The Ultimate Screw Size Guide & Chart (Wood, Metal, Drywall & More)
Ever driven a screw only to have it poke out the other side or worse, fail to hold anything at all? That’s what happens when you use the wrong screw size. Whether you're putting up a shelf, mounting hardware, or assembling furniture, choosing the right screw keeps your hardware sturdy and helps it to last long.
Screws may look simple, but they're precision-engineered for specific tasks. The right size affects not only how securely materials hold together, but also how easy installation is, how well the finish holds up over time, and whether the material stays undamaged.
This guide covers everything you need to know:
- What screw size numbers actually mean (imperial vs. metric)?
- How to choose the right diameter and length for your material?
- When to use #6 vs #8 vs #10 screws?
- Which screw to use with which material?
We’ll also walk you through material-specific recommendations for wood, metal, drywall, and more, so you never have to second-guess the hardware again.
Let’s start with the universal reference tool: the screw size chart.
Screw Size Chart (Imperial + Metric)
Finding the right screw size isn’t just about guessing what looks right. It requires matching the correct gauge, diameter, and length to your material and application. This is where a screw size chart becomes an essential reference tool.
Here’s a more complete view of commonly used screw sizes:
Screw Size Reference Table
Screw Size | Inch Decimal | Nearest Fraction | Metric Equivalent |
#0 | 0.060 in. | 1/16" | 1.52 mm |
#1 | 0.073 in. | 5/64" | 1.85 mm |
#2 | 0.086 in. | 3/32" | 2.18 mm |
#3 | 0.099 in. | 7/64" | 2.51 mm |
#4 | 0.112 in. | 7/64" | 2.84 mm |
#5 | 0.125 in. | 1/8" | 3.18 mm |
#6 | 0.138 in. | 9/64" | 3.51 mm |
#8 | 0.164 in. | 5/32" | 4.17 mm |
#10 | 0.190 in. | 3/16" | 4.83 mm |
#12 | 0.216 in. | 7/32" | 5.49 mm |
#14 | 0.250 in. | 1/4" | 6.35 mm |
Common Imperial to Metric Lengths
If you're more familiar with inches but come across measurements in millimeters (or vice versa), this table helps you convert between the two. It's especially useful if you're using tools or hardware made outside the U.S.
US (Inches) | Metric (mm) | US (Inches) | Metric (mm) |
1/16" | 1.59 mm | 1-3/8" | 34.93 mm |
1/8" | 3.18 mm | 1-1/2" | 38.10 mm |
3/16" | 4.76 mm | 1-5/8" | 41.28 mm |
1/4" | 6.35 mm | 1-3/4" | 44.45 mm |
5/16" | 7.94 mm | 1-7/8" | 47.63 mm |
3/8" | 9.53 mm | 2" | 50.80 mm |
7/16" | 11.11 mm | 2-1/4" | 57.15 mm |
1/2" | 12.70 mm | 2-1/2" | 63.50 mm |
9/16" | 14.29 mm | 2-3/4" | 69.85 mm |
5/8" | 15.88 mm | 3" | 76.20 mm |
11/16" | 17.46 mm | 3-1/4" | 82.55 mm |
3/4" | 19.05 mm | 3-1/2" | 88.90 mm |
7/8" | 22.23 mm | 3-3/4" | 95.25 mm |
1" | 25.40 mm | 4" | 101.60 mm |
1-1/4" | 31.75 mm |
Tips for Using This Chart
- Gauge refers to the thickness of the screw shaft; the higher the number, the thicker the screw.
- Screw length is usually measured from where the screw meets the material to the tip. For flat heads, this includes the head; for rounded heads, it does not.
- Use conversion charts to match inch sizes to millimeters when working across U.S. and international standards.
Whether you're upgrading cabinet hardware or framing out a structure, using a chart like this saves time, materials, and guesswork.
How to Read Screw Sizes
If you've ever looked at a box labeled "#8 x 1-1/2" screw" and had no idea what that meant, you're not alone. Screw sizes can be confusing at first glance, but once you understand how to read them, it becomes second nature.
What Do the Numbers Actually Mean?
- The first number (like #6, #8, or #10) refers to the screw’s diameter or thickness.
- The second part (like 1-1/2") is the length of the screw, from the point to where the screw meets the surface of the material.
Understanding Diameter
The screw’s diameter tells you how wide the shaft is. A higher gauge number means a thicker screw. For example:
- A #6 screw is 0.138 inches wide
- A #10 screw is 0.190 inches wide
This might not sound like a big difference, but when you're working with different materials (like soft wood vs. metal), it matters a lot.
Identifying parts of a screw matter because:
- Head size: Determines what kind of driver fits the screw.
- Diameter: The shaft width, which impacts strength and fit.
- Length: Impacts how deep the screw can anchor into your material.
- Thread pitch: The distance between threads is important for grip and compatibility.
Screw Lengths Explained
When it comes to screws, length matters just as much as thickness. Choosing the right length ensures the fastener goes deep enough to hold, but not so deep that it splits the material or pokes through the other side.
How Is Screw Length Measured?
Different types of screws are measured in different ways. Take a look at how the type of screw matters when you’re measuring tit’s length.
- Flat head screws (countersunk): Length is measured from the top of the head to the tip.
