Find your ring size — accurately or secretly

Free tool for finding your ring size with three approaches: direct finger measurement, detective methods for secretly estimating someone else's size, and AR camera try-on. Every result converts automatically across US, UK, EU, JP, RU, CN, IN and AU sizing systems.

How to Find Your Ring Size

Calibrate your screen

Match the on-screen card to a real credit card so every measurement is accurate to a fraction of a millimetre.

Pick a method

Choose Direct if you can measure your own finger, Detective to estimate someone else's size, or AR to try a virtual ring on camera.

Enter the measurement

Follow the on-screen guide: wrap a string, match a circle, or trace a ring. The result updates instantly.

Read the result with confidence

The card shows your size in every country's system plus a honest confidence range so you know how sure to be before buying.

Measure, estimate or try rings on virtually — every country supported

Screen calibration Calibration saved How do I calibrate? ▾

Match the card width to a real card on your screen so measurements are accurate.

Credit / ID card (85.6 × 54 mm):

TIMBRICA

Drag the slider until the image matches the size of the real object on your screen.

Direct

Choose a method

Measure the length of the paper where it just meets itself (not overlapping).

Measured length

Drag the slider until the circle exactly matches the inside of your ring.

Ring inner diameter: 17.0 mm

Lay your finger across the circle at the place you'd wear the ring. Drag to match the width.

Finger width at ring position: 18.0 mm

This PDF has a calibration square — print at 100% (no scaling).

I know my size in

Size

🕵️ Detective

Pick a detective method

Trace the inside circle of the ring on paper. Place the paper on the screen, then drag the slider until the circle matches.

Ring inner diameter: 17.0 mm

Measure the width across the imprint from the inside edge to inside edge (the ring's inner diameter).

Imprint inner width

I know the size of

I want to know

Known size (US / Canada)

Known size on other hand (US / Canada)

Which hand is dominant?

The known size is on the

Sex

Height

Weight (optional)

Glove size (optional)

Shoe size, US (optional)

ℹ️ Based on public datasets (NHANES + ANSUR II). Accuracy ±1 size. Use a direct method when possible.

Pick strategies that fit your situation. Tap each step to mark it done. Your progress is saved in this browser only.

0 / 8

🪞 Virtual ring try-on

Grant camera access, hold your hand in front of the camera and a ring will appear on your ring finger.

Camera access needed

Camera access is needed for hand tracking. Processing runs in your browser via WebAssembly.

Place a card next to your hand for best accuracy, then hold the gesture still for 2 seconds.

Your result

Fill in the fields to see your size.

🌡️ Swelling factors

Fingers swell up to half a size larger depending on time, temperature and diet. Tell us when you're measuring for a smarter result.

Time of day

Temperature

After activity

Conditions are neutral — the measurement should be accurate.

📐 Ring width

Wider rings need a larger size to slide over the knuckle comfortably.

💑 Couples mode

Enter measurements for both partners side by side. Great for matching wedding bands.

Partner A

Measured length (mm)

Partner B

Measured length (mm)

🌍 International size chart

The inner diameter and circumference of the ring in every common system.

Diameter (mm)	Circumference (mm)	US / Canada	UK / Australia	EU (ISO)	Japan	Russia

Features

5 direct methods: string, existing ring, finger on screen, printable sizer, known-size converter 6 detective methods including tracing, imprint, adjacent-finger and anthropometric estimates AR try-on with real-time hand tracking — no app install, runs fully in the browser Screen calibration, swelling advisor, comfort-fit, couples mode and printable export

Frequently asked questions

How accurate is the calculator?

Direct methods (string, ring, finger on screen, printable sizer) are accurate to about ±¼ size when the screen is calibrated. Detective methods are ±½ size and the anthropometric estimate is ±1 size — we show the confidence range on every result.

Is there a best time of day to measure?

Yes. Fingers swell during the day and in heat. The most reliable reading is early afternoon at a comfortable temperature. The swelling advisor above adjusts the result based on when you measured.

Can the ring size differ between my left and right hand?

Almost always. The dominant hand is typically half a size larger than the other. If you know the size on one hand you can pick the Other hand method to get the estimate for the opposite hand.

What if I have wide knuckles?

The ring needs to pass the knuckle but rest at the base of the finger without sliding off. Measure both, and either pick the knuckle size or use a European shank to secure the ring in place.

Is the AR try-on accurate?

The visual overlay is accurate enough to compare ring styles. Size inference from camera alone is an estimate (±½ size) — for precise sizing, hold a card next to your hand for reference or use a direct method.

💡 Want us to improve this tool just for you?

We can — and it's free! Just send us a quick message with your idea. If you'd like to discuss it in detail, leave your email and we'll get back to you. You can stay anonymous.

How do you rate this tool?

Thank you for your rating!

Change my rating

Want to leave a comment?

Want to share more? Leave a comment!

Thank you! Your comment will appear after moderation.

Who is this tool for?

💍 Jewelry & Watches

Published 15 Apr 2026 Updated 01 May 2026