Button Measurement & Replacement Guide

How to measure a replacement button

1. Use a remaining button from the same position on the garment, or the original button if you still have it. A cuff or decorative button may differ from a front fastening.
2. Lay a round button flat beside a ruler marked in millimetres, or use calipers. Line up one outside edge with zero.
3. Measure straight across the centre to the opposite outside edge. This widest edge-to-edge distance is the diameter; do not measure just the recessed centre or the holes.
4. For an oval or irregular button, record both the longest and shortest widths and its outline. One diameter value cannot fully describe that shape.
5. Write down the measurement in mm, then compare it with the replacement’s verified specifications. Do not estimate size from a photograph without a scale.

One millimetre (mm) is one tenth of a centimetre: 1 cm = 10 mm. A diameter describes the width across a round button, not its thickness or the distance between its holes.

What is ligne, and how does it relate to mm?

In button sizing, ligne (often written L) is a traditional diameter unit: 1 L = 0.635 mm, or 1/40 inch. To convert a ligne size to millimetres, multiply by 0.635. To convert millimetres to ligne, divide by 0.635.

Supplier charts may round nominal sizes. A listed size is not a substitute for checking the finished button and its verified measurement. These examples do not assign a ligne size to any item in our collection.

Identify how the original button attaches

Sew-through / visible holes

Thread passes through holes in the button’s face. Compare the number and arrangement of holes, their spacing and the way the original is sewn.

Shank

A loop or raised attachment on the back holds the thread. Check its opening and the clearance between the button and fabric. A sewn thread shank can also provide spacing beneath a sew-through button.

Other attachment styles

A fixed post, rivet or other fastening needs its own matching construction and installation method. Do not assume that a sew-through replacement can be fitted in the same way.

Inspect the back as well as the face. A similar-looking front does not establish an equivalent attachment.

Why thickness and clearance matter

Buttons with the same diameter can have different profiles. A thicker button may be harder to pass through an existing buttonhole; its profile and the space beneath it can affect how the overlapping fabric strip, or placket, sits.

Compare the original’s thickness, the fabric layers and any shank clearance. A replacement should fasten without forcing the buttonhole or pulling the placket out of shape. Diameter alone cannot establish that fit.

Compare hole spacing and attachment style

For a sew-through button, compare the distance between hole centres and the hole arrangement with the original. If the replacement needs a different stitch layout, do not assume the old stitches or a machine’s existing settings will suit it.

For a shank, compare the loop and its height rather than a face-hole measurement. Keep attachment checks separate from colour and finish preferences.

Choose from the original, not appearance alone

First compare verified dimensions and the attachment. Then consider how the replacement will work with the existing buttonhole and fabric. Finally choose the appearance you prefer. If the needed thickness, hole spacing or other specification is unknown, ask for clarification before relying on a match.

Count the buttons you actually need to replace. Check the selling unit and pieces per pack; a pack quantity is not a recommended button count for a particular garment.

Before you order

• Check the selected option and its SKU, price, currency and availability.
• Check whether the price is per piece, pack or set, and how many pieces that unit contains.
• Compare verified diameter, thickness, holes or shank details with your original.
• Separate option labels from confirmed material, finish and physical specifications.
• Check any stated compatibility limits, delivery eligibility, shipping charge and returns policy.

When browsing the replacement-button collection, consult the verified specifications for each option. The product name and style labels do not by themselves verify hole count, shape, material or finish. Unknown fields remain unknown.

Measurement and sewing references

For the button-sizing unit, see U.S. Customs and Border Protection: Buttons. For flat and shank construction and sewing methods, see University of Florida IFAS: Sewing on a Button. These references explain general button knowledge; they do not verify our products.