- Round, pan, hex head screws: Measured from under the head to the tip.
This distinction is crucial, especially when working on cabinets, drywall, or any visible surface.
Mistakes to Avoid
- Using too short a screw: weak grip, likely to pull out.
- Using too long a screw: may damage the surface or material behind it.
- Ignoring the material type: hardwoods need longer screws than softwoods for the same hold strength.
Picking the right screw length keeps your projects secure, clean, and professional-looking. Next, we’ll explore how to choose screws based on material because drywall, wood, and metal all play by different rules.
Choosing the Right Screw Size by Material
Not all materials are created equal, and neither are the screws that go into them. Using the right screw type and size for your material prevents cracks, stripping, or weak joins.
Screw Recommendations by Material
Material | Recommended Screw Type | Size Range (Common) | Notes |
Wood | Wood screws with coarse threads | #6 to #10, 1"–3" | Longer screws for load-bearing. Pre-drill in hardwood. |
Drywall | Drywall screws (sharp or self-drilling) | #6 to #8, 1-1/4"–2" | Use anchors for heavier loads. Don’t rely on drywall alone. |
Metal | Self-tapping or machine screws | #8 to #14, varies | Fine threads for thin sheet metal. Pre-drill pilot holes. |
Concrete/Brick | Masonry screws with anchors | 1-1/4"–3" | Use anchors and hammer drills. Expansion anchors are preferred. |
Plastic/Composite | Coarse-thread wood or sheet metal screws | #6 to #10 | Go slow to avoid cracking. Pre-drill recommended. |
Common Mistakes to Avoid
- Using wood screws in metal: won’t bite properly; likely to slip or strip.
- Skipping anchors in drywall: screws will loosen over time underweight.
- Overdriving screws in plastic: leads to fractures or stripped holes.
- Choosing screws too short for softwood or MDF: causes wobbly joints.
Pro Tip: When in doubt, check both thread style and material compatibility. The screw should be matched not just by size, but by function: grip strength, thread pitch, and head shape all play a role.
Next, we’ll look at the most commonly used screw sizes, and where they show up in everyday hardware tasks.
Common Screw Sizes and Their Uses
Some screw sizes show up again and again in home projects, repairs, and even electronics. This section breaks down popular screw sizes, what they're used for, and why they work well in those situations.
Popular Screw Sizes and Their Typical Applications
Screw Size | Common Uses | Notes |
#6 x 1" | Light-duty wood joinery, trim, hinges | Ideal for indoor applications where less force is required |
#8 x 1-1/4" | Cabinets, furniture assembly | A go-to for interior wood connections |
#10 x 1-1/2" | Drywall into studs, heavy frames | Offers strong hold without splitting studs |
#12 x 2" | Metal brackets, structural hardware | Often used where added grip strength is needed |
#14 x 2-1/2" | License plates, decking clips | Common in outdoor use; pair with corrosion-resistant coatings |
M6 x 16mm | Automotive parts, light machinery | Metric size, used in imported or precision builds |
M4 x 10mm | Electronics, appliance panels | Very small, precise threading |
Additional Tip: Keep These in Your Toolbox
If you’re building a starter kit, include a multi-pack with the following:
- #6 x 1"
- #8 x 1-1/4"
- #10 x 1-1/2"
- Wall anchors for #6 and #8
This small set will cover most basic household repairs and furniture builds.
Screw Size FAQs
What size is a #10 screw?
A #10 screw has a diameter of approximately 0.190 inches (4.83 mm). It’s commonly used for medium-duty fastening, like securing shelves or attaching heavy brackets to studs.
Is #8 or #10 bigger?
The higher the number, the thicker the screw. So yes, a #10 screw is thicker (and usually stronger) than a #8 screw.
How do I measure a screw?
Measure length from:
- The top of the head to the tip if the screw is flat or countersunk.
- Just under the head to the tip for round, pan, or hex heads.
Use a caliper or ruler to measure the diameter across the threads.
Can I use metal screws in wood?
Technically, yes, but it’s not recommended. Metal screws usually have fine threads, which don’t grip wood fibers well. For a strong, lasting hold, use wood screws with coarser threads.
What’s the most common screw size?
In household use, #8 x 1-1/4" is extremely common. It’s great for furniture, light framing, and cabinets
Do screw threads matter?
Yes. Coarse threads are better for soft materials like wood and plastic. Fine threads are ideal for metal or dense hardwoods where grip must be tighter and cleaner.
Final Words!
Getting the right screw is easy when you know the material, measure carefully, and use reference tools when in doubt. This guide gave you the foundation to make confident decisions, whether you're installing hardware, mounting a frame, or tackling a weekend project.
Final Screw-Choosing Checklist:
- Know the material: wood, drywall, metal, etc.
- Use the correct diameter and thread type
- Choose the right length based on thickness and depth
- Always measure screw length correctly based on head type
- Keep a size chart handy
When in doubt, don’t guess, check. And if you’re building a toolkit, stock a mix of #6, #8, and #10 screws in 1"–2" lengths with a few anchors. It’s a small investment that prevents big headaches.
Explore more screw guides, sizing charts, and installation tips at our knowledge center or visit the DK Hardware Supply Store for the hardware that gets the job done right.