Press-On Nail Size Guide
Getting your size right is the difference between a set that looks like a salon manicure and one that looks applied. It is also the main reason nails lift early. The good news: this is a one-time job. Nail bed width does not change, so measure once, save the numbers, and every set you buy afterwards fits first time.
The one rule that matters most
When you fall between two sizes, always go down.
An oversized nail leaves an open channel along each side wall. Water works into it every time you wash your hands, the adhesive softens from the edges inward, and the nail lifts — usually around day four. An undersized nail leaves a thin strip of natural nail visible at the sides, which is only cosmetic. The bond stays intact.
Small is a look. Large is a failure.
How to measure — the tape method
This takes about five minutes and is the most accurate approach, because your nail is curved and a ruler held above a curved surface always under-measures.
- Lay a strip of clear tape or paper flat across one nail, at the widest part of the nail bed
- Mark where the nail meets the skin on each side
- Peel the strip off, lay it flat against a ruler, and measure between the marks
- Write the number down in millimetres
- Repeat for all ten fingers
Measure both hands. Most people have at least one finger that differs between them, usually the ring or little finger.
How to measure — the ruler method
Faster, slightly less precise.
- Rest a millimetre ruler directly on the nail at its widest point
- Read the width from one side wall to the other
- Add roughly 0.5 mm to account for the curve
- Repeat for all ten fingers
Three things that ruin a measurement
- Measuring the nail instead of the nail bed. You want the width of the bed where the press-on will sit, not your grown-out free edge.
- Measuring at an angle. Straight across at the widest point, never diagonally.
- Measuring one hand only. Hands are rarely symmetrical.
Understanding the size numbers
Sets come in two formats, and the difference matters more than anything else on this page.
A 24-nail set contains numbered sizes, usually 0 to 11, with two of each. The numbering runs counter to intuition: 0 is the largest, 11 is the smallest. Size 0 is typically a thumb, and the numbers climb as nails get smaller toward the little finger.
A 10-nail set contains exactly one nail per finger. There are no duplicates and no spares.
Check which format you are buying. The tip count is stated on every product page.
A typical hand uses two or three different sizes. If you find yourself using the same size on four fingers, re-measure — that usually means something was rushed.
Always dry fit before you glue
Lay out all ten nails, matched to the correct fingers, before you open the adhesive. Check three things on each one:
- Length to the cuticle — does it reach the cuticle line without overlapping the skin?
- Width — does it cover the full nail bed without pressing into the side walls?
- Rocking — does it sit flat, or does it tilt when you press one side?
That last check is the one most people skip. If a nail rocks, the curvature is wrong, not the width. Try the same size from a different position in the tray — curvature varies within a single set. A rocking nail will lift no matter how carefully you glue it.
When nothing fits quite right
Slightly too wide? File the side edges of the press-on with a fine file, two or three passes per side, testing as you go. This is normal practice, not a compromise.
Slightly too narrow? Use it. Position it centrally rather than pushing it to one side.
Too long from cuticle to tip? That is length, not size. File the tip down before applying, never after.
Never file your natural nail down to fit an oversized press-on. You would be removing keratin you cannot replace, to solve a problem a smaller size solves for free.
A note on thumbs
Thumbs are the most common sizing failure — they are the widest, the flattest and the most variable between people. If your thumbs are consistently the first nails to lift, they are almost certainly one size too large.
Save your sizes
Keep a note on your phone. Something like:
Left — thumb 16 mm, index 12 mm, middle 13 mm, ring 12 mm, little 9 mm
Right — thumb 16 mm, index 12 mm, middle 13 mm, ring 11 mm, little 9 mm
Then add a line for each brand you buy, noting which size numbers you used. Your millimetre measurements are permanent. Brand size numbers are not — conventions are similar but dimensions vary, so dry fit any new brand once.
Finally, keep your leftover nails. A 24-nail set for 10 fingers leaves spares in exactly the sizes you use — you can afford one mis-fit and try again. Store them in the original tray, in size order.
A 10-nail set has none. Every nail is committed the moment you glue it. On those sets, dry-fit all ten before you open the glue, and if one sits slightly wide, file the sides rather than reaching for another size — there isn’t one.
Still unsure? Read the full sizing guide or get in touch and we will help you find your fit.