General Formula for Garter Stitch Hat

I thought I would generalize the way I figured out the Garter Stitch Baby Hat, so that it can be adapted to other head sizes and other yarns and gauges.  I'm a bit of a math geek, but I hope this will make sense to everybody.   No guarantees!  I have tried it with a couple of sizes and kinds of yarn, but I can't try every possibility.

If it bothers you to work from a general formula like this, I suggest writing out the pattern for your particular hat in detail before you start (fairly easy if you cut-and-paste on a computer).

Numbers you need to know:

• C = desired circumference of hat
• L = desired length from center to edge of hat
• G = gauge (stitches per inch in garter)
• R = row gauge (rows per inch in garter)

Since the hat is knitted sideways, the row gauge is more important than with many patterns, so measure it carefully with a swatch several inches long.

Multiply the circumference by rows per inch to figure out how many rows you need to go around the hat.   Divide by 6 to get number of rows in each wedge.   Round to an even number.  Call this W, for wedge rows.  In other words:
        W = R*C/6 (rounded to even number)

Multiply the desired length by stitches per inch to get the number of stitches you need to cast on.  Round to an even number.  Call this S, for stitches.  In other words:
         S = L*G

In my pattern, C = 14", L = 6", G = 6.5 stitches/inch, R = 11 rows/inch.    So W=11*14/6, which is 25 point something and rounds to 26.  S = 6*6.5 = 39, which I rounded to 40.

The short row shaping is done over the stitches towards the top of the hat -- W/2 stitches, to be exact.  To make writing the pattern a little simpler, let's give that number its own name (T for "top"):
        T = W/2

Here's the general pattern:

Start by casting on S stitches with a provisional cast on.  
Rows 1-3: Knit all S stitches.
Row 4: Knit until there are T stitches left, then turn.
Row 5 and all remaining odd-numbered rows: knit back to starting edge
Row 6: Knit until there are T-1 stitches left, then turn
Row 8: Knit until there are T-2 stitches left, then turn
.... and so on until...
Row W-4: Knit until there are 2 stitches left, then turn
Row W-2: Knit until there is 1 stitch left, then turn
Row W: Knit all S stitches.

Now you should have a wedge-shaped piece of fabric. Repeat the rows above 5 more times so that you have a total of 6 wedges. Put the loops from your provisional cast-on onto a needle and graft them together with the stitches at the end of your last row (S stitches on each). 

If you don't want to use a provisional cast-on or Kitchener Stitch, you can do a regular cast-on and cast-off and just seam the start and end together. If you do this, I'd omit the rows 1 and 2 on the first wedge to make up for the width of the cast-on and cast-off.  I haven't tried this.

Whichever way you join the side, there will be a little hole left on top. Run a length of yarn around the edges of the hole twice, then pull tight.  Work in all the ends, turn up the cuff, and you're done!

Garter Stitch Baby Hat

I recently made a Baby Surprise Jacket for a friend who is expecting her first baby. For a hat to go with it, I thought of an adult-sized garter stitch pattern that I've used and like a lot: Judy Gibson's Braid-Edged Cap, which you can find on Ravelry. I adapted her short row hat construction to the smaller size and different weight of yarn and am posting this pattern with Judy's permission. I left off the braid to make a simpler hat that would coordinate better with the garter stitch jacket. I'm sure a baby hat with a braid would be cute too, but that's a project for another day....

Disclaimer: I don't think of myself as a designer and this is the first pattern I've ever posted. These are the notes I took while creating the hat. It has not been test knit. If you try it and find an error, please let me know about it. If you try it and it works for you, please let me know.

This hat is sized for a newborn, about 14" in circumference. I made it 6" long, so I could fold up a cuff.  If you don't want the cuff you could use 10-12 fewer stitches. But I like using a cuff for a stretchy hat like this because it may mean the baby can wear it longer as it grows.

Yarn: sport weight. I used Knit Picks Felici Sport, a self-striping yarn that has sadly been discontinued. It took 25 grams.
Gauge: 13 stitches to 2 inches.
Needles: I used 2.75 mm (U.S. size 2) to get the gauge.  (But be warned that I'm a loose knitter!)

Cast on 40 stitches using a provisional cast on.
Rows 1-3 and all odd rows: Knit all 40 stitches.
Row 4: Knit 29 and turn (leaving 11 stitches unworked)
Row 6: Knit 30 and turn (leaving 10 stitches unworked)
Row 8: Knit 31 and turn (leaving 9 stitches unworked)
Row 10: Knit 32 and turn (leaving 8 stitches unworked)
Row 12: Knit 33 and turn (leaving 7 stitches unworked)
Row 14: Knit 34 and turn (leaving 6 stitches unworked)
Row 16: Knit 35 and turn (leaving 5 stitches unworked)
Row 17: Knit 36 and turn (leaving 4 stitches unworked)
Row 20: Knit 37 and turn (leaving 3 stitches unworked)
Row 22: Knit 38 and turn (leaving 2 stitches unworked)
Row 24: Knit 39 and turn (leaving 1 stitches unworked)
Row 26: Knit all 40 stitches.

Now you should have a wedge-shaped piece of fabric. Repeat the 26 rows above 5 more times so that you have a total of 6 wedges. Put the loops from your provisional cast-on onto a needle and graft them together with the 40 stitches at the end of your last row.

If you don't want to use a provisional cast-on or Kitchener Stitch, you can do a regular cast-on and castoff and just seam the start and end together. If you do this, I'd omit the rows 1 and 2 on the first wedge to make up for the width of the cast-on and cast-off.

Whichever way you join the side, there will be a little hole left on top. Run a length of yarn around the
edges of the hole twice, then pull tight.  Work in all the ends, turn up the cuff, and you're done!