What Size Thread to Use When Sewing a Button

Everyone · Explainer · Updated October 1, 2026 · LearnLife Editorial

What Size Thread Should I Use to Sew a Button?

Choosing the correct thread size for sewing a button depends on the weight of the fabric and the button's dimensions. Thread sizes are numbered, with smaller numbers indicating thicker threads. For most everyday garments like dress shirts, blouses, or light jackets, a medium-weight thread sized between 40 and 50 is optimal. This size is thick enough to hold the button firmly but thin enough to avoid bulkiness or visible lumps on the fabric.

For example, if sewing a button on a cotton shirt, a size 50 polyester thread provides sufficient strength and smooth stitches that pass through buttonholes and fabric easily. Conversely, if working with heavier materials like denim or canvas, consider a thicker thread, such as size 30 or 40, for added durability. On delicate fabrics like silk or chiffon, a finer thread sized 60 or above is preferable to prevent damage.

To decide on the thread size, examine the fabric’s thickness and the button's size. A larger button requires stronger thread, while a smaller button on lightweight fabric needs thinner thread for a clean look. Matching thread type (polyester, cotton, or nylon) to the fabric also matters for durability and appearance.

How Does Thread Size Affect the Strength and Appearance of a Sewn Button?

Thread size plays a significant role in both the strength and aesthetic of a sewn button. The thread must be resilient enough to withstand forces applied during buttoning and unbuttoning without breaking. At the same time, it should create neat stitches that blend with the garment.

For instance, if sewing a medium-sized button on a cotton shirt, using a size 40 polyester thread facilitates strong, secure stitches. The polyester material resists stretching and shrinking, ensuring the button stays attached through multiple washes. If a thread too fine (size 60 or higher) were used, it might snap when pressure is applied. Conversely, using an overly thick thread (size 20 or below) may create bulky stitches that look uneven and cause discomfort.

A properly sized thread also affects the button’s stability. A thread that fits well through the buttonholes leaves enough space for a thread shank — a small gap between the button and fabric — allowing the button to move slightly. This reduces fabric puckering and wear. The right thread size ensures the button sits flat and the repair looks professional.

Why Is Thread Size Important for Everyday Sewing Repairs?

Thread size matters because it affects how long the repair lasts and how the garment looks after sewing. Buttons are subject to frequent stress, especially on shirts or jackets, where pulling and tugging happen regularly. A thread that is too weak or thin will break, leading to repeated repairs and wasted time.

On the other hand, using thread that is too thick can cause damage to fine fabrics or create an unsightly finish. Overly bulky thread can pull the fabric, causing puckering or making the button sit unevenly. This not only reduces comfort but also shortens the garment’s lifespan.

For example, if sewing a button onto a cotton shirt that gets frequent use, choosing a size 40 polyester thread balances durability with subtle appearance. This thread resists wear from washing and everyday use, saving repeated mending and preserving the garment’s original look.

Using the correct thread size also saves money in the long run by extending the life of garments and reducing the need for professional repairs or clothing replacement. Knowing which thread size to use helps accomplish effective repairs quickly and with a neat, lasting result.

What Are Common Types of Thread and When Should They Be Used?

Understanding thread types complements the choice of thread size. Common thread types for sewing buttons include:

• Polyester Thread: Strong, slightly stretchy, and resistant to shrinking and mildew. Ideal for most fabrics and everyday clothing repairs.
• Cotton Thread: Natural fiber with a matte finish, best suited for sewing on natural fiber fabrics like cotton or linen. Less stretch but blends well on casual or vintage styles.
• Nylon or Silk Thread: Smooth and fine, used for delicate or specialty fabrics, such as silk garments or lingerie. Provides a fine finish but less durable under stress.
• Heavy-Duty Thread: Thicker than standard polyester, used for denim, leather, or canvas. Best for heavy buttons or outerwear.

Thread sizes typically range from about 12 (thicker) to 100 (very fine). Size 40-50 polyester thread is versatile and broadly suitable for button sewing on everyday clothing.

When sewing a heavy coat button, for example, heavy-duty polyester thread size 30 or 40 will provide the strength needed. For a fine silk blouse’s small button, a finer nylon thread sized 60 or above is better to avoid damage and visible stitching.

