Control starts with fit.

Two minutes and a strip of paper.
Find the size that disappears on your finger.

Measure it right — the 2-minute guide.

When to measure, how to wrap, and how to judge the fit like we do — 3 short steps before you commit to a size.

Line drawing of a hand wearing the KiWear Ring on the index finger
Before you measure

Wear it on your dominant index finger.

The sensors sit in a fixed layout inside the band, and the gesture engine is tuned for one position: the index finger of the hand you write and swipe with. Worn there, every gesture reads clean and control feels immediate — so that's the finger to measure.

Your two index fingers can differ by a full size. Always go by your dominant hand.

Move it to your middle, ring or little finger and every gesture stops working — swipes, pinches, circles and traces all rely on the sensors sitting where they expect. Health tracking would carry on, but skipping a track, turning a page and handing off between devices would not.

Five ways to get it right.

Fit is where control starts, so we take sizing seriously. Quick or certain — every path below ends at the same place: a ring that disappears on your finger.

01 · Instant match

Measure once. We match the size.

Wrap a strip of paper around your dominant index finger, mark where it overlaps, and enter the length — we turn it into your US size.

Dominant index finger
Recommended size
US 8
02 · No ruler needed

Print the true-scale sizer.

A one-page PDF with every size marked at exact scale. Print at 100%, cut the strip, wrap it — and read your size straight off your finger.

Check the 80 mm bar on the page before you trust it — accuracy is the whole point.

Download the PDF sizer
03 · Got a 3D printer?

Print the try-on set yourself.

Ten ring models, US 6–15, each with its size marked on it. Print two adjacent sizes, wear them on your dominant index finger, and shake-test the fit — a real ring you can judge today, for a few grams of filament.

A printed ring grips far less than the real one, so the fit is settled by a shake test, not by how it feels. Read the guide before you print.

Download the models
04 · Certainty Coming soon

Try every size at home.

The KiWear Sizing Kit is a full try-on set, US 6–15 — wear your closest sizes through a real day and lock the exact fit before we make yours.

KiWear Sizing Kit — the full try-on set, US 6–15

05 · Got other questions? Reach us at contact@kiwear.com, or join our community: kiwear.com/discord

contact@kiwear.com Join our Discord

KiWear Ring — true-scale sizer

Print at 100% — turn off “fit to page”. Check the scale bar below: it should measure exactly 80 mm before you start.

Wrap the strip around your dominant index finger

KiWear Ring is worn on the index finger of your dominant hand — the one you write and swipe with — because the sensors inside the band are laid out for that position. Measure that finger only: your two index fingers can differ by a full size. It fits your middle, ring or little finger too and health tracking keeps working there, but gesture control does not.

Cut out the strip below along its dashed edge. Wrap it around the base of that finger — snug, not tight — starting from the 0 edge, and read the size where the strip overlaps. If your knuckle is wider than your finger base, wrap the knuckle instead and use that size.

  • Measure in the evening, 6–9pm — fingers sit at their natural daily peak. Re-check the next morning.
  • Keep your arm relaxed at your side and your hand loose; measure your dominant index finger, not another finger or your other hand.
  • Whole US sizes only. Land between two marks? Always take the larger size.
  • The right fit clears your knuckle, sits steady through your day, and leaves no mark after two hours.
Sizing guide

Measure it right.

Two minutes of care here buys years of a ring you never notice. Three steps, then you’re done.

Step 1 Pick your moment

Measure in the evening, between 6 and 9pm — fingers sit at their natural daily peak, closest to how the ring will live on you. Re-check the next morning to see your range.

Skip it right after a workout, a hot shower or time in the sun, and when your hands are cold, stiff or swollen — those readings lie.

Step 2 Measure the right finger, the right way

The right finger is the index finger of your dominant hand — the one you write and swipe with. KiWear Ring is made to be worn there, and every gesture is tuned for it. Left and right index fingers often differ by a full size, so measuring the other hand, or another finger, will land you on the wrong number.

Arm relaxed at your side, hand loose. Clenching or holding your hand up drains the blood and reads small.

Wrap snug, not tight, at the base of the finger; if your knuckle is wider than the base, measure the knuckle and size to it.

Step 3 Judge the fit like we do

The right size slides over your knuckle without forcing, sits steady through typing, lifting and sleep, and leaves no mark after two hours of wear.

KiWear uses whole US sizes only. Land between two? Always round up — the sensors need contact, your skin needs room. A squeeze is never the right answer.

