first using calipers or a ruler, then compare it to the chart.

    Step 4: Cross-reference with Other Measurements

    This step is especially useful if you’re trying to understand the size in a different measurement system. Once you’ve located the desired size in one measurement system, follow the row across to see its equivalent size in other systems. For instance, if you’ve identified a drill bit size in fractional inches and want to know its metric equivalent, find the corresponding entry in the metric column on the same row.

    Step 5: Note any Additional Information

    Some drill bit charts provide supplementary details like the recommended drilling speeds for different materials or the optimal RPM (revolutions per minute) for each bit size. After you’ve identified the drill bit size and its equivalents, it’s a good idea to check if the chart provides any of this additional guidance, as it can help you achieve the best drilling results.

    Step 6: Double-check for Accuracy

    Always double-check to ensure you’ve read the chart correctly, especially if selecting a drill bit for a critical application. Misreading the chart or mistaking one measurement system for another can lead to errors in your work.

    Step 7: Store or Bookmark the Chart for Future Reference

    After you’ve successfully read and interpreted the drill bit chart, keep it handy for future reference. Whether it’s a physical chart in your workshop or a digital version on your device, having easy access will save time and ensure consistent, accurate work in the future.


    With such an extensive range of drill bits available, selecting the right size and style for your project can seem daunting. Fortunately, the drill bit size chart included with this article offers a handy visual reference to help match your needs to the optimal bit. The chart displays common bit types, useful diameters, and recommended applications. Whether you need a micro-scale twist bit for electronics, a masonry SDS bit for concrete drilling, or a paddle bit for boring large holes in wood, the chart has got you covered.

    With this free downloadable PDF chart, you’ll be able to visualize the drill bit sizes and quickly find the perfect match. Keep the chart readily available in your workspace or saved on your phone for anytime you’re getting ready to drill. Choosing the right drill bit diameter doesn’t have to be frustrating; armed with this chart, your next DIY or construction project can get off to a hole-y good start!


    Why are there different measurement systems for drill bits?

    Different measurement systems have evolved based on regional preferences, industry standards, and specific application needs. For example, the U.S. traditionally uses fractional inches, while much of the rest of the world uses the metric system. Letter and numbered systems offer more precise sizes for specialized tasks.

    How do I convert from metric sizes to fractional inches?

    To convert from metric to fractional inches, divide the metric measurement by 25.4 to get the decimal inch value. Then, you can convert this decimal value to the nearest common fractional inch equivalent. For exact conversions, refer to a drill bit size chart.

    Are drill bit size charts standardized across brands and manufacturers?

    While the actual dimensions of drill bit sizes (like 1/4 inch or 5 mm) are standardized, different manufacturers might have variations in recommendations for usage, material compatibility, or drilling speeds. Always refer to the specific chart or documentation provided by the manufacturer of the drill bits you are using.

    How accurate are drill bit size charts?

    Professionally produced drill bit size charts are designed to be very accurate. However, for critical applications, it’s always a good idea to double-check with manufacturer-specific documentation or use precision measuring tools to confirm the size of an unmarked bit.

    I found an old drill bit without markings. How can I determine its size?

    You can measure the diameter of the drill bit using calipers or a precision ruler. Once you have the measurement, you can refer to a drill bit size chart to identify its likely size in the various measurement systems.

    Can I use a drill bit size chart for all materials?

    While the size of the drill bit remains consistent regardless of the material, some charts provide additional information about suitable materials or recommended drilling speeds for each bit size. It’s important to choose the right type of drill bit for the material you’re working with.

    Can drill bits wear down, affecting their size?

    Yes, with repeated use, especially on hard materials, drill bits can wear down, slightly reducing their diameter. If precise sizing is crucial for your project, regularly check and replace worn drill bits.

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    Betina Jessen

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