Easy Exercise Tank Top — Upper Body

Custom athletic tank from the underarm up

A beginner-friendly continuation for a bottom-up tank already knit in the round to the armpit. You will bind off a few underarm stitches, work the back and front separately with simple armhole and scoop-neck decreases, join the straps, and finish the neck and armholes with a short stretchy rib. Designed for movement: modest front neck, higher back neck, and straps about 2¼" wide.

Size

One custom size, matching the body on your needles.

• Finished bust / hem circumference: 37 inches (94 cm)
• Front width at underarm, before shaping: 17.5 inches (44.5 cm)
• Back width at underarm, before shaping: 17.5 inches (44.5 cm)
• Armhole depth to shoulder: 8½ inches (21.5 cm)
• Front neck depth (from underarm): 4 inches (10 cm) of knitting before neck bind-off, then a scoop
• Strap width: 8 stitches ≈ 2¼ inches (5.5 cm)

Materials

• Yarn: Worsted weight (medium / category 4), same yarn as the body. The upper body plus edgings use approximately 120–180 yards (110–165 m) in addition to yarn already used for the body.
• Needles: US 10.5 / 6.5 mm, the circular needle you have been using, plus a 16 inch (40 cm) circular or double-pointed needles in the same size for neck and armhole edgings (magic loop on a longer circular is also fine).
• Spare needle: US 10.5 / 6.5 mm for the 3-needle bind-off (or a darning needle if you prefer to sew the straps).
• Notions: 4 stitch markers, waste yarn or stitch holders, tapestry needle, scissors.

Gauge

As established on your body: 131 stitches = 37 inches (94 cm) in stockinette stitch in the round, approximately 14 stitches = 4 inches (10 cm) / 3½ stitches per inch.

Row gauge (guide only): about 20 rows = 4 inches (10 cm) / 5 rows per inch. If your row gauge is different, follow the inch measurements, not a row count. Try the tank on as you work the straps.

Abbreviations (US)

• BO — bind off
• BOR — beginning of round
• k — knit
• k2tog — knit 2 stitches together (right-leaning decrease)
• p — purl
• pm — place marker
• RS — right side
• ssk — slip 1 knitwise, slip 1 knitwise, insert left needle into the front of both slipped stitches and knit them together (left-leaning decrease)
• st(s) — stitch(es)
• St st — stockinette stitch (knit on RS, purl on WS when working flat)
• WS — wrong side

Pattern Notes

• This pattern starts at the underarm. It assumes you currently have 131 stitches in the round on US 10.5 / 6.5 mm needles, measuring 37 inches (94 cm) around.
• After the divide you will work flat (back and forth).
• Garter selvedge: on every flat row, knit the first stitch and knit the last stitch. This makes a tidy chain edge that is easy to pick up from later. Armhole and neck decreases are worked just inside that edge stitch.
• ssk is used on the right edge and k2tog on the left edge so the decreases lean into the fabric. If you prefer, you may use k2tog on both sides.
• Lengths are written in inches so you can follow your own row gauge. The decrease counts below are matched to a typical 5 rows-per-inch fabric; if you reach the stitch target early, work even; if you are still decreasing when the piece is long enough, join a slightly wider strap — both are wearable.
• Try it on. Armhole depth of 8½ inches (21.5 cm) is a standard athletic-tank starting point. Add or subtract length in the even sections (after decreases are finished) if you want more coverage or a deeper cut.

Instructions

1. Mark the underarms

Lay the tube flat so the front is 17.5 inches (44.5 cm) and the back is 17.5 inches (44.5 cm). The two side folds are your underarms.

Place a marker at each underarm fold. You will bind off 4 stitches centered on each fold (about 1 inch / 2.5 cm).

If your beginning of round is not already at a side, knit to the first underarm marker before starting the divide. Do not cut the yarn.

2. Divide for armholes

Next round (divide): Bind off 4 stitches for the first underarm, knit 62 stitches and place those 62 stitches on waste yarn or a holder for the Front, bind off 4 stitches for the second underarm, knit the remaining 61 stitches for the Back.

Check: 4 + 62 + 4 + 61 = 131 stitches ✓

You are now working the Back only, flat, on 61 stitches. The Front rests on waste yarn.

Turn the work so the WS is facing.

3. Back

Setup row (WS): K1, purl to last stitch, k1. (61 sts)

Armhole shaping

Decrease row (RS): K1, ssk, knit to last 3 stitches, k2tog, k1. (2 stitches decreased)

WS row: K1, purl to last stitch, k1.

Repeat the last 2 rows 3 more times (4 decrease rows total). 61 − 8 = 53 stitches ✓

Work even

Continue in stockinette with garter selvedges (k1 at each end of every row) until the armhole measures 7½ inches (19 cm) from the underarm bind-off, ending with a WS row.

Back neck and straps

Next row (RS): K10, bind off the center 33 stitches, k10. 10 + 33 + 10 = 53 stitches ✓

You now have two groups of 10 stitches. Work each strap separately. Attach a second ball (or work one strap, then rejoin yarn for the other).

Left back strap (as worn; the side you just finished):

• WS: K1, purl to last stitch, k1.
• Neck decrease (RS): Knit to last 3 stitches, k2tog, k1. (1 stitch decreased at neck)

Repeat the last 2 rows once more (2 neck decreases total). 10 − 2 = 8 stitches ✓

Work even in stockinette with garter selvedges until the armhole measures 8½ inches (21.5 cm) from the underarm bind-off, ending with a WS row. Place the 8 stitches on waste yarn.

Right back strap: With WS facing, join yarn at the neck edge.

• WS: K1, purl to last stitch, k1.
• Neck decrease (RS): K1, ssk, knit to end.

Repeat the last 2 rows once more (2 neck decreases total). 10 − 2 = 8 stitches ✓

Work even until this strap matches the left strap. Place the 8 stitches on waste yarn. Cut yarn, leaving a 12 inch (30 cm) tail.

4. Front

With RS facing, return the held 62 Front stitches to the needle. Join yarn at the right armhole edge (as worn).

Setup row (WS): K1, purl to last stitch, k1. (62 sts)

Armhole shaping

Decrease row (RS): K1, ssk, knit to last 3 stitches, k2tog, k1. (2 stitches decreased)

WS row: K1, purl to last stitch, k1.

Repeat the last 2 rows 3 more times (4 decrease rows total). 62 − 8 = 54 stitches ✓

Work even

Continue in stockinette with garter selvedges until the armhole measures 4 inches (10 cm) from the underarm bind-off, ending with a WS row.

Front neck and straps

Next row (RS): K19, bind off the center 16 stitches, k19. 19 + 16 + 19 = 54 stitches ✓

Work each side separately.

Left front strap (as worn; the side you just finished):

• WS: K1, purl to last stitch, k1.
• Neck decrease (RS): Knit to last 3 stitches, k2tog, k1.

Repeat the last 2 rows 10 more times (11 neck decreases total). 19 − 11 = 8 stitches ✓

Work even (if needed) until this strap is the same length as the Back straps, ending with a WS row. Place the 8 stitches on waste yarn.

Right front strap: With WS facing, join yarn at the neck edge.

• WS: K1, purl to last stitch, k1.
• Neck decrease (RS): K1, ssk, knit to end.

Repeat the last 2 rows 10 more times (11 neck decreases total). 19 − 11 = 8 stitches ✓

Work even until this strap matches the other Front strap and the Back straps. Leave stitches on the needle (or waste yarn). Do not cut the yarn if you will join with a 3-needle bind-off from this side; otherwise cut, leaving a 12 inch (30 cm) tail.

5. Join the straps

Turn the tank inside out so wrong sides are together and the Front and Back straps line up (8 stitches facing 8 stitches on each shoulder).

3-needle bind-off (beginner-friendly firm shoulder): Hold the Front and Back strap needles parallel. With a third needle, knit 1 stitch from the front needle together with 1 stitch from the back needle; repeat once; pass the first stitch over the second. Continue knitting one from each needle together and binding off until all 8 stitches are joined. (8 + 8 joined → 0 live stitches ✓)

Repeat for the second shoulder.

Alternative: Bind off each strap separately and sew the shoulders with mattress stitch.

Finishing

Armhole edging (make 2)

With RS facing and a 16 inch (40 cm) circular or double-pointed needles, beginning at the center of one underarm bind-off, pick up and knit stitches evenly around the armhole:

• 1 stitch in each bound-off underarm stitch
• about 3 stitches for every 4 rows along the vertical armhole edges

Aim for an even number of stitches so 1×1 rib lines up (add or skip 1 pickup if needed).

Place a marker for the beginning of round.

Rounds 1–5: *K1, p1; repeat from * to end of round.

Bind off loosely in rib.

Repeat for the second armhole.

Neck edging

With RS facing, beginning at the left shoulder seam (as worn), pick up and knit around the neck:

• stitches along the left front neck edge (about 3 for every 4 rows)
• 1 stitch in each bound-off stitch of the front neck
• stitches along the right front neck edge
• stitches along the right back neck edge
• 1 stitch in each bound-off stitch of the back neck
• stitches along the left back neck edge

Adjust by 1 stitch if needed so you have an even number.

Rounds 1–5: *K1, p1; repeat from * to end of round.

Bind off loosely in rib. The bind-off must be loose enough to fit over the head; if it feels tight, bind off with a needle one size larger.

Weave and block

Weave in all ends on the wrong side.

Wet-block the tank to measurements: 37 inches (94 cm) around the bust, armholes about 8½ inches (21.5 cm) deep, straps sitting on the shoulders. Pin the neck scoop smooth and let dry fully. Blocking evens the stockinette and sets the rib so the tank hangs well for exercise.

Fit checkpoints

• Underarm: 4 stitches bound off each side (4 + 62 + 4 + 61 = 131 ✓).
• After armhole decreases: Back 53 sts, Front 54 sts.
• Straps: 8 sts each (Back 10 − 2 = 8 ✓; Front 19 − 11 = 8 ✓).
• If straps feel narrow, stop decreasing 1–2 stitches sooner. If the neck feels high, begin the Front neck bind-off ½–1 inch earlier than 4 inches.