A buttonhole is a deliberate gap you knit into fabric, sized to fit your button

A buttonhole is a small opening you create while knitting by binding off stitches in one row and casting them back on in the next row. The gap lets a button pass through. You can make buttonholes in any knitted garment—cardigans, sweaters, baby clothes—and they're sized to match your specific button, not the other way around.

The most common method is the one-row buttonhole, which works for buttons up to about half an inch wide. For larger buttons, a two-row buttonhole gives you more fabric and a sturdier opening. Both methods are straightforward once you understand the sequence: bind off stitches, work across the gap, then cast the stitches back on in the row that follows.

Key Takeaways

  • Measure your button's diameter before you start knitting, then bind off that many stitches plus one extra to create the opening.
  • A one-row buttonhole works for small buttons and takes just two rows of knitting; a two-row buttonhole is sturdier and better for larger buttons.
  • Cast your stitches back on using the cable cast-on method so the new stitches match the tension of the rest of your fabric.
  • Test the buttonhole with your actual button before you finish the garment, because ripping back is easier than fixing a hole that's too small.

Measure your button before you knit

Take your button and measure straight across the widest part. Write down the measurement in inches or centimetres. Now count how many stitches equal that distance on your knitted fabric—this is your stitch gauge. If your gauge is 5 stitches per inch and your button is 0.6 inches wide, you need to bind off 3 stitches (0.6 × 5 = 3).

If you're unsure of your gauge, knit a small swatch in the same yarn and stitch pattern you're using for the garment, measure it, and count the stitches. This takes five minutes and prevents buttonholes that are too tight or too loose. Keep the swatch—you'll use it to test the button later.

One-row buttonhole: the most common method

Work your knitting until you reach the row where the buttonhole should sit. On that row, knit across until you're one stitch before the buttonhole position. Slip that stitch to your right needle without knitting it, then pass the yarn to the front of your work. This is called a yarn-over setup.

Now bind off the number of stitches your button needs. To bind off, knit the next stitch, then pass the slipped stitch over it. Knit another stitch and pass the previous stitch over it. Repeat until you've bound off all the stitches for your buttonhole. You should have one stitch left on your right needle and a gap in your fabric.

Finish that row normally. On the next row, when you reach the gap, use the cable cast-on method to add stitches back. Insert your needle under the loop between the last stitch on your left needle and the first stitch after the gap, pull yarn through, and place the new stitch on your left needle. Repeat until you've cast on the same number of stitches you bound off. The cable cast-on creates stitches that match the tension of your fabric better than other methods.

Two-row buttonhole: for larger buttons and durability

A two-row buttonhole uses two rows of knitting to create the opening, which makes it stronger and more visible. Work to the buttonhole position and bind off your stitches the same way as the one-row method. Finish that row, but do not cast the stitches back on yet.

On the next row, work across until you reach the gap. Cast the stitches back on using the cable cast-on, then continue across the row. The extra row of knitting creates a thicker edge around the opening, which is especially useful for buttons larger than half an inch or for garments that will get heavy use.

Casting stitches back on correctly

The cable cast-on is the best choice for buttonholes because it creates a neat, even edge that matches the rest of your fabric. Insert your right needle under the loop between the last stitch on your left needle and the gap, wrap yarn around the needle as if to knit, and pull the new loop through. Place this new stitch on your left needle. Repeat until all stitches are cast back on.

If you use a different cast-on method—long-tail or thumb cast-on, for example—the new stitches may look loose or uneven. The cable cast-on takes a few extra seconds but gives you a professional finish. Practice on scrap yarn first if you're not familiar with it.

Test the buttonhole before you finish

Once you've completed the buttonhole, thread your actual button through it while the garment is still on the needles. The button should slide through with slight resistance—not so tight that you have to force it, and not so loose that it falls through. If it's too small, you can rip back and redo the buttonhole with one more bound-off stitch. If it's too large, you can add a stitch or two when you cast back on.

Testing now saves you from finishing a garment only to discover the buttonholes don't fit. Keep testing each buttonhole as you knit them, especially if you're making several on the same garment.

Common mistakes and how to avoid them

The most frequent error is binding off too many stitches, which creates a hole that's too large. Measure carefully and count twice. Another common problem is casting the stitches back on too tightly, which makes the buttonhole pucker. Use the cable cast-on and keep your tension relaxed—the new stitches should sit at the same height as the surrounding fabric.

Some knitters forget to account for the extra stitch needed in the bind-off sequence. If your button is 3 stitches wide, bind off 4 stitches total (the 3 stitches plus 1 extra to complete the bind-off). This is straightforward to overlook, so write it down before you start the row.

Frequently Asked Questions

Can I make a buttonhole in a stitch pattern like ribbing or cables?

Yes, but plan ahead. Mark where the buttonhole should sit before you start the garment, and work the buttonhole in stockinette stitch (knit and purl rows) rather than in the pattern. This keeps the buttonhole neat and prevents the pattern from distorting around the opening. You can return to your stitch pattern above and below the buttonhole.

What if my buttonhole is too small after I finish?

If the buttonhole is only slightly too small, try gently stretching it with the button in place. If that doesn't work, you'll need to rip back to the buttonhole row, redo it with one more bound-off stitch, and reknit the rows above it. This is easier to do while the garment is still on needles than after you've cast off.

Do I need to reinforce the buttonhole edges?

For most garments, no. The cable cast-on creates a sturdy edge on its own. If you're making a heavily used garment or using a delicate yarn, you can sew around the buttonhole opening with matching thread after you finish knitting, using a whip stitch to find the edges. This is optional and mostly a matter of preference.

How many rows apart should buttonholes be?

Space them based on your button size and the garment's length. For a cardigan, buttonholes are usually 2 to 3 inches apart vertically. Measure your buttons and the garment, then divide the total length by the number of buttons you need. Mark the positions on your pattern before you start knitting so you don't have to count rows while you work.