What size press-on nails am I?
Measure the width of each nail bed in millimetres at its widest point, then match that measurement to a size on the chart below — a 12 mm nail is a size 4, an 11 mm nail is a size 5, and so on down to 7 mm for a size 9.
There is no single press-on size for a person. Every one of your ten nails gets its own measurement, your dominant hand is often a fraction wider than the other, and a set that fits nine nails and floats on the tenth will fail on the tenth. Five minutes with a strip of paper and a ruler is what separates a set that lasts three weeks from one that pops off in the car park.
Press-on sizes are numbered backwards from what most people expect: size 0 is the widest tip and the numbers get smaller as the nail gets smaller. Your thumb will almost always be your lowest number and your pinky your highest.
6 min read · Reviewed August 2026
The short version
- Measure the WIDTH of the nail bed in millimetres, sidewall to sidewall, at the widest point — not the length.
- Press-on sizes run backwards: 0 is the largest tip, 9 is the smallest.
- Typical measurements are 15–17 mm on the thumb, 11–13 mm on the index and middle, 10–12 mm on the ring and 8–10 mm on the pinky.
- Measure all ten nails. Left and right hands are frequently one size apart.
- Between two sizes, take the larger tip and file the sides down — you can remove material, you cannot add it.
- A tip that touches the skin at the sidewalls is too big and will lift; one that leaves your own nail showing at the corners is too small and will lift faster.
How to measure your nails (no sizing kit needed)
Cut a thin strip of paper, lay it flat across the nail, and mark where the nail meets the skin on each side — the distance between those two marks, read off a ruler in millimetres, is your size. Paper beats a ruler held against the finger because it wraps to the curve of the nail instead of measuring the chord across it, and the curve is where a millimetre gets lost.
Do this on a bare nail. Polish adds nothing, but a nail that has just been soaked is slightly swollen, so measure before a shower rather than after. If you normally push your cuticles back before applying, do that first too — it changes where the nail visibly starts by up to a millimetre on the thumb.
- Cut ten strips. Roughly 5 mm wide and 4 cm long, from ordinary printer paper. Ten strips means you never have to remember a number.
- Lay one across a nail. Flat against the nail plate at its widest point, which on most nails is just above the cuticle line and not at the free edge.
- Mark both edges. With a fine pen, mark exactly where the nail disappears into the skin on the left and on the right. Do not include the skin.
- Read it on a ruler. Flatten the strip and measure between the marks in millimetres. Round to the nearest half-millimetre.
- Repeat for all ten. Both hands. Write the numbers down thumb-to-pinky, left hand then right.
- Match to the chart. Look each millimetre figure up in the size chart below. You will usually end up with four or five different sizes across ten nails.
Press-on nail size chart: millimetres to size
Match each measurement to the nearest width in the chart; if your number sits exactly between two rows, take the wider tip (the lower size number) and file it down. These widths are the standard scale used across press-on sets, including ours.
| Size | Nail bed width | Usually fits |
|---|---|---|
| 0 | 16.5 mm | Thumb — large hands |
| 1 | 15.5 mm | Thumb — average hands |
| 2 | 14.0 mm | Thumb — small hands; middle finger on large hands |
| 3 | 13.0 mm | Index and middle — large hands |
| 4 | 12.0 mm | Index and middle — average hands |
| 5 | 11.0 mm | Ring — average hands; index and middle — small hands |
| 6 | 10.0 mm | Ring — small hands; pinky — large hands |
| 7 | 9.0 mm | Pinky — average hands |
| 8 | 8.0 mm | Pinky — small hands |
| 9 | 7.0 mm | Pinky — very small nail beds; children |
Which size goes on which finger?
Most people land on four or five different sizes across ten nails, in the pattern thumb → middle → index → ring → pinky from widest to narrowest. The table below is a starting point for a dry-fit, not a substitute for measuring: use it to sanity-check your own numbers, and trust the ruler if the two disagree.
Note the ordering quirk — on many hands the middle finger is very slightly wider than the index, so it takes the lower number. If yours are the same width, they take the same size, which is perfectly normal.
| Nail | Small hands | Average hands | Large hands |
|---|---|---|---|
| Thumb | 2 | 1 | 0 |
| Index | 5 | 4 | 3 |
| Middle | 4 | 3 | 2 |
| Ring | 6 | 5 | 4 |
| Pinky | 8 | 7 | 6 |
What to do if you are between two sizes
Take the larger tip and file the inside edges down until it drops into your nail bed — you can always remove material, and you can never add it. Filing a tip half a millimetre narrower takes about thirty seconds with the file in the box, and the result fits better than either stock size would have.
Going smaller is the mistake to avoid. A tip narrower than your nail bed leaves a strip of your own nail exposed along each sidewall, and that exposed edge is exactly where knocks land, water gets in and lifting begins. A too-narrow tip also looks obviously fake in a way a slightly-filed one never does.
There is a limit in the other direction too. A tip so wide that it presses into the skin at the sidewalls will ache within a few hours and lever itself off within a few days, because the skin pushes back constantly. If a tip is more than about a millimetre wider than your nail bed, drop a size rather than filing that much away.
- File the walls, not the underside. Run the file along the inner edge of the tip at the angle of your sidewall. Filing the underside thins the tip and it will crack.
- Dry-fit after every few strokes. Stop the moment the tip sits down flat without pressing into skin on either side.
- File before you glue, always. Filing a glued-on tip sends heat and vibration straight into the bond and into your nail plate.
- Remember it is permanent. A filed tip stays filed for every future wear, so if you plan to re-wear the set, file conservatively.
How to check the fit before you glue
Press each tip on dry and look at it from three angles: down the finger, from the side, and straight on. A correct tip spans the nail bed sidewall to sidewall without touching skin, sits flat with no rocking, and stops just short of the cuticle without overlapping it.
Rocking is the one people miss. If a tip pivots side to side under light pressure, the curve of the tip does not match the curve of your nail, and no amount of glue will fix a curvature mismatch — it will hold for two days and then release all at once. Try the next size in either direction; a different width usually brings a different curve with it.
Why sizing is the thing that actually decides wear time
Wrong size is the most common reason a press-on set fails early, ahead of glue technique and well ahead of glue quality. Everything about the bond depends on continuous contact between the tip and the nail plate, and a mis-sized tip breaks that contact at the edges before you have even applied it.
It is also the cheapest problem to fix. Prep technique takes practice, glue quantity takes a couple of sets to judge, but sizing takes five minutes with a strip of paper and it is right forever. Write your ten numbers down somewhere you will find them again — they will not change.