3D Printable Ring Generator (STL by Ring Size)
Pick your ring size in US, UK, EU or Japanese sizes, or type the inner diameter. Choose a comfort-fit, flat, D-shape, court or faceted band, set the width and thickness, and add text outside or inside. Preview it in gold, silver, rose gold or black, then download a printable STL or 3MF.
How to make a 3D printed ring in your size
- 1
Pick your size
Choose US / Canada, UK / Australia letters, EU or Japanese sizes, or type the inner diameter in mm. No size? Measure around your finger with a strip of paper.
- 2
Shape the band
Comfort fit, flat, D-shape, court or faceted, with the width, thickness and an edge chamfer. The inside diameter stays exactly your size.
- 3
Add text
A name, a date or a word, engraved or raised on the outside, or engraved on the inside so it reads when you look into the ring.
- 4
Print a test ring
Download the STL or 3MF and print a quick test ring in PLA first. Adjust the tolerance if it is tight or loose, then print it in resin or send it for casting.
Ring size chart
Inner diameter and circumference for US / Canada sizes 3-13, with the nearest UK / Australia letter, EU / ISO size and Japanese size. Computed from the ISO 8653, BS 6820 and Japanese size formulas; ≈ means the nearest size in that system.
| US / CA | Inner diameter | Circumference | UK / AU | EU | JP |
|---|---|---|---|---|---|
| 3 | 14.07 mm | 44.2 mm | ≈ F½ | ≈ 44 | ≈ 4 |
| 3.5 | 14.47 mm | 45.5 mm | ≈ G½ | ≈ 45.5 | ≈ 5 |
| 4 | 14.88 mm | 46.8 mm | ≈ H½ | ≈ 47 | ≈ 7 |
| 4.5 | 15.29 mm | 48.0 mm | ≈ I½ | ≈ 48 | ≈ 8 |
| 5 | 15.69 mm | 49.3 mm | ≈ J½ | ≈ 49.5 | ≈ 9 |
| 5.5 | 16.10 mm | 50.6 mm | ≈ K½ | ≈ 50.5 | ≈ 10 |
| 6 | 16.51 mm | 51.9 mm | ≈ L½ | ≈ 52 | ≈ 12 |
| 6.5 | 16.91 mm | 53.1 mm | ≈ M½ | ≈ 53 | ≈ 13 |
| 7 | 17.32 mm | 54.4 mm | ≈ N½ | ≈ 54.5 | ≈ 14 |
| 7.5 | 17.73 mm | 55.7 mm | ≈ O½ | ≈ 55.5 | ≈ 15 |
| 8 | 18.13 mm | 57.0 mm | ≈ P½ | ≈ 57 | ≈ 16 |
| 8.5 | 18.54 mm | 58.2 mm | ≈ Q½ | ≈ 58 | ≈ 18 |
| 9 | 18.95 mm | 59.5 mm | ≈ R½ | ≈ 59.5 | ≈ 19 |
| 9.5 | 19.35 mm | 60.8 mm | ≈ S½ | ≈ 61 | ≈ 20 |
| 10 | 19.76 mm | 62.1 mm | ≈ T½ | ≈ 62 | ≈ 21 |
| 10.5 | 20.16 mm | 63.3 mm | ≈ U½ | ≈ 63.5 | ≈ 22 |
| 11 | 20.57 mm | 64.6 mm | ≈ V½ | ≈ 64.5 | ≈ 24 |
| 11.5 | 20.98 mm | 65.9 mm | ≈ W½ | ≈ 66 | ≈ 25 |
| 12 | 21.38 mm | 67.2 mm | ≈ X½ | ≈ 67 | ≈ 26 |
| 12.5 | 21.79 mm | 68.5 mm | ≈ Z | ≈ 68.5 | ≈ 27 |
| 13 | 22.20 mm | 69.7 mm | ≈ Z½ | ≈ 69.5 | ≈ 29 |
The settings
| Ring size | US / Canada 1-16 in quarter sizes, UK / Australia A-Z½, EU / ISO 40-76 (the inner circumference in mm), Japan 1-30, or any inner diameter from 10 to 30 mm. Every system is shown side by side for the size you pick. |
|---|---|
| Tolerance | Added to the inner diameter, from -1 to +1 mm (0 by default). Printers often make holes a little small: if your test ring is tight, add 0.1-0.3 mm and print again. |
| Band profile | Comfort fit (domed inside, flat outside), flat, D-shape (flat inside, domed outside), court (domed on both sides) or faceted (5-24 flat sides outside). The size is always the narrowest inner diameter. |
| Width and thickness | Width 1.5-25 mm along the finger, thickness 0.5-5 mm (the thickest wall, at mid-width). Thinner than 0.8 mm gets a warning. |
| Edge chamfer | A 45° cut on the square edges, 0-2 mm (0.3 mm by default), so the ring is softer to wear and the first layer does not flare. |
| Text | Outside engraved, outside raised, or inside engraved, with the letter height, depth and spacing. The tool checks that the text fits around the ring and leaves at least 0.4 mm of wall under an engraving. |
| Metal preview | Gold, silver, rose gold or black in the 3D view, for the look only. The file is plain geometry: the colour comes from your filament, resin or metal. |
How to print it: test ring, resin or metal
Test fit: FDM in PLA
Print a test ring in PLA first: sizes vary with print shrink and with how each printer makes holes. It takes minutes and a few grams of filament. Use it to set the tolerance before the real print.
Detail: resin
For fine text and a smooth finish, print on a resin (SLA / MSLA) printer. Wash and cure it fully, and check that your resin is rated for skin contact before you wear it.
Metal: casting
For silver or gold, take the STL to a jeweller or a casting service. They print it in wax or a castable resin and cast it by lost-wax casting. Ask them how much to scale up for their metal shrink.
Rules of thumb behind the sizes and warnings
| Check | Rule of thumb | Source |
|---|---|---|
| Ring size | A ring size is the inside of the band: US / Canada add 0.032 in (0.8128 mm) of diameter per size, EU / ISO sizes are the inner circumference in mm, UK / Australia letters add 1.25 mm of circumference per letter, Japan adds 1/3 mm of diameter per size. | ISO 8653 and BS 6820 tables as summarised on Wikipedia "Ring size"; horsekeeping.com and antiquejewel.com size charts |
| Comfort fit | A domed inside slides over the knuckle more easily, so it is sized at its narrowest point. This tool measures every profile there. | Jewellery forums such as Ganoksin on sizing comfort-fit bands |
| Casting shrink | Metal shrinks as a casting cools, and casters often scale the model up by a small percentage that depends on the alloy and their process. Ask your caster for their number and scale the STL by it. | Ganoksin and 3D printing community forum threads on casting shrinkage |
| Test ring first | Printed ring sizers come in a range of sizes because printers differ; if a test ring prints tight, scale it or add tolerance. | Ring sizer STL sets on 3D model sites |
| Thin bands | Below about 0.8 mm a printed band bends or cracks easily, so the tool warns. An engraving always leaves at least 0.4 mm of wall. | The3DAI defaults (rules of thumb, not a standard) |
Rules of thumb, not guarantees: every printer, resin and caster differs. Sites named on this page are named only to describe compatibility or as sources; The3DAI is not affiliated with or endorsed by them.
Want a custom pendant or charm instead? Describe it and get a 3D model with AI
A heart pendant, a little animal charm, a letter or a keepsake: type what you want and get a printable 3D model, or turn a photo into one. The AI generators use credits; this ring generator does not.