📿 Beading Project Quantity Calculator
Enter your desired finished strand length and the diameter of your beads to see how many beads you'll need.
How the bead count is worked out
Beads are assumed to sit touching, so each one takes up its own diameter along the strand and the count is the length divided by that, rounded down:
beads = floor(strand length mm / bead diameter mm)The defaults give floor(450 / 6) = 75 beads. Rounding down means the strand finishes at or just under the length asked for: at 7 mm the same 450 mm gives floor(64.28) = 64 beads, which strings to 448 mm, 2 mm short. Both fields are millimetres, and an inch is 25.4 mm - a 16 in strand is 406.4 mm and holds 67 beads of 6 mm.
Adjusting the length before you divide
- Take the clasp off the length first. A lobster clasp with its jump ring and tag adds 12 to 20 mm. For a finished 450 mm necklace with a 15 mm clasp, enter 435 and you get 72 beads.
- Mixed sizes: divide by the repeat. Alternating a 6 mm round with a 3 mm spacer makes a 9 mm unit; enter 9 to get 50 units, which is 50 of each bead.
- Nominal sizes lie. Gemstone rounds routinely run 0.3 mm over or under. Across 75 beads that is 22 mm, so string against a ruler rather than trusting the count.
- Seed beads are sized by aught. An 11/0 is about 1.8 mm wide, so a 450 mm rope takes 250 of them.
Frequently asked questions
How many 6 mm beads are in an 18 inch necklace?
18 in is 457 mm, which divides into 76 beads. Allow for the clasp: subtract its length first and you are nearer 73.
How many 8 mm beads are on a 16 inch strand?
406.4 mm divided by 8 is 50. That is why bulk gemstone strands are usually described as about 50 beads for 8 mm and about 67 for 6 mm.
Do I need extra beads beyond the calculated number?
Buy 10 per cent more. Beads chip when crimped, sizes vary within a strand, and matching a dye or a stone lot later is often impossible.