Estimate Tail Length for Cast On

The big question when working a Long Tail Cast On is how long should that tail be? It’s really frustrating to run out of yarn before the cast on is complete. There are a number of ways to estimate the length of the tail.

Use Math

Multiply your finished measurement by pi (3.14), then add about 6” / 15 cm for the tail. I usually round up and end up multiplying by 4.

i.e. 20” wide sweater needs an 86” tail

20 x 4 = 80 + 6 = 86”

Pre-Measured Tail

Ten stitches cast onto needle. Cast on 10 or 20 sts.

Ten cast-on stitches being slipped off needle while pinching tail at base of stitches and holding first stitch on needle. Securing both ends of the tail (first stitch and last stitch), slide stitches off the needle.

Unraveled length of yarn representing the tail length required for ten cast-on stitches. Unravel stitches while holding onto both ends of tail used to make the stitches.

Length of yarn measured out by measuring out an initial length and folding extra yarn back and forth four times. Use that pre-measured tail length to calculate your full cast on. In this case, four times the measured amount of the initial 10 stitches will be enough for 40 stitches.

Quick Hack for Pre-Measured Tail

Yarn wound around a needle ten times. Loosely wrap the yarn around your needle 10 or 20 times, unwind it and use that measurement to calculate a longer cast on.

Two Balls

Several stitches cast onto needle started with a slip knot holding two strands together; orange used for tail and pink used for stitches. Working from two separate balls of yarn or the inside and outside of a ball, join two ends together with a slip knot and work the cast on from the join. Don’t include the slip knot when counting cast-on stitches. When you’re done, remove the slip knot and cut one of the ends. The drawback with this method is that there are two additional ends to weave in.