Triangular Seashell Bikini Top (Crochet)

Designer: PurlJam for PurlJam Studio (purljam.verde.uk) • Support: team@verde.uk • Social: #purljam

Overview

A light, textured triangular bikini top featuring a scalloped seashell stitch. Fully customizable for cup sizes XS–XL, with adjustable ties. Worked in crochet in two identical cups joined with an optional center tie or band. Suitable for cotton/nylon swim yarn or a cotton blend for best support and quick drying.

Sizes

• XS: Cup width 12 cm / 4.7 in; cup height 11 cm / 4.3 in
• S: Cup width 14 cm / 5.5 in; cup height 12 cm / 4.7 in
• M: Cup width 16 cm / 6.3 in; cup height 13.5 cm / 5.3 in
• L: Cup width 18 cm / 7.1 in; cup height 15 cm / 5.9 in
• XL: Cup width 20 cm / 7.9 in; cup height 16.5 cm / 6.5 in

Materials

• Yarn: Cotton/nylon blend (recommended for swimwear); DK / Light Worsted. Recommended yarn yardage per size (approx): XS 150 yd / 137 m (~70 g / 2.5 oz), S 180 yd / 165 m (~80 g / 2.8 oz), M 220 yd / 201 m (~100 g / 3.5 oz), L 260 yd / 238 m (~120 g / 4.2 oz), XL 320 yd / 293 m (~150 g / 5.3 oz). Use a tight-ish gauge yarn for support.
• Hook & needle sizes (give options):
  • Crochet hook: US G/6 (4.0 mm) | UK 8 | Metric 4.0 mm — recommended
  • Alternate crochet hooks: US F/5 (3.75 mm) | UK 9 | Metric 3.75 mm (for firmer fabric), or US H/8 (5.0 mm) | UK 6 | Metric 5.0 mm (for looser)
  • Knitting needle (if adapting pattern): US 6 | UK 4 | Metric 4.0 mm — for reference only
• Notions: tapestry needle, stitch markers (2), measuring tape, optional clear swimwear elastic 1/4" / 6 mm wide for reinforcing underband, swim-safe lining fabric (optional), small elastic rings or beads for tie ends (optional)

Gauge

10 cm x 10 cm (4" x 4") = 14 pattern sts x 8 rows using 4.0 mm hook in shell pattern. Gauge affects cup size — adjust hook if necessary.

Abbreviations (US crochet terms)

• ch = chain
• sc = single crochet
• hdc = half double crochet
• dc = double crochet
tr = treble crochet
• st(s) = stitch(es)
• sp = space
• sk = skip
• sl st = slip stitch
• RS = right side
• WS = wrong side

Special Stitches

• Shell (US): 5 dc in same stitch or space (5-dc shell). For a tighter shell you can do 4 dc.
• Seashell edge: *sc, ch2, sc* in scallop spaces (used for edging).

Notes

• Pattern uses a mirrored pair of triangular cups. Work one cup, then the second. Join cups with a center tie or a continuous band per your preference.
• Keep tension slightly firmer than usual for better support.
• If you want more coverage, increase the number of starting chains (see size-specific foundation counts below) or use a smaller hook.

Foundation and Cup Chart (Crochet)

Each cup is worked flat. The pattern repeat is a multiple of 6 + 1 stitches (for shell placement and edges). Below are foundation chain counts for each size (multiple of 6 + 1):

• XS: ch 25 (24 + 1)
• S: ch 31 (30 + 1)
• M: ch 37 (36 + 1)
• L: ch 43 (42 + 1)
• XL: ch 49 (48 + 1)

Cup Pattern (worked twice, make 2)

Start: Work on foundation chain (counts above). Optional: place a stitch marker in the final chain to mark start.

Row 0: ch (foundation), turn. Count back from hook to ensure correct multiple.
Row 1 (RS): In 2nd ch from hook, sc. *sk 2 ch, 5 dc in next ch (shell made), sk 2 ch, sc in next ch*; repeat from * to * across to last ch; sc in last ch. Turn.
Row 2 (WS): ch 2 (counts as hdc), hdc in first sc, *ch 1, sk the top 2 dc of the shell below and work 1 hdc in the center dc of the shell (this sits in the shell center), ch 1, hdc in next sc*; repeat across, ending with hdc in top of turning ch. Turn.
Row 3 (RS): ch 3 (counts as dc), dc in same st, *sk next hdc, 5 dc in next hdc (shell), sk next hdc, dc in next hdc, dc in next hdc*; repeat across, ending with dc in turning ch. Turn.
Row 4 (WS): ch 2, hdc in first st, *hdc in each st across until center of shell; in shell center work hdc, ch1, hdc to create the bed for next row shells*; repeat across. Turn.
Repeat Rows 3–4 until the cup reaches desired height: XS 11 cm, S 12 cm, M 13.5 cm, L 15 cm, XL 16.5 cm. End on a WS row (Row 2/4 style) so the final RS is shaped for edging.
Note: For a smoother triangle point, decrease 1 repeat (6 sts) off the center at the last 2–3 rows: on RS rows, before shell placement, work dc2tog once on each side of center to reduce width slightly at the tip. For most sizes this is optional; adjust for a neat point.

