Baby crochet mermaid tail pattern featured image with a baby wearing a mint green crocheted mermaid tail and red starfish headband beside bold colorful text.

Baby crochet mermaid tail pattern

Turn your little one into a tiny mermaid with this sweet crochet mermaid tail. The tapered shape and large textured fin make it an adorable photo prop for baby pictures, Halloween, or a special handmade gift.

Quick answer

This advanced beginner baby crochet mermaid tail is worked from the bottom up in joined rounds using worsted weight (#4) yarn and a J-10 (6 mm) crochet hook. The pattern includes 0–3 month and 3–6 month sizes, with waist-length and chest-length options for each size. The fin is worked in rows directly onto the bottom of the finished tail.

Need a larger size? Try my crochet mermaid tail pattern for child, teen, and adult sizes.

Baby crochet mermaid tail pattern details

This section covers the skill level, sizes, materials, gauge, and important notes you’ll need before starting the baby crochet mermaid tail pattern.

Skill level

Advanced beginner — This pattern uses basic crochet stitches, joined rounds, increases, and rows worked in the front and back loops to shape the fin.

Materials needed

  • J-10 (6 mm) crochet hook
  • Worsted weight yarn (#4)
  • Yarn needle
  • Scissors

Size chart

Use the body measurements below to choose your baby mermaid tail size.

SizeChestWaistHips
0–3 months16 inches18 inches19 inches
3–6 months17 inches19 inches20 inches

Gauge

12 tr stitches and 6 tr rounds = 4 inches (10 cm), measured on the body of the tail using the J-10 (6 mm) crochet hook.

My guide to crochet gauge explains how to measure your stitches and adjust your hook size.

Baby crochet mermaid tail pattern featuring a mint green crocheted mermaid tail with large fin, worn by a baby with a red starfish headband.

Crochet abbreviations

  • tr = treble crochet
  • dc = double crochet stitch
  • sc = single crochet stitch
  • ch / chs = chain / chains
  • st / sts = stitch / stitches
  • rnd / rnds = round / rounds
  • sl st = slip stitch
  • BLO = back loop only
  • FLO = front loop only

Pattern notes

  • Make the tail first, then add the fin.
  • Choose waist-length or chest-length.
  • The fin pattern is the same for both sizes.
  • Worked in the round from the bottom up.
  • The beginning chain does not count as a stitch.
  • Join each round with a sl st to the first stitch.
  • Repeat instructions between the asterisks (*) around the round.
  • Safety note: This baby mermaid tail is intended for supervised use, such as photo shoots or dress-up. Do not use it for sleeping or leave a baby unattended while wearing it.
  • Written in US crochet terms.

Magic circle alternative

If you don’t like the magic circle: ch 5, make 12 tr in the 5th ch from the hook, join (12 sts).

Baby mermaid tail crochet pattern showing a baby in a mint green crocheted mermaid tail with a red starfish headband on a bright white background.

Crochet baby mermaid tail pattern instructions

Follow the step-by-step crochet instructions below to make the baby mermaid tail in either waist-length or chest-length, with sizes for 0–3 months and 3–6 months.

Want a matching accessory? Pair it with my starfish appliqué for a sweet headband.

0–3 month baby mermaid tail

Rnd 1: Magic circle, 12 tr, join (12)
Rnd 2: Ch 3, *2 tr in 3 sts, tr in 3 sts*, join (18)
Rnd 3: Ch 3, *2 tr in 2 sts, tr in 7 sts*, join (22)
Rnd 4: Ch 3, *2 tr in 2 sts, tr in 9 sts*, join (26)
Rnd 5: Ch 3, *2 tr in 2 sts, tr in 11 sts*, join (30)
Rnd 6: Ch 3, *2 tr in 2 sts, tr in 13 sts*, join (34)
Rnd 7: Ch 3, *2 tr in 3 sts, tr in 14 sts*, join (40)
Rnd 8: Ch 3, *2 tr in 3 sts, tr in 17 sts*, join (46)
Rnd 9: Ch 3, *2 tr in 3 sts, tr in 20 sts*, join (52)

Waist-length (0–3 months)
Rnds 10–20: Ch 3, tr in each st, join (52)
Rnd 21: Ch 1, sc in each st, join and fasten off

Chest-length (0–3 months)
Rnds 10–27: Ch 3, tr in each st, join (52)
Rnd 28: Ch 1, sc in each st, join and fasten off

3–6 month baby mermaid tail

Rnd 1: Magic circle, 12 tr, join (12)
Rnd 2: Ch 3, *2 tr in 3 sts, tr in 3 sts*, join (18)
Rnd 3: Ch 3, *2 tr in 2 sts, tr in 7 sts*, join (22)
Rnd 4: Ch 3, *2 tr in 2 sts, tr in 9 sts*, join (26)
Rnd 5: Ch 3, *2 tr in 2 sts, tr in 11 sts*, join (30)
Rnd 6: Ch 3, *2 tr in 2 sts, tr in 13 sts*, join (34)
Rnd 7: Ch 3, *2 tr in 3 sts, tr in 14 sts*, join (40)
Rnd 8: Ch 3, *2 tr in 3 sts, tr in 17 sts*, join (46)
Rnd 9: Ch 3, *2 tr in 3 sts, tr in 20 sts*, join (52)
Rnd 10: Ch 3, *2 tr in 3 sts, tr in 23 sts*, join (58)

