The short answer: measure the inside diameter of a ring that already fits you, in millimeters, and match it to a US size. If you would rather measure the finger itself, wrap a thin strip of paper around the base, mark where the ends meet, and measure that length — that number is your circumference. Either way it takes about two minutes, and you do not need a printer.
Why the number matters more than the ring
A ring is the one piece of jewelry that has to fit an exact millimeter. A bracelet can be adjusted, a necklace can be shortened, and earrings are one size — but a ring either goes on or it does not. Ordering the wrong size is the most common reason a jewelry order goes back, and it is almost entirely avoidable with a ruler and two minutes.
It also matters because sizing is not universal. A US 7 is not a EU 7 or a UK N. If you are working from a size someone told you once, check which system it came from before you order.
Method 1 — Measure a ring you already own
This is the method we recommend, because it takes your finger out of the equation entirely.
- Take a ring that fits the finger you want to size. Wear it for an hour first if you can — a ring that fits in the morning can feel tight by evening.
- Lay it flat on a table and put a ruler across the middle.
- Measure the inside diameter: the distance from the inner edge on one side to the inner edge on the other. Do not include the band itself.
- Write the number down in millimeters.
- Match it to the chart below.
If the ring is not perfectly round — an open band, or a much-worn favourite — measure across the widest point and the narrowest, and use the average of the two.
Method 2 — Measure your finger
- Cut a strip of paper about 1 cm wide, or use a piece of cord that does not stretch.
- Wrap it around the base of your finger, just below the knuckle. Snug, but not tight enough to leave a mark.
- Mark the exact point where the end meets the rest of the strip.
- Lay the strip flat and measure from the end to the mark, in millimeters. That is your finger's circumference.
- Match the circumference to the chart below — or send us the number and we will tell you the size.
Ring size chart: US to millimeters
| US size | Inside diameter | Inside circumference |
|---|---|---|
| 5 | 15.7 mm | 49.3 mm |
| 6 | 16.5 mm | 51.9 mm |
| 7 | 17.3 mm | 54.4 mm |
| 8 | 18.2 mm | 57.2 mm |
| 9 | 18.9 mm | 59.5 mm |
| 10 | 19.8 mm | 62.2 mm |
| 11 | 20.6 mm | 64.7 mm |
| 12 | 21.4 mm | 67.2 mm |
Measure the inside of your ring, not the outside. The band itself is roughly 2 mm thick, so reading across the outside will put you one to two sizes too big.
Five things that change the answer
- Time of day. Fingers are smallest in the morning and largest at the end of the day. Measure in the afternoon or evening.
- Temperature. Heat makes fingers swell and cold makes them shrink. Do not measure straight after a hot shower, a workout, or coming in from the cold.
- Band width. A wide band covers more of the finger and feels tighter than a slim band of the same size. If you are choosing a wide style, size up half to one size.
- Your knuckle. If your knuckle is wider than the base of your finger, measure both and pick a size that clears the knuckle comfortably. A ring you cannot get past the knuckle is worse than one that spins slightly.
- Which finger, and which hand. Your dominant hand is usually slightly larger, and index and middle fingers are bigger than ring and little fingers. Always measure the exact finger you plan to wear it on.
Between two sizes? Go up, not down
A ring that is a little loose sits comfortably and stays where it should. A ring that is a little tight is uncomfortable within an hour, and it only gets worse as the day goes on. If your measurement lands between two sizes, choose the larger one.
Five mistakes that lead to the wrong size
- Measuring with stretchy string. Elastic stretches as you pull it, and your measurement grows with it. Use paper or non-stretch cord.
- Measuring first thing in the morning. Your fingers are at their smallest then, and you will order a size too small.
- Reading the outside of the band. It is about 2 mm wider than the inside, which is one to two full sizes.
- Borrowing a size from another finger. Finger sizes vary by up to two sizes across a single hand.
- Rounding to a whole number. Half a millimeter is the difference between two sizes. Keep one decimal place.
BOROWSKI sizing
Most BOROWSKI rings come in US 6 to US 9. Our wide 4-prong ring starts at US 5, and the black onyx dome ring runs from US 7 to US 12. Every product page lists the sizes available before you add it to your bag, so you can check before you commit.
If you would rather skip the question altogether, the adjustable open band fits US 6 to US 8 and needs no sizing at all. It is the safe choice when you are buying for someone else.
Still unsure? Email your measurement to support@borowskijewelry.com and we will tell you which size to pick. We reply within 24 hours, Monday to Friday.
Frequently asked
Can I measure a ring size without a ruler?
You can get close with a bank card: the long edge of a standard card is 85.6 mm, which is enough of a reference to judge a diameter. For anything you plan to order from, a ruler is worth finding.
What if I order the wrong size?
You can request a return or exchange within 14 days of receiving your order. Email support@borowskijewelry.com with your order number and we will send the return address and next steps.
Is my ring size the same on every finger?
No. Sizes commonly differ by one to two sizes between fingers on the same hand, and the hand you write with is usually slightly larger.
Do wide bands fit differently?
Yes. A wide band has more contact with your finger, so it feels tighter at the same size. If you are choosing between a slim and a wide style, size up for the wide one.
Should I measure in the morning or the evening?
The evening. Fingers are at their smallest in the morning and their largest at the end of the day, and a ring that fits in the morning may feel tight by the afternoon.