Plain Mittens from Scratch

This pattern was born out of my desire to help a cause and is written specifically for knitting in the round using two circular needles. A tutorial for that technique can be found here.

Materials:

Yarn of your choice (superwash worsted used in photos.)

Two circular needles, preferably of the same length, in a size which will produce a firm but supple fabric from your yarn (5 stitches per inch in photos.)

Two circular needles in a smaller size for ribbing: usually two or three sizes down.

Yarn needle and scissors.

Terminology:

M1 = make one stitch using the method of picking up the horizontal strand between two stitches, twisting it and knitting through it as seen here.

LLDec = left-leaning decrease.  This will vary depending on how your stitches are mounted.  For me knitting in the round, this would be K2Tog.

RLDec = right-leaning decrease.  This will also vary depending on how your stitches are mounted; when in the round mine is slip-slip-knit-together.

This is a formula-based pattern where X is any integer you like; in the pair I made X = 8 which made mittens for a small adult or large child hand. Numbers for the sample pair are in brackets. Varying X and yarn/needles should give a range of sizes.

Pattern:

With larger needles using two-tail method over both needles (to add elasticity) cast on 4X [32].

Slide one circular needle out entirely and use it to purl back across the cast-on row (flat knitting.) Turn the work.

Make it into round work with the join centered on what will be the palm-side needle as follows:
Knit X [8] with separate needle, center stitches on that needle and drop it.
Knit 2X [16] using left end of holding needle brought around to  your right hand. Center the stitches and drop that needle then bring up the first needle with the X [8] stitches already on it and knit the last X [8] stitches.

Knit ONE round of K1, P1 ribbing on the larger needles then switch to smaller needles.
Do (2X - 1) [15] more rounds of ribbing for a total of 2X  [16] rounds.

Switch back to larger needles, K X [8] rounds plain.

On next (X+1)  [9th] plain round start thumb gusset:

For right hand:   Knit 3X + 1 [25] stitches: this should be the beginning of the round still on the palm-side needle, all the stitches from the back needle and one stitch from the other end of the palm-side needle.  M1 from the horizontal bar after that 1st stitch. Knit the rest (X - 1) [7] of the stitches for that round.

For left hand: Knit X - 1 [7] stitches: this should be all but one of the palm-side stitches at the beginning of the round. M1 from the horizontal bar in front of that last stitch. Knit the rest (3X + 1) [25] of the stitches for that round.

Knit 1 round plain.

Continue thumb gusset by increasing 1 stitch on each side of the gusset (2 per row) alternating with one round of plain (no increases) knitting X  [8] times.

Example using right hand mitten:
Knit 1, increase, Knit 1, increase, knit around -- knit one plain round.
Knit 1, increase, Knit 3, increase, knit around -- knit one plain round.
Knit 1, increase, Knit 5, increase, knit around -- knit one plain round. Etc.

This will give a thumb gusset of 2X-1 [15] stitches ending with a plain (no increases) round.

On next round, knit to the thumb gusset stitches and put them on waste yarn or holder. Cast on 2 stitches using backward loop and finish the round:  4X plus 2 [34] stitches.

Knit one plain round incorporating the newly made stitches.

On next round get rid of the two newly made stitches by RLDec with stitch ahead of gusset and LLDec with stitch after the gusset. Now back to 4X [32] stitches, 2X [16] on each needle.

(This add-in-subtract-out allows for mobility at the thumb joint and helps prevent wear/gapping.)

Knit 2X [16] plain rounds after the above decrease round.

Begin finger decreases:
Knit to last 3 stitches on palm-side needle, LLDec, K1. 
Knit 1 stitch of back-side needle, RLDec, knit to last 3 stitches on that needle, LLDec, K1.
Knit 1, RLDec, knit to end of round (in center of palm.)

Knit 1 round plain.  Continue in this manner alternating a decrease round with a plain round till 4 stitches are left on each needle.   Break yarn leaving a generous tail but do not remove needles.

Turn mitten inside-out while still on the needles (feeding the circulars through the hole--this is why double-points won't work unless you transfer the live stitches to safety pins, turn work and then re-insert double-points)

Do 3-needle bind-off from the wrong (purl, inside) side of work. Turn.

Thumb:

With one circular needle, pick up a stitch from the base of one backward-loop cast-on stitch -- go through two strands of yarn so it won't gap.  Knit half plus one or half minus one (the thumb gusset is an odd number of stitches, recall) of the held stitches. Center stitches on needle and drop it.
With other circular needle, knit the remaining held stitches and then pick up a stitch from the base of the other cast-on stitch. Now have 2X +1 [17] stitches in thumb.

Knit one round plain.

LLDec, knit to last 2 stitches of round, RLDec.  Now have 2X - 1 stitches [15] again.

Knit X [8] rounds plain.

Next round spread X/2  (rounding to nearest even whole number) [4] decreases across the round.

Knit 1 round plain.

Knit 1, Knit 2 together all across next round.

Knit 1 round plain. Break yarn, pull through stitches.

Weave in all ends.