Tandon Gems

How many 2, 3 and 4 mm rondelles or heishi for ring sizes 5 to 10

Tara Tandon, Tandon GemsPublished January 21, 2026· Reviewed September 7, 2026· 2 min read

This article is a reference guide. Confirm the current strand, price and quantity with Anish before ordering.

Short answer

Divide the ring inner circumference by bead outside diameter to get count. For US sizes, approximate counts: size 5 about 25 of 2 mm, 16 of 3 mm, or 12 of 4 mm; size 7 about 27, 18, or 14; size 9 about 29, 20, or 15; size 10 about 29, 20, or 16. See the full table.

In short

  • Formula: inner circumference times pi divided by bead OD, then round.
  • Round to the nearest whole bead, then test on the finger.
  • Size 7: about 27 of 2 mm, 18 of 3 mm, or 14 of 4 mm beads.
  • A 16 inch strand makes about 7 size 7 rings in 2 to 4 mm.
  • Knotting between beads adds about 1 mm per knot and changes counts.

How many beads make sizes 5 to 10?

Use these counts for US sizes 5 to 10 with 2, 3 and 4 mm rondelles or heishi on stretch.

Below are approximate whole-bead counts. Round as needed for comfort.

  • Size 5: 2 mm 25, 3 mm 16, 4 mm 12
  • Size 6: 2 mm 25, 3 mm 17, 4 mm 13
  • Size 7: 2 mm 27, 3 mm 18, 4 mm 14
  • Size 8: 2 mm 29, 3 mm 19, 4 mm 14
  • Size 9: 2 mm 29, 3 mm 20, 4 mm 15
  • Size 10: 2 mm 29, 3 mm 20, 4 mm 16

How do you calculate bead counts for a ring?

We use standard ring size diameters, multiply by pi to get inner circumference, then divide by bead outside diameter. That yields the count.

The ring-blank approach is diameter times pi. Round to a whole bead.

If you prefer to confirm fit, wrap a narrow paper strip to the desired size, mark the overlap, measure the length, then divide by bead size.

Should you round up or down?

Round to the nearest whole bead first. Then judge comfort on the finger under normal wear.

On elastic, a slightly lower count often feels right once the knot is set. On non-stretch thread, match the math more closely and adjust by a bead if needed.

What bead shapes work best for tiny rings?

Both rondelles and heishi size cleanly because counts are based on outside diameter. Thickness or height mostly changes the ring's profile.

Micro faceted rondelles give sparkle and flex nicely. Heishi read as a sleek column and stack well with metal accents.

What should you string with and how do you finish?

Use a fine elastic or strong beading thread that passes comfortably through your bead holes twice for a secure knot. Keep the knot small and tuck inside a bead if possible.

Tara here: we set the knot with a tiny dot of clear adhesive and let it cure before trimming, so it does not creep under tension.

How many rings can a strand make?

On a 16 inch strand, the typical bead counts are about 200 of 2 mm, 133 of 3 mm, and 100 of 4 mm. For a size 7 ring, that is about seven rings per strand across these sizes.

Our Jaipur-cut micro strands in sapphire and tourmaline are popular for ring stacks. See stone overviews: sapphire and tourmaline. Come try them at our shows.

Common questions

Do rondelles and heishi change the count for the same millimeter size?

If both are measured by outside diameter, the count is the same. Shape mostly changes the ring's profile and feel.

Can I mix 2 and 3 mm beads in one ring?

Yes. Average the outside diameters for a quick estimate, or string a test ring and adjust by a bead for fit before committing your final knot.

How do I handle half sizes like 5.5 or 7.5?

Measure the inner circumference for that size, divide by bead size, and round to a whole bead. Then test on the finger and nudge by one bead if needed.

Will tiny spacers between beads change the count?

Yes. Any spacer adds length, so you may drop a bead from the base count. Build a test and check fit before trimming your tails.

How do I convert non-US sizes to use this method?

Look up the ring's inner diameter in millimeters on a standard chart, multiply by pi to get circumference, then divide by bead size and round.

Sources and checks

  1. Ring Size Charts, Conversions, and Sizing it Right the 1st time - Ganoksin Jewelry Making Community
  2. Calculating ring blank length - Jewelry Discussion - Ganoksin Orchid Jewelry Forum Community for Jewelers and Metalsmith
  3. Bead and Necklace Size Charts - International Gem Society

Catalog details are reference information. Ask Anish to confirm the current strand, price and availability.

Want a strand like the ones in this post?

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