About Us

Why Rings Sizer Exists

Ring sizing looks simple until you're actually trying to buy one — especially online, or across countries. A "size 7" in the US isn't a size 7 anywhere else; the UK uses letters, Japan uses its own numeric scale, and much of Europe just measures millimeters. Most sizing charts online show you one system in isolation and leave the conversion to you.

Rings Sizer was built to fix that: one tool that converts between every major system instantly, plus real measurement methods for when you don't already know your size in any of them.

What We Believe

• Free, no account required. Every tool works instantly, and anything you choose to save stays in your own browser, not on our servers.
• Accuracy over guesswork. Our conversion tables are built from standard internal-circumference and internal-diameter measurements used across the jewelry industry, not rough approximations.
• Honest about limits. Home measurement is a strong estimate, not a lab-grade fitting. We say so throughout the site, especially for purchases like engagement rings where getting it right matters most.

How the Tools Work

Every size on Rings Sizer traces back to two physical measurements: a ring's internal diameter and internal circumference. Whether you enter a US size, a UK letter, a Japanese number, or a measurement you took yourself with string or a ruler, we convert it through that same underlying scale, so the results line up with what a jeweler local to you would use.

Who's Behind Rings Sizer

Rings Sizer is maintained by a small team focused on making everyday sizing and measurement problems easier to solve online. We keep our sizing tables aligned with published industry standards and update the site as we learn where people get stuck.

Get in Touch

Found a conversion that looks off, or have a suggestion for a tool we should build? We'd like to hear it — reach us through the Contact page.