For your hands

  • Wide knuckle, slim base — size to clear the knuckle; a little play at the base is normal.
  • Active, or prone to swelling — size to your swollen peak and round up, so there’s room when hands warm up.
  • Slim fingers — measure relaxed, don’t cinch tight, or the ring will spin and slip.
  • Sweaty hands — dry off first, then pick the standard snug size so it stays put.

A finger can shift a full millimetre through the day — and that millimetre is the line between a ring that disappears and one you can’t wait to take off.
3D printing

Print it, then shake it.

Two things decide whether this works: print it at 100% scale, and judge it by the shake test — never by how it feels.

The shake test

The real ring is filled with potting resin and grips your skin far more than plastic does. A print will always feel looser than the real thing — so the feel tells you nothing. Whether it stays on tells you everything.

  1. Print two adjacent sizes: the one the finder gave you, and the size below it.
  2. Wear one on your dominant index finger.
  3. Shake your hand hard — about 30 shakes, five seconds.
  4. Stays on? That's your size. Both stay on? Take your pick — a little room, or an exact fit.

Print settings

  • 100% scale — turn off auto-fit and shrink compensation. The dimensions are the measurement.
  • 0.15–0.2 mm layers, flat on the bed, no supports. PLA, PETG or resin.

A print is a reference, not a guarantee. Unsure, or neither size holds? Send your measurement to contact@kiwear.com.
Sizing Kit

Try every size at home.

The KiWear Sizing Kit — a boxed try-on set of rings in every size
Coming soon
  • The full range, US 6–15 — a complete try-on set, so you test each size on your dominant index finger — the finger you'll actually wear it on.
  • Lock in your size — confirm the one that fits before you order.
  • Made for the unsure — tricky fingers, or anyone who'd rather be certain than guess.

How you'll know it fits

  1. Slides over your knuckle easily — no catching, no squeezing.
  2. Sits steady through everyday wear — no wobble, no soreness, no pressure.
  3. After two hours of continuous wear: no marks, no discomfort.

The fit, settled.

Which finger do I measure?

The index finger of your dominant hand — the one you write and swipe with. KiWear Ring is made to be worn there, and every gesture is tuned for that finger. Your left and right index fingers can differ by a full size, so measure the hand you'll actually wear it on; don't use another finger as a stand-in.

How do I find my size?

Wrap a strip of paper around your dominant index finger, mark where it overlaps, and measure the length in millimetres — the size finder above turns it into your US size. If you have a printer, the true-scale sizer (PDF) prints that strip with every size marked at exact scale, so you can read your size straight off your finger. With a 3D printer, you can go further and print the try-on rings themselves.

I already wear a smart ring — can I order the same size?

Use it as a reference, not a rule. Smart ring sizes aren't interchangeable — brands cut their sizes differently, so your usual number may match your KiWear size or sit one size off. The true-scale paper sizer settles it in two minutes; or reach out with the ring you wear now and we'll recommend your size.

When's the best time to measure?

Evening, 6–9pm, when your fingers sit at their natural daily peak — then re-check the next morning. Skip it right after exercise, a hot shower, or when your hands are cold or swollen. Keep your arm relaxed and hand loose, and measure the exact finger you'll wear it on.

Can I 3D print a sizer?

Yes — the sizing tools above include a free download with all ten ring models, US 6–15, so you can print real try-on rings at home. Two things to know: print at 100% with every scaling option off, and don’t judge them by feel. The real ring is filled with potting resin inside the band and grips far more than a printed model, so a print will always feel looser than the real thing. Wear it, shake your hand hard about 30 times, and if it stays on, that size works.

I'm between two sizes — what do I pick?

KiWear uses whole US sizes only, so always round up. Paper and strip readings tend to run half to one size large, so trim a little. A ring should breathe and keep its sensors on your skin — favour a touch of room over a tight squeeze.

Does my finger type change the size?

A little. Wide knuckle with a slim base: size to clear the knuckle — a little play at the base is normal. Prone to swelling: size to your peak and round up. Slim fingers: measure relaxed so it won't spin and slip. Sweaty hands: dry off first, then pick a standard snug size.

What if it doesn't fit when it arrives?

The KiWear Sizing Kit — a full try-on set, US 6–15 — lets you lock your exact size before we make yours. Because sizing happens before fulfillment, a bad fit is rare — but if the size you confirmed still isn't right when it arrives, we'll exchange it.

The campaign is coming

Be first when KiWear Ring goes live.

Join the list for the Kickstarter launch and early-bird pricing. One small gesture to start — we'll handle the rest.