How to Measure Your Ring Size
You don't need a jeweler to find your ring size. With a piece of string, a ruler, and five quiet minutes, you can measure accurately enough to order with confidence whether you're buying for yourself or planning a surprise.
This guide walks you through the two methods that actually work at home: the string-and-ruler method for measuring a finger directly, and the existing-ring method for sizing from a ring you already own. We'll also cover the small details that throw measurements off, so you don't end up with a ring that spins on your finger or won't go past your knuckle.
If you need the full size conversion chart (US, UK, EU, mm) or guidance for buying a surprise engagement ring, those live on our main ring size guide. This page is focused on one thing: getting an accurate measurement at home.
Why an accurate measurement matters
A ring that's half a size off becomes a daily problem. It spins on your finger, slips when your hands are cold, or pinches by evening and you notice it every time you look down.
The stakes are higher with certain designs. Eternity bands, channel-set rings, and full-pavé settings have stones running around the band, which leaves little or no metal to work with on a resize. Some can't be resized at all without rebuilding the ring.
EthicStone rings are made to order in your exact size, not pulled from inventory. That makes the number you give us at checkout the size you live with. Five careful minutes now is worth getting right.
Here's the first method.
Method 1: The Paper Strip Method
If you don't already own a ring that fits the right finger, this is the most accurate way to measure at home. You need three things: a thin strip of paper, a pen, and a ruler with millimetre markings. Five minutes, careful technique, and you'll have a number you can trust.
What you'll need
- A thin strip of paper (about 1 cm wide, 10 cm long) — not string, which stretches and gives a false reading
- A pen
- A ruler with millimetre markings
Cut your paper strip
Cut a clean strip about 1 cm wide and 10 cm long. Printer paper works well — thick cardstock adds bulk that throws off the reading.
Wrap it around the base of your finger
Wrap the strip snugly around the base of the finger you're sizing for, where the ring will actually sit. Snug means flush against the skin, not compressing it.
Mark where the paper overlaps
Use the pen to mark the exact point where the paper meets itself after one full wrap. Be precise — a 1 mm error here translates to roughly half a ring size.
Measure the length in millimetres
Unwrap the strip, lay it flat against the ruler, and measure from the starting end to your mark. This number is your finger's circumference.
Match it to your ring size
Match your circumference to our International Ring Size Chart to find your size in US, UK, EU, or Japanese sizing. A circumference of 52 mm is a US 6, for reference.
View the Ring Size ChartCommon mistakes to avoid
- Pulling the paper too tight (gives a falsely small reading)
- Measuring with cold hands (fingers shrink in cold weather)
- Measuring once and trusting it (measure 2–3 times across different days, take the average)
Method 2: Measuring an Existing Ring
If you already own a ring that fits the right finger well, you can skip the string entirely. This method is also the go-to approach for surprise proposals. You borrow a ring from your partner's jewelry box, measure it, and put it back.
What You'll Need
- A ring you (or your partner) currently wear comfortably on the correct finger
- A ruler with millimeter markings, or printable calipers
- A ring size chart
Step-by-Step Instructions
- Pick the right ring. It needs to fit the same finger you're sizing for. A ring worn on the index finger won't tell you the right size for the ring finger. Make sure it's a ring that fits well now not one that's loose or that you've stopped wearing because it's tight.
- Place the ring on a flat surface. Lay it down so you're looking at it from above, like a circle.
- Measure the inside diameter in millimeters. Use a ruler to measure straight across the inside of the ring, from one inner edge to the opposite inner edge through the center, not at an angle. This is the diameter, not the circumference.
- Take the measurement three times at different angles across the circle. Many rings aren't perfectly round, especially older or worn ones. Use the average.
- Convert diameter to ring size. A 17.3mm inside diameter is roughly a US 7. Use our conversion chart for the precise match.
Tips for the most accurate measurement
These seven adjustments separate a measurement that's close from one that's right.
| Tip | Why it matters |
|---|---|
| Measure at the end of the day | Fingers reach their largest size in the late afternoon and evening; a morning reading can run a half-size small. |
| Measure at room temperature | Cold shrinks fingers, heat swells them — avoid measuring straight after a workout, hot shower, or coming in from cold weather. |
| Avoid measuring after salty food or alcohol | Both cause water retention, which makes fingers read up to a half-size larger than your true everyday size. |
| Measure 2–3 times across different days | Daily fluctuation of 1–2 mm is normal; take the average across readings for a number you can trust. |
| Account for your knuckle | If your knuckle is wider than the base of your finger, choose a size between the two so the ring clears the knuckle without spinning at the base. |
| Consider band width | A 6 mm band fits noticeably tighter than a 2 mm band in the same size; for any band wider than 4 mm, size up by half a size. |
| When in doubt, size up | A slightly loose ring can be resized down or worn with an adjuster; a ring that won't pass the knuckle is unwearable from day one. |
Frequently asked questions
For first time measurement, the paper strip method is most accurate: wrap a 1 cm-wide paper strip around the base of your finger, mark the overlap, and measure the length in millimetres. If you already own a ring that fits the same finger and hand, measuring its inside diameter is faster and slightly more reliable.
Use paper. String stretches under tension, which gives you a circumference larger than your actual finger sometimes by a full ring size. A thin strip of printer paper, around 1 cm wide and 10 cm long, holds its shape, marks cleanly with a pen, and gives a reading you can trust.
Size up. A slightly loose ring can be worn with an adjuster or resized down by a jeweler, but a ring that won't pass your knuckle is unwearable. Fingers also swell through the day and in warm weather, so the larger size is closer to your real average than the smaller one.
Your fingers fluctuate by 1–2 mm daily based on temperature, hydration, salt intake, and physical activity. They're smallest in cold mornings and largest in late afternoons or after exercise, salty meals, or alcohol. For the most reliable reading, measure in the evening at room temperature when your hands feel normal.
Yes. A wider band sits tighter on your finger because more metal contacts your skin. A 6 mm band in size 7 will feel snugger than a 2 mm band in size 7. For any ring with a band wider than 4 mm, size up by half a size for a comfortable fit.
Most can. Solitaires, three stone rings, and partial-pavé designs qualify for resizing. Eternity bands and full-pavé settings have stones running around the entire band, so they can only be remade not resized and we recommend getting your size right upfront. Reach out before ordering if you're unsure.