Bead size chart (mm & actual size)
Compare bead sizes at true physical size, convert millimeters to inches, and calculate how many beads you need. Round sizes use Fire Mountain Gems strand counts; seed beads use published aught-to-mm standards. Sizes are approximate and vary by brand.
All bead sizes at actual size
Calibrate to your screen with a credit card (or use the print view) so every bead below is physically accurate.
Printed at 100% scale, the marks below should measure exactly: the gold line = 1 inch, the "50" tick = 50 mm. If not, set your print scale to 100% (not "fit to page").
Bead size chart
| Size | Diameter | Per inch | Per 16″ strand | Details |
|---|---|---|---|---|
| 2 mm | 0.079″ | 12.7 | 203 | — |
| 3 mm | 0.118″ | 8.5 | 136 | — |
| 4 mm | 0.157″ | 6.3 | 100 | 4 mm page |
| 6 mm | 0.236″ | 4.2 | 67 | 6 mm page |
| 8 mm | 0.315″ | 3.2 | 50 | 8 mm page |
| 10 mm | 0.394″ | 2.5 | 41 | 10 mm page |
| 12 mm | 0.472″ | 2.1 | 34 | — |
| 6/0 | 4–4.3 mm | 6–6 | seed bead | Seed beads |
| 8/0 | 2.5–3.1 mm | 8–10 | seed bead | Seed beads |
| 10/0 | 2–2.3 mm | 11–13 | seed bead | Seed beads |
| 11/0 | 1.8–2.1 mm | 12–14 | seed bead | Seed beads |
| 15/0 | 1.3–1.4 mm | 18–20 | seed bead | Seed beads |
Per-inch counts use the exact rule 25.4 ÷ diameter(mm). Seed-bead "per inch" is a range because seed sizes vary by brand.
Beads-per-strand calculator
Sources, calibration & how the counts are computed
On-screen sizes are only accurate after you calibrate your display to a real credit/debit card (ISO/IEC 7810 ID-1 = 85.60 mm wide). Before you calibrate, beads are shown NOT to scale. For a guaranteed-accurate size, use the print view at 100% with the printed ruler.
Beads per inch and beads per strand use the standard estimate beads = round(length_in x 25.4 / diameter_mm), where 1 inch = 25.4 mm. Counts are approximate; actual bead lots vary.
Data basis: Round 16-inch-strand counts from Fire Mountain Gems (equal to the 25.4/mm-per-inch invariant); seed-bead mm ranges from the Wikipedia seed-bead standards table with Miyuki/Toho/Czech notes.
Last reviewed 2026-06-18.
General jewelry-making reference. Bead dimensions are approximate and vary by manufacturer, material, and finish; measure your own beads with calipers when precision matters.