Waist-length (3–6 months)
Rnds 11–23: Ch 3, tr in each st, join (58)
Rnd 24: Ch 1, sc in each st, join and fasten off

Chest-length (3–6 months)
Rnds 11–33: Ch 3, tr in each st, join (58)
Rnd 34: Ch 1, sc in each st, join and fasten off

Fin for the baby crochet mermaid tail pattern

Lay the mermaid tail flat with the increase section centered on the back of the tail. (figure 1)

Join yarn on the side of the tail between rounds 5 and 6. Chain 1 and single crochet in the same space. (figure 2)

Single crochet evenly around the lower edge of the flattened tail, working in the following order:

  • Down one side of the tail
  • Slip stitch in the center at the bottom
  • Up the opposite side

Continue until you reach the starting point between rounds 5 and 6. Do not fasten off. Begin the fin rows below. (figure 3)

Direction key:
→ = work away from the tail
← = work toward the tail

Fin rows:

← Row 1: Ch 36, dc in 2nd ch from hook and in each remaining ch, sl st in 2nd sc on tail (35 sts) (figure 4)


→ Row 2: Ch 2, dc in BLO across to the last st, leave the last st unworked. (34 sts)
← Row 3: Sl st in first st, ch 2, dc in FLO across, sl st in 3rd sc on tail. (33 sts)
→ Row 4: Ch 2, dc in BLO across to the last st, leave the last st unworked. (32 sts)
← Row 5: Sl st in first st, ch 2, dc in FLO across, sl st in 4th sc on tail. (31 sts)

→ Row 6: Ch 2, dc in BLO across to the last st, leave the last st unworked. (30 sts)
← Row 7: Sl st in first st, ch 2, dc in FLO across, sl st in 5th sc on tail. (29 sts)
→ Row 8: Ch 2, dc in BLO across to the last st, leave the last st unworked. (28 sts)
← Row 9: Sl st in first st, ch 2, dc in FLO across, sl st in 6th sc on tail. (27 sts)

→ Row 10: Ch 2, dc in BLO across to the last st, leave the last st unworked. (26 sts)
← Row 11: Sl st in first st, ch 2, dc in FLO across, sl st in 7th sc on tail. (25 sts)
→ Row 12: Ch 2, dc in BLO across to the last st, leave the last st unworked. (24 sts)
← Row 13: Sl st in first st, ch 2, dc in FLO across, sl st in 8th sc on tail. (23 sts)

→ Row 14: Ch 2, dc in BLO across to the last st, leave the last st unworked. (22 sts)
← Row 15: Sl st in first st, ch 2, dc in FLO across, sl st in 9th sc on tail. (21 sts)
→ Row 16: Ch 2, dc in BLO across to the last st, leave the last st unworked. (20 sts)
← Row 17: Sl st in first st, ch 2, dc in FLO across, sl st in 10th sc on tail. (19 sts)

→ Row 18: Ch 2, dc in BLO across to the last st, leave the last st unworked. (18 sts)
← Row 19: Sl st in first st, ch 2, dc in FLO across, sl st in 11th sc on tail. (17 sts)
→ Row 20: Ch 2, dc in BLO across, 2 dc in last st. (18 sts)
← Row 21: Ch 2, 2 dc in first st, dc in FLO across, sl st in 12th sc on tail. (19 sts)

→ Row 22: Ch 2, dc in BLO across, 2 dc in last st. (20 sts)
← Row 23: Ch 2, 2 dc in first st, dc in FLO across, sl st in 13th sc on tail. (21 sts)
→ Row 24: Ch 2, dc in BLO across, 2 dc in last st. (22 sts)
← Row 25: Ch 2, 2 dc in first st, dc in FLO across, sl st in 14th sc on tail. (23 sts)

→ Row 26: Ch 2, dc in BLO across, 2 dc in last st. (24 sts)
← Row 27: Ch 2, 2 dc in first st, dc in FLO across, sl st in 15th sc on tail. (25 sts)
→ Row 28: Ch 2, dc in BLO across, 2 dc in last st. (26 sts)
← Row 29: Ch 2, 2 dc in first st, dc in FLO across, sl st in 16th sc on tail. (27 sts)

→ Row 30: Ch 2, dc in BLO across, 2 dc in last st. (28 sts)
← Row 31: Ch 2, 2 dc in first st, dc in FLO across, sl st in 17th sc on tail. (29 sts)
→ Row 32: Ch 2, dc in BLO across, 2 dc in last st. (30 sts)
← Row 33: Ch 2, 2 dc in first st, dc in FLO across, sl st in 18th sc on tail. (31 sts)

→ Row 34: Ch 2, dc in BLO across, 2 dc in last st. (32 sts)
← Row 35: Ch 2, 2 dc in first st, dc in FLO across, sl st in 19th sc on tail. (33 sts)
→ Row 36: Ch 2, dc in BLO across, 2 dc in last st. (34 sts)
← Row 37: Ch 2, 2 dc in first st, dc in FLO across, sl st in 20th sc on tail. (35 sts)

Finishing

Fasten off and weave in all ends.

Printable PDF version

Prefer an ad-free, printable copy? You can get the PDF in my Etsy shop: Crochet Mermaid Tail Pattern.

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You can also visit my full collection of crochet baby patterns for more baby blankets, hats, cardigans, booties, outfits, and gifts.

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Happy crocheting! 🧶
— Melissa

Baby crochet mermaid tail pattern featuring a baby wearing a mint green crocheted mermaid tail and red starfish headband, with text highlighting an easy photo prop.