Ring Sizing Guide

Finding the perfect fit shouldn’t be complicated. All SAINT MERCURY rings are crafted from solid 925 sterling silver and designed with comfort in mind — many of our pieces feature slight adjustability to help you get your ideal fit.

Below is everything you need to know to choose your size with confidence.

How to Measure Your Ring Size at Home

Option 1 — Measure an Existing Ring

  1. Choose a ring that fits the finger you’ll wear your new piece on.

  2. Measure the internal diameter in millimetres (mm).

  3. Match the measurement to the chart below.

Option 2 — Measure Your Finger

  1. Wrap a thin strip of paper around your finger.

  2. Mark where the ends meet.

  3. Measure the length in millimetres — this is your finger circumference.

  4. Use the conversion chart to find your best size.

Fit Notes for SAINT MERCURY Rings

  • Many styles are slightly adjustable for comfort.

  • For longevity, gently adjust your ring only once to your ideal size.

  • We recommend choosing a size within the advised range on each product page for the best fit and structural integrity.

Ring Size Conversion Chart

Internal Diameter (mm) → Circumference (mm) → US Ring Size

US Size Finger Circumference Ring Diameter
3 44.20 mm 14.07 mm
3 1/4 44.80 mm 14.27 mm
3 1/2 45.50 mm 14.48 mm
3 3/4 46.10 mm 14.68 mm
4 46.80 mm 14.88 mm
4 1/4 47.40 mm 15.09 mm
4 1/2 48.00 mm 15.29 mm
4 3/4 48.70 mm 15.49 mm
5 49.30 mm 15.70 mm
5 1/4 50.00 mm 15.90 mm
5 1/2 50.60 mm 16.10 mm
5 3/4 51.20 mm 16.31 mm
6 51.90 mm 16.51 mm
6 1/4 52.50 mm 16.71 mm
6 1/2 53.10 mm 16.92 mm
6 3/4 53.80 mm 17.12 mm
7 54.40 mm 17.32 mm
7 1/4 55.10 mm 17.52 mm
7 1/2 55.40 mm 17.73 mm
7 3/4 56.30 mm 17.93 mm
8 57.00 mm 18.40 mm
8 1/4 57.60 mm 18.34 mm
8 1/2 58.30 mm 18.54 mm
8 3/4 58.90 mm 18.75 mm
9 59.50 mm 18.95 mm
9 1/4 60.20 mm 19.15 mm
9 1/2 60.80 mm 19.35 mm
9 3/4 61.40 mm 19.56 mm
10 62.10 mm 19.76 mm
10 1/4 62.70 mm 19.96 mm
10 1/2 63.40 mm 20.17 mm
10 3/4 64.00 mm 20.37 mm
11 64.60 mm 20.57 mm
11 1/4 65.30 mm 20.78 mm
11 1/2 65.90 mm 20.98 mm
11 3/4 66.60 mm 21.18 mm
12 67.20 mm 21.39 mm
12 1/4 67.80 mm 21.59 mm
12 1/2 68.50 mm 22.00 mm


Note: Sizes 6.5 and below typically resonate most with SAINT MERCURY customers, but your adjustable bands allow flexibility.)

Still Unsure of Your Size?

If you’re between sizes or unsure, we recommend choosing the larger size — or selecting an adjustable style for the best flexibility.

You can also reach out to us at support@dearsaintmercury.com and we’ll be happy to help.