How to Join Separate Front and Back Knitted Panels with Underarm Cast-Ons

First, locate the body-joining instruction for your size. Record the front stitch count, back stitch count and number of stitches to cast on at each underarm. Complete any armhole shaping required before that instruction. Underarm cast-ons belong between the panels, so identify both panel edges before moving stitches.

Keep the pattern’s construction in view. For example, Purl Soho’s Classic Knit Jacket works the back and fronts separately to the bottom of the armholes, then joins them with underarm cast-ons before continuing the body in one piece. Its open-front construction has a different working path from the circular pullover described here. Classic Knit Jacket construction notes.

Have your working circular needle, stitch holders or waste yarn, and the required markers ready. For ordinary circular knitting, choose a needle length that allows the stitches to reach around comfortably; a cable that is too long requires a suitable method such as magic loop. Ysolda’s guide to knitting in the round explains needle-length selection.

Lay out the garment with its right side facing outward and identify the next panel to be worked. Keep the fabric hanging consistently beneath the needle rather than wrapped around the cable. Before closing the circle, trace the fabric around both panels to check for a twist. This applies the same orientation check used when joining a new circular project. Ysolda’s circular-knitting tutorial.

If the back stitches are on waste yarn, transfer them to the working needle without changing their order. In her Inverleith tutorial, Ysolda places the held back stitches onto the needle at the end opposite the working yarn before beginning the join. That puts the back within reach after the first underarm cast-on. Inverleith preparation and joining instructions.

As a practical check, write the route on a small note: front → underarm A → back → underarm B → front. If your pattern begins elsewhere, rotate this sequence to match. The note should describe the actual order you will knit, including any stitches worked before reaching the first underarm.

Use the specified cast-on when the pattern names one. When it leaves the choice open, a knitted-on cast-on is one documented option. La Visch Designs demonstrates its use at the underarm and also explains the backward-loop alternative. The tutorial notes that backward loops can be difficult to work on the following round and may stretch at the connections. Casting on at the underarm for garments.

For the knitted-on method, the important distinction is where the needle enters: work into the newest stitch. Insert the right needle as though to knit, wrap the working yarn, draw a loop through, and place that new loop onto the left needle while retaining the original stitch. Repeat into the newest stitch until you have added the required number. La Visch Designs’ knitted-on cast-on tutorial.

Count only the added loops as underarm stitches. For instance, if the last panel stitch is already on the needle and you need six underarm stitches, make six new loops. The existing panel stitch remains part of its panel count.

The following procedure assumes your pattern begins by working a right-side pass across the front, then joins the back. Its turn–cast-on–turn action follows La Visch Designs’ underarm demonstration. Knitted-on underarm instructions.

1. Work across the front. Follow the established stitch pattern to its underarm edge.
2. Turn temporarily. With the wrong side facing, hold the needle carrying the working yarn in your left hand.
3. Cast on the first bridge. Add the specified number of stitches using the knitted-on method.
4. Turn back. Return to the right-side-facing position. The new stitches are now on the right needle.
5. Work across the back. Use the same working yarn to knit the waiting back stitches. Do not work back across the new cast-on stitches during this transition.
6. Make the second bridge. At the other edge of the back, repeat the temporary turn, cast-on and return.
7. Close the circuit. Check the fabric’s orientation, then continue into the front stitches as directed by your pattern.

The temporary turns let you form each cast-on; after turning back, continue onto the next panel. Place side markers and the beginning-of-round marker exactly where your pattern specifies. A marker within an underarm bridge and a marker at its edge represent different locations, so preserve that distinction when following later shaping instructions.

Here is an illustrative example, not a garment pattern: assume the front has 80 stitches, the back has 84 stitches, and each underarm requires 6 new stitches. Assume there are no increases or decreases during the joining pass.

The expected body count is 80 + 6 + 84 + 6 = 176 stitches. Unequal front and back counts are retained in this example; there is no arithmetic reason to make them equal.

Section completed	Stitches worked or added	Running total
Front	80	80
First underarm cast-on	6	86
Back	84	170
Second underarm cast-on	6	176

Use the sectional counts to diagnose a mismatch. A total of 170 is six stitches short, which makes an omitted bridge worth checking first. A total of 178 is two stitches over, so recount both bridges and confirm whether an existing panel stitch was mistakenly included in each cast-on count. These are diagnostic possibilities derived from the example, not proof of a particular error.

For your own project, calculate front + back + first underarm + second underarm, then include any increases or decreases explicitly required during the joining pass. Compare that result with the pattern’s stated total before continuing.

Once the circle is joined, continue in the round rather than turning at the former panel edges. Work every new underarm stitch when you reach it, following the body instructions for those stitches. Circular knitting keeps the outside of the tube facing you, so consult the pattern’s instructions for working its texture in rounds. How to knit in the round.

For a useful inspection, pause after the first complete circuit and check three things separately: the total count, the number of stitches in each bridge, and the route of the fabric around the needle. A correct total alone cannot confirm that the stitches are distributed correctly. In the example above, bridges of five and seven stitches would still total 176, although each should contain six.

If you find a count error, identify its location before adding or decreasing stitches elsewhere. Restoring the intended bridge count preserves the relationship between the underarm and any later marker-based instructions. If you find a twist, return to the joining point and correct the orientation before building more fabric.

The cast-on bridges also provide edges for later sleeve work when the design calls for it. La Visch Designs demonstrates picking up stitches from the underarm cast-on and recommends catching two strands rather than a single strand at the pickup point. Follow your garment’s own pickup count and finishing instructions. Underarm pickup guidance.

Before continuing down the body, make one final comparison with your notes: both panels are connected, both bridges have their prescribed counts, the fabric is untwisted, and the beginning-of-round marker matches the pattern. With those checks complete, continue the body from the joined stitches and retain the underarm counts for the later sleeve or armhole instructions.

• Inverleith KAL – Casting On Mid-Row and Joining the Body — Ysolda
• Tutorial – Casting On at the Underarm for Garments — La Visch Designs
• The Knitted On Cast-On — La Visch Designs
• Learn to Knit: How to Knit in the Round — Ysolda
• Classic Knit Jacket — Purl Soho