Button Size Calculator
Convert Ligne to mm/inches with 1:1 Scale Accuracy
Screen Calibration
Grab a standard credit/debit card. Adjust the slider below until the blue box represents the exact width of your card.
| Ligne | MM | Inch | Usage |
|---|
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Button Ligne Explained: A Complete Size and Conversion Reference
What is Button Ligne?
Ligne is a pre-metric French unit that has survived in the garment trade long after most other old world measurements were retired.
The word itself simply means line and it traces back to 18th-century European craftsmen particularly watchmakers and button manufacturers who needed a finer scale than what inches alone could offer.
For anyone working with buttons today, the two numbers worth memorizing are these: one Ligne equals 0.635mm and 40 Lignes make up exactly one inch (25.4mm).
Because buttons sit at such a small scale even a millimeter or two can change how a fastening looks and functions on a finished garment. The Ligne gives manufacturers and designers a shared language precise enough to catch those differences.
How to Use the Button Size & Ligne Converter
The converter accepts input in any of the three units — Ligne (L), millimeters (mm), or inches (in) and recalculates the remaining two the moment you type a value.
- Type your known measurement into whichever field matches the unit you're working in. The other two fields update automatically.
- Use the Calibration slider to set a true 1:1 preview. Screens differ in pixel density, so the tool can't assume your monitor's resolution. Hold a standard credit card up to the display and drag the slider until the on-screen card width matches the physical one. Once calibrated, the circular button preview reflects the button's actual diameter at real-world scale.
- Check the Nearest Standard Size result. Button manufacturers don't produce every conceivable diameter — production runs are built around set increments like 16L, 24L and 32L. This field tells you which industry-standard size your entered measurement falls closest to which is useful when you're sourcing replacements or specifying components in a tech pack.
The Math: Ligne to MM Conversion Formulas
All three conversion directions use straightforward arithmetic:
Converting Ligne to millimeters:
Converting millimeters back to Ligne:
Converting inches to Ligne:
These are the same formulas the tool runs in the background, so you can cross-check any result by hand or use them directly when filling out manufacturing specs.
Standard Button Size Chart & Common Use Cases
| Ligne (L) | Metric (mm) | Typical Application |
|---|---|---|
| 14L – 16L | 8.8mm – 10.1mm | Dress shirt fronts and collar button-downs |
| 18L – 20L | 11.4mm – 12.7mm | Trouser waistbands, flies, and childrenswear |
| 24L | 15.2mm | Suit and blazer sleeve cuffs, waistcoats |
| 30L – 32L | 19.0mm – 20.3mm | Suit jacket fronts and sport coat closures |
| 36L – 45L | 22.8mm – 28.5mm | Heavy outerwear — overcoats and pea coats |
Button selection isn't purely functional. The diameter has to feel proportional to the fabric weight, the lapel width, and the garment's overall silhouette. A 24L button that works perfectly on a lightweight vest would look undersized on a structured wool overcoat.
Why Visual Calibration is Critical
An unscalibrated on-screen circle is essentially useless for size reference. A 24L button preview on a 27-inch desktop monitor occupies far more pixels than the same circle on a phone screen, and neither one is accurate unless the tool knows your device's pixel density.
The calibration step fixes this. Once you've matched the credit card width on screen to your physical card, the tool calculates your monitor's actual PPI and scales the preview accordingly. At that point you can hold a real button next to the screen and the comparison is honest.
This matters most for home sewers tracking down a match for a loose button, and for pattern designers who want to see how a given diameter reads visually against a sketch before committing to an order.
Frequently Asked Questions (FAQ)
Where does the term Ligne actually come from?
It's the French word for line and was a standard unit across several precision crafts in 18th-century Europe including watchmaking and button manufacturing. It stuck in the garment trade even as the metric system displaced it everywhere else.
A button says 5/8 inch on the packaging — is that the same as 24L?
Close, but not identical. 24L converts to roughly 15.24mm while 5/8 inch comes out to 15.87mm. In casual sewing that gap won't matter, but in tailoring it can affect how cleanly a buttonhole closes, so it's worth confirming which spec your pattern was designed around.
I have a button with no label — how do I figure out its size?
Measure straight across the widest point of the button face using a caliper or a millimeter ruler. Enter that mm figure into the converter and it will give you the Ligne equivalent and the nearest standard size.