What Thread Size Should You Avoid When Sewing Buttons?

Avoid thread sizes that do not match the fabric and button conditions. Very fine threads (size 60 or higher) are too weak for buttons on everyday garments. They tend to snap under stress, leading to repeated repairs. Using these for heavy or medium buttons will result in poor durability.

Similarly, very thick threads (size 20 or below) should be avoided on lightweight or delicate fabrics. They create bulky stitches that can damage the fabric, cause puckering, and make the button look oversized or awkward.

For example, sewing a small button on a lightweight cotton shirt with thick size 20 thread can lead to bumps that show through the fabric and discomfort when wearing. Using a medium-size thread like 40 or 50 prevents these issues and yields a neat finish.

If unsure, it is safer to select a medium-weight thread size in the 40-50 range, especially polyester type, which balances strength and appearance for most common sewing repairs.

How to Sew a Button Using the Right Thread Size: Step-by-Step Instructions

Sewing a button with the correct thread size improves both security and appearance. Here is a clear step-by-step guide:

1. Cut the Thread: Cut about 18 to 24 inches of medium-weight thread (size 40 or 50). This length is easy to manage and reduces knots or breakage.
2. Thread the Needle: Use a sharp needle suitable for the fabric weight. Thread it and tie a small knot at the end.
3. Position the Button: Place the button exactly where it belongs on the fabric.
4. Start Sewing: Pass the needle from the back of the fabric through one buttonhole, then down through the opposite hole, pulling the thread tight but not too tight.
5. Repeat Stitches: Sew through the buttonholes and fabric 5 to 6 times to secure the button firmly.
6. Create a Shank: Before finishing, lift the button slightly and wrap the thread around the stitches beneath it 3 to 4 times. This forms a thread shank, allowing the button some movement to prevent fabric puckering.
7. Tie Off the Thread: Pass the needle to the back side of the fabric and knot the thread securely.
8. Trim Excess Thread: Cut the thread close to the knot.

This method ensures a strong, neat attachment that lasts. For more detailed guidance, see step-by-step tutorials on sewing a button on a shirt.

What Should You Do Next After Choosing the Right Thread Size?

Once the thread size is selected and your button sewing technique is clear, gather all necessary materials: the button, matching thread, a sharp needle, scissors, and the garment. Follow these practical steps:

• Double-check thread color matches the fabric or button for a discreet or decorative finish.
• Prepare a clean, well-lit workspace.
• Test your stitch tension on a scrap of the same fabric.
• Sew the button using the steps above.
• Inspect your work by buttoning and unbuttoning to ensure durability and comfort.
• If the button feels loose, sew additional stitches.

With practice, sewing buttons becomes faster and more reliable. For beginners, practicing on scrap fabric first is helpful. Parents and educators can support kids learning button sewing by following simple, clear steps designed for learners.

For further reading, explore detailed guides for beginners and examples of button sewing projects.

Frequently asked questions

Can I use any thread to sew a button?

While any thread can be used, choosing a medium-weight polyester thread sized 40 or 50 is best for durability and neat stitches on most garments. Avoid very fine or overly thick threads unless working with specialty fabrics or heavy-duty buttons.

How long should the thread be when sewing a button?

Cut about 18 to 24 inches of thread. This length is manageable to avoid tangling and breaking while sewing securely.

What if I use thread that is too thin for the button?

Thin thread may break under the stress of buttoning, causing the button to come loose quickly, requiring repeated repairs and extra time.

How do I create a thread shank when sewing a button?

After sewing the button securely, lift it slightly and wrap the thread around the stitches beneath the button 3 to 4 times before tying off. This creates a small gap allowing the button to move and prevents fabric puckering.

Should thread color match the fabric or button?

Matching thread color to the fabric usually makes the stitches less visible, but matching the thread to the button can highlight it if desired. Choose based on the look you want.

What needle should I use for sewing buttons?

Use a sharp hand-sewing needle appropriate for the fabric’s thickness. A size 7 or 8 needle works well for most medium-weight fabrics and buttons.