What size should I choose if I'm between two sizes?

Always go smaller. A snug fit seals flush and lasts longer. A nail that's 0.5mm too wide lifts at the edges within days and traps moisture.

Why is there a gap at my cuticle line?

It's a sizing issue. The nail is too narrow for your nail bed. Size up one and the gap disappears.

Does the nail size tool work for wide and flat nail beds?

Yes. The tool measures your actual nail width, so it works for wide, narrow, flat, and curved nail beds alike. For flat nail beds, size up one and use gel tabs instead of glue.

Free Online Nail Size Tool: Measure Your Press-On Nail Size in 30 Seconds

Q: How do I measure my nail size without a ruler?

Use MOONLEE's free online nail measurement tool. Place a credit card on your screen to calibrate, hold your finger up, and get your exact size in 30 seconds. No ruler, no printing, no app.

Q: How do I measure my nail at home?

Use the free online nail measurement tool. Credit card on screen to calibrate, hold finger up, done in 30 seconds. No tape measure, no ruler, no printing. Works on any phone or desktop.

Q: Is there a nail calculator I can use online?

Yes. MOONLEE's free tool works as a nail calculator — your credit card calibrates the screen and gives you measurements in millimeters. Works on phone and desktop.

Q: How do I choose the right press-on nail size?

Measure the widest point of each nail bed. If between sizes, go smaller. For wide or flat beds, size up one and use gel tabs. Measure all 10 fingers — they're rarely all the same.

Q: Should I measure my dominant or non-dominant hand?

Measure all 10 fingers. Your dominant hand is typically 0.5mm wider — order based on your dominant hand measurements.

April 23, 2026|MoonLee

Measure Your Nail Size in 30s with a Creadit Card

TL;DR: No ruler needed. Use a credit card + this free online nail measurement tool. Done in 30 seconds. Measure now →

Why Fit Is Everything

The #1 reason press-ons fail isn't the glue. It's the fit.

Wrong size = gaps at the cuticle, lifting edges, nails popping off in a day. I see it in my DMs constantly. And almost every time, the person guessed their size because they didn't have a ruler.

So I built a free tool that fixes that. No app. No printing. No ruler. Just your phone and a credit card.

How to Measure Nail Size for Press-On Nails (30 Seconds)

Every credit card is the same size — 85.6mm × 54mm. The tool uses that to calibrate your screen, then you hold your finger up and get your exact nail width. This is the easiest way to measure your nail at home — no tape measure, no guessing.

Open the tool on your phone or desktop
Lay your credit card flat on the screen
Hold each finger up to the screen and match the edge
Write down all 10 fingers — your dominant hand is usually 0.5mm wider

👉 Open the free nail measurement tool →

The Golden Rule of Sizing

Between two sizes? Go smaller. A snug nail sits flat and holds longer. Even 0.5mm too wide and the edges start lifting within days — that gap traps moisture, which is exactly how greenies start.

One thing most people get wrong: they measure the tip instead of the widest point of the nail bed. Measure the widest point. That's the number that matters.

Sizing Tips by Nail Bed Type

Wide or flat nail beds: Size up one from your measurement, then use gel tabs instead of glue. Glue can't seal the side edges on flat beds — tabs flex where glue snaps off. If you've been struggling with press-on nails for wide nail beds, nine times out of ten it's the size, not the glue. → Glue vs Tabs guide

Narrow nail beds: Stick to your exact measurement. Don't size down for a tapered look — gaps at the sides collect moisture and the nail lifts fast. You want clean edges, no skin overlap on either side.

Small hands / pinky fingers: Measure every single finger. The pinky almost always surprises people. Press-on nails for small nails aren't one-size-fits-all — even within the same hand.

Moon🌙 Mailbag

How do I measure my nail size without a ruler?

Put a credit card on your screen, calibrate the tool, measure each finger. Accurate to ±0.5mm. No ruler, no printing, no app. Just do it on your phone right now.

How do I measure my nail for press on nails?

Open the tool, place your credit card on the screen to calibrate, then hold each finger up and match the edge. Always measure the widest point of your nail bed — not the tip. Record all 10 fingers, because they're rarely all the same size.

How do I measure my nail at home?

This tool is the easiest way. Credit card on screen → calibrate → hold finger up → done. No tape measure, no ruler, no printing. Works on any phone or desktop in about 30 seconds per hand.

What is the most accurate way to measure nails for press-ons?

Three methods: the on-screen tool (fastest), a soft tape measure around the widest point of your nail bed, or a paper strip + ruler. Always measure the widest point — not the tip.

Is there a nail calculator I can use online?

Yes — that's exactly what this is. Think of it as a nail calculator: your credit card calibrates the screen, you get your measurements in millimeters, and you know your size. Phone or desktop, both work fine.

Why is there a gap at my cuticle?

The nail is too narrow for your bed. Size up one and it's gone.

Does this tool work for wide nail beds?

Yes. It measures your actual nail width — wide, narrow, flat, curved, all of them.

How do I choose the right press-on nail size?

Measure the widest point of each nail bed. Between sizes, go smaller. Wide or flat beds, size up one and switch to gel tabs. And measure all 10 fingers — they're almost never all the same.