Finishing Each Cup

1. Weave in ends with tapestry needle.
2. Optional: add a 1/4" (6 mm) clear swimwear elastic along the bottom edge: single crochet along the lower edge, stretching elastic slightly to fit; stitch elastic to wrong side with small whip stitches.
3. Block lightly by pinning to measured dimensions and spritzing with water; do not soak if yarn includes nylon — allow to air dry flat.

Joining Cups

Two options:

1) Center Tie (separate)

1. Lay cups RS together with desired gap (2–6 cm / 1"–2.5" depending on cleavage preference).
2. Attach yarn at inner lower corner of left cup. sc evenly along inner edge of left cup to create a neat edge (about 6–10 sc depending on cup depth). Ch 80–100 (or desired length) for center tie, join to corresponding inner edge of right cup with sc and fasten off. The ch length becomes the tie you knot at front.

2) Underband (continuous)

1. With RS facing, join yarn at outer lower corner of left cup. sc along the bottom edge of left cup, making sure to place sc evenly across the shells (place 1 sc per shell center and 1sc in edge shells). Continue with chs to span across chest between cups (measure across for fit) so that when you reach the inner lower corner of the right cup you can sc up along the inner edge of the right cup mirroring the left.
2. Once both cups are connected, sc evenly around the entire lower edge to create a finished underband edge. Optionally work 2-3 rows of sc or hdc for a firmer underband. Insert swim elastic inside the band and stitch in place if desired.

Shoulder / Neck Ties

• For halter ties: attach at outer upper tip of each cup, ch 120–160 (adjust per wearer) and fasten off; finish ends with a small bead or knot.
• For shoulder straps: attach at outer top corners and work 3 rows of sc to desired length for over-the-shoulder support. Attach to back band or tie behind with ch length.

Edge Finishing — Seashell Scallop

With RS facing, join yarn at top outer corner.
Round: sc evenly around cup edge until you reach a shell tip space; in shell tip space work: (sc, ch2, sc) to create a scallop. Continue sc around, placing scallops at each shell seam or desired interval. Fasten off and weave in ends.

Lining & Cups Support

• Optional: cut swim-safe lining pieces to match the cup shape and hand-stitch to wrong side with small slip stitches for modesty and additional support.
• For maximum support, sew a thin layer of foam or removable padding inside the lining pocket (if you create one).

Care

• Hand wash cold in mild detergent; rinse well. Do not wring — press gently between towels to remove water. Reshape and dry flat out of direct sun.
• Avoid chlorine and oils—rinse promptly after use.

Tips & Customization

• To make more coverage, increase starting chain by one repeat (6 sts) and add 1–2 shell rows for extra height.
• Change shell size (4-dc vs 5-dc) for a tighter or more lacy look.
• Add a decorative tie at center made of chain sewn into a loop with a slider bead for adjustability.

Stitch Map Summary (Quick)

Foundation ch (multiple 6 + 1) → Row 1 sc + shells across → Row 2 pattern bed hdc → Repeat shell rows until height reached → Optional decreases for point → Edging and ties/band → Finishing touches.

Abbreviated Pattern (Example: Size M)

Make 2 cups:
ch 37.
Row 1: sc in 2nd ch from hook, *sk2, 5dc in next ch, sk2, sc in next ch*; repeat to end, sc in last ch. Turn.
Row 2: ch2, hdc in first sc, *ch1, hdc in center dc of shell, ch1, hdc in next sc* across. Turn.
Row 3: ch3, dc in same st, *sk 1 hdc, 5dc in next hdc, sk1 hdc, dc in next hdc, dc in next hdc* across. Turn.
Repeat Rows 2–3 to 13.5 cm height (end on WS). Finish edges and join cups with preferred method.

Notes on Sizing & Fit

Always make a gauge swatch and adjust hook to match gauge. Test fit before joining cups permanently — ties allow you to alter fit easily.

Copyright & Support

Pattern by PurlJam Studio. For questions or pattern support contact team@verde.uk. Share your projects with our community: tag #purljam.

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