What a float is and why you need to catch it
A float is a strand of yarn that runs across the back of your knitting without being anchored to a stitch. It happens most often in colorwork — when you carry one color across several stitches while working another color — but it can also appear when you skip stitches or work loose tension. The float sits loose on the back of the fabric.
Floats matter because they catch on things. A loose strand on the back of a sweater will snag on a finger, a ring, or a button when you pull the garment on or off. Once snagged, the float pulls tight and can pucker the fabric or even unravel nearby stitches. Catching floats — anchoring them to the stitches underneath — prevents this damage and keeps the fabric stable.
The longer the float, the more likely it is to snag. Most knitters catch floats that span more than three or four stitches, though some catch every float depending on the yarn weight and how the garment will be worn.
Key Takeaways
- A float is a loose strand of yarn on the back of your knitting that can snag and damage the fabric if left uncaught.
- The most common method is to trap the float under a stitch as you knit, by picking it up and working it into the next stitch.
- You can catch floats as you work (in the moment) or go back and weave them in after the piece is finished.
- Floats longer than three or four stitches should almost always be caught to prevent snagging and puckering.
- Practice on a swatch first so you can see how the tension changes when you trap a float.
Catching floats while you knit
The fastest way to deal with floats is to catch them as you work. This method, sometimes called trapping, anchors the float to a stitch without breaking the yarn or adding extra steps later.
To trap a float on a knit stitch: work to the point where the float begins. Pick up the float with your working yarn and knit the next stitch, bringing both the working yarn and the float through the loop together. The stitch now holds the float in place. On the next stitch, drop the float and continue with only your working yarn. The trapped float sits inside the stitch on the back of the fabric.
To trap a float on a purl stitch: use the same method — pick up the float and purl the next stitch with both strands. The mechanics are identical; only the stitch type changes.
The key is to trap the float only once every three or four stitches, not on every stitch. Trapping too often creates bumps on the back and can make the fabric stiff. Space your traps so the float has room to sit loose between them without becoming long enough to snag.
Weaving floats in after you finish
If you did not catch floats while knitting, you can weave them in after the piece is complete. This method works well if you missed a float or prefer to handle colorwork without managing floats as you go.
Thread a tapestry needle with a length of yarn that matches the float color. From the back of the fabric, slide the needle under the float and over the next stitch, then under the float again and under the next stitch. Alternate this over-under pattern along the length of the float. The float becomes anchored to the stitches without showing on the front.
Weave each float in a slightly different path so the anchoring stitches do not stack on top of each other and create a visible line. Work slowly and keep tension loose — pulling too tight will pucker the fabric. When you reach the end of the float, weave the needle through a few nearby stitches to find the yarn, then trim the tail.
Tension and float length: what to expect
Floats that are too tight will pull the fabric inward and create visible dimples on the front. Floats that are too loose will hang and snag. The goal is a float that sits flat against the back without tension.
To judge the right length: hold the fabric so you can see the back. The float should lie flat and relaxed, with no slack but no pull. If you are working colorwork and switching colors frequently, your floats will naturally be shorter and easier to manage. If you carry a color across many stitches before using it again, that float will be longer and will need to be caught more often.
Practice on a small swatch using two colors. Work a few rows, deliberately leaving floats of different lengths, and see which ones snag and which ones sit flat. This teaches you the feel of the right tension before you commit yarn and time to a full project.
Common mistakes when catching floats
Catching floats too often — on every stitch or every other stitch — creates a bumpy, stiff fabric. The back of the piece will show a line of trapped floats, and the front may pucker. Catch floats only when they reach three to four stitches long.
Pulling the float too tight when you trap it will distort the stitches and create visible dimples. Keep the tension the same as your regular knitting. If you notice the fabric tightening, you are pulling too hard.
Forgetting to catch floats in colorwork until the piece is finished means you have to go back and weave them all in by hand. This is slower than catching as you go, though it does give you the option to skip floats that are short enough to be safe.
Mixing float colors — trapping a red float with blue yarn, for example — will show on the back. Always use yarn that matches the float color so the anchor stitches blend in.
When you do not need to catch floats
Short floats — those that span only one or two stitches — rarely snag and do not need to be caught. The stitches on either side of the float hold it in place naturally.
Floats on the inside of a garment, such as the inside of a hat or the inside of a sleeve, are less likely to snag because they do not rub against skin or clothing. You can often leave these uncaught if they are not too long.
Floats in a project that will not be worn — a blanket, a wall hanging, or a decorative piece — are lower risk. If the piece will sit on a shelf or hang on a wall, a snag is less likely than on a sweater you wear regularly.
Tools and materials you need
To catch floats while knitting, you need only your knitting needles and yarn. No extra tools are required. The float is managed as part of your regular stitching.
To weave floats in after finishing, you will need a tapestry needle (also called a yarn needle) with an eye large enough for your yarn. The needle should be blunt, not sharp, so it slides between stitches without splitting the yarn. You also need scissors to trim the tails.
Some knitters use a crochet hook to catch floats, especially in tight colorwork. The hook picks up the float and pulls it through a stitch loop. This is faster for some people but requires practice to keep tension even.
Frequently Asked Questions
How long can a float be before it will definitely snag?
Floats longer than four or five stitches are at high risk of snagging, especially on garments that are worn regularly. Floats of three stitches or fewer usually stay in place. The exact threshold depends on your yarn weight and how the garment will be used — a delicate lace shawl is less likely to snag than a sturdy sweater.
Can I catch floats on the front of the fabric instead of the back?
No. Catching floats on the front will show as visible bumps or lines and will ruin the appearance of colorwork. Always catch floats on the back side of the fabric, where they are hidden.
What happens if I trap a float too tightly?
Pulling too tight when you trap a float will pucker the fabric and create visible dimples on the front. The stitches around the trapped float will tighten and distort. Keep your tension the same as your regular knitting — the float should be anchored but not squeezed.
Do I need to catch floats in single-color knitting?
Floats in single-color knitting usually happen when you skip stitches or work very loose tension. If you have a float, catch it the same way you would in colorwork. Most single-color projects do not have floats unless you are working a textured stitch that deliberately skips stitches.
Is it faster to catch floats as I knit or weave them in later?
Catching floats as you knit is usually faster overall because you do not have to go back and weave them in by hand. However, some knitters find it easier to focus on colorwork without managing floats at the same time, so they weave in after finishing. Try both methods on a swatch and see which feels more natural to you.