Ring Sizer: Size Measure App

Planning a surprise proposal but don't know their ring size? Ring Sizer turns your iPhone into an accurate ring measuring tool. Place a ring on the screen, size a finger, or use a simple piece of string — then read the US, UK & EU size in seconds. No printing. No guessing.

Your first measurement is free, and the Size Converter is always free to use. Unlimited measurements and saved sizes for your whole family require a Ring Sizer Pro subscription. A free trial is available.

Whether you're secretly sizing a partner's ring for an engagement, ordering a wedding band online, or checking your own finger before buying jewelry, Ring Sizer helps you find your size in under a minute — no jeweler visit required.

HOW IT WORKS
• On-Screen Ring Sizer — place any existing ring on your screen and match it to the adjustable circle for an instant reading
• Finger Size Finder — put your finger on the display and drag the sliders until they touch both sides
• String Method — no screen to calibrate? Wrap a piece of string or paper around your finger, enter the length, and get your size right away
• Size Converter (free) — convert any size between US, UK/AU, EU/ISO and Japanese standards, and switch between diameter and circumference in mm, cm and inches
• Instant Conversion Chart — see your measured result across every standard at a glance

PERFECT FOR A SECRET PROPOSAL
Borrow a ring they already wear (from the correct finger!), place it on the screen, and get the size in seconds. Put it back before anyone notices. The surprise stays a surprise.

WHY RING SIZER
• Calibrated to your device — the on-screen scale is matched to your exact iPhone model
• Every standard covered — full international ring size chart built in
• Save sizes (Pro) — keep your partner's, your own, and family members' sizes for future gifts
• Works offline — measure anywhere, no connection needed
• No printer and no jeweler visit required

BUYING JEWELRY ONLINE?
Online jewelry returns are often caused by one thing: the wrong size. Measure with Ring Sizer first, then order engagement rings, wedding bands, and everyday jewelry with more confidence.

TIPS FOR AN ACCURATE MEASUREMENT
• Measure at the end of the day when fingers are at their normal size
• Avoid measuring when hands are cold — fingers shrink
• If you're between two sizes, choose the larger one