The Antikythera One-Shoulder Bikini Free Sewing Pattern

Meet the Antikythera One-Shoulder Bikini, a playful yet practical swim set designed for sunny beach days, poolside lounging, and everything in between. Made with Mood’s Recycled Swimwear Tricot from the Santorini Collection, this bikini combines comfort, stretch, and support with built-in UV protection and over 30 vibrant shades to choose from. Whether you gravitate toward timeless black or a bright summer color, this quick project is the perfect excuse to sew yourself more than one.

The asymmetrical one-shoulder silhouette is topped with a soft ruffle for a flirty, feminine touch, while the wide bust band keeps everything comfortably secure for actual swimming and movement. Paired with high-waisted bottoms featuring flattering ruched sides, the Antikythera Bikini is equal parts cute, supportive, and confidence-boosting on sewists of any age.

With only 7 pattern pieces and 7 simple steps to complete, this beginner-friendly swimwear project comes together surprisingly fast. It’s the kind of instant-gratification make you’ll want to recreate again and again in different shades, prints, and textures of swimwear fabrics.

Essential Materials & Sizing Guide for the Antikythera One-Shoulder Bikini

Continue reading for a breakdown of what knowledge and materials you need for creating your very own one-shoulder bikini! We’ve got you covered with the recommended materials we used—if you want to follow along exactly—as well as a curated list of alternative fabric type recommendations if you want to customize your own version. The Antikythera One-Shoulder Bikini free sewing pattern download includes technical drawings for seam and one-shoulder bikini visibility, plus a size chart to help you find your perfect fit!

Purchase Products Used Below:

Quantities indicated are for sewing a size small* one-shoulder bikini. Toggle the ‘SHOP THIS LOOK’ box to find quantity estimates for other sizes.

• 1.5 yards of Recycled Swimwear Tricot, UV Protective – Nero – Santorini Plus Collection
• 1 each of Dritz Cotton Swimwear Elastic – 0.25″
• 1 each of Gutermann Sew All Thread 500m – 10 Black
• MDF531 – Antikythera One-Shoulder Bikini Sewing Pattern (Free download below!)

Additional Products Used:

• Lining Fabric for Gusset (you can really use any scrap piece of stretch knit fabric for the gusset)
• Ball Point Machine Needles

*Quick Tip! The ‘SHOP THIS LOOK’ box defaults to full-yard quantities. To order an exact half-yard quantity for any fabric, simply use the decrease quantity button (-) to subtract by the half yard. Then click “ADD TO CART” to add all materials to your cart. (Our system can only display full-yard quantities initially.)

Alternative Fabric Type Recommendations:

The Antikythera One-Shoulder Bikini sewing pattern is best suited for light or medium weight stretch knit fashion fabrics. Explore other fabric types or colors from our featured collections for your one-shoulder bikini with the links below.

• Spandex
• Compression Fabric
• Velour

Fabric Collections Used in this Post:

• Santorini Plus Collection

Download Your Free Sewing Pattern

Submit your name and email in the form below to receive the download link for the Antikythera One-Shoulder Bikini free sewing pattern directly in your inbox. Mood Sewciety Patterns will send your free download link via email with the subject line: ‘Your Free Download from Mood Sewciety – The Antikythera One-Shoulder Bikini’ (in PDF format for A4 and letter-size printing).

© MoodFabrics.com / MoodSewciety.com – Mass production, resale, or distribution of this pattern in any form is strictly prohibited.

Find Your Perfect Fit

The Antikythera One-Shoulder Bikini Sizing Guide is based on the suggested design & wearing ease for this style. You can also choose the size according to your desired finished garment measurements, blending between sizes as needed. Measure the printed patterns to make sure the dimensions are according to the desired fitting and adjust if needed before cutting the fabric. For best results, sew a test garment in a similar fabric to adjust your pattern

Measurements may vary after adjustments. If using non-stretch fabrics, reference the approximate finished garment measurements chart to choose your size.

Note: Always read all the instructions before cutting the fabric!

How to Sew The Antikythera One-Shoulder Bikini

The instructions provided below are designed to guide you through sewing the Antikythera One-Shoulder Bikini from start to finish.

3 Tips for Sewing with Tricot

⇒ Make sure to switch out the needle on your sewing machine for a ballpoint needle, which is made for stretch fabrics.

⇒ Use a rotary cutter and self-healing cutting mat to cut out the pattern pieces. It will prevent the fabric from moving around as much as you’re cutting and will ensure your pattern pieces are symmetrical.

⇒ Use a zigzag stitch to connect ALL your pieces together. This will allow the fabric to stretch with you without popping seams open.

Pattern Pieces & Fabric Cuts Needed

• (A) TOP BACK
  • Fabric – Cut 1
• (B) TOP FRONT
  • Fabric – Cut 1
• (C) TOP RUFFLE
  • Fabric – Cut 1 on Fold
• (D) TOP WAISTBAND
  • Fabric – Cut 1
• (E) BOTTOM BACK
  • Fabric – Cut 1 on Fold
• (F) BOTTOM FRONT
  • Fabric – Cut 1 on Fold
• (G) GUSSET
  • Fabric – Cut 1 on Fold

Sew with a 1/2″ seam allowance for all seams unless otherwise specified.

Step 1

SIDE & SHOULDER SEAMS

1. NOTE: Before cutting out your pattern pieces, decide on which side you’d like the shoulder strap to go.
2. Place the front top and the back top pieces right sides