🌀 Wire Wrapping Length Calculator
Enter the number of wraps and the diameter of what you're wrapping around (a ring mandrel, bead, or stone) to see the total wire length needed, including a tail allowance.
How the length is worked out
Every wrap is one circumference of the thing you are wrapping, and the tail is added once at the end:
wraps length = wraps × π × diameter
total = wraps length + tail allowance
inches = total / 25.4The defaults - 5 wraps round 10 mm with a 50 mm tail - give 5 × π × 10 = 157 mm of wrapping plus 50, so 207 mm, or 8.2 in. On a size 7 ring mandrel, 17.3 mm, the same five wraps take 272 mm.
Correcting for the wire itself
The wrap does not sit on the core, it sits on top of it, so the true path is π × (core + wire diameter). Wrapping 20 AWG at 0.812 mm around that 10 mm core is really π × 10.812 = 34 mm a turn, 170 mm over five wraps rather than 157 - about 8 per cent short. Enter the core plus one wire diameter, and two more per layer if the coil stacks.
- The tail covers both ends. 50 mm grips one end with flat-nose pliers; add 25 to 30 mm for a wrapped loop.
- Jump rings are the same sum. Each ring off a mandrel costs π × (mandrel + wire), so 50 rings on a 5 mm mandrel in 18 AWG take about 945 mm of wire.
Frequently asked questions
How much wire do I need to wrap a stone?
Take the girth at the widest point and multiply by the number of passes, then add 50 to 100 mm of tail. A 30 mm cabochon has a 94 mm girth, so four passes come to about 430 mm.
How do I calculate wire for jump rings?
π × (mandrel diameter + wire diameter) per ring. On a 5 mm mandrel in 18 AWG that is 18.9 mm each, so a metre of wire yields about 52 rings.
Why does my wire run out before the last wrap?
Usually because the core diameter was entered without the wire thickness. On a 10 mm core in 20 AWG that alone loses 8 per cent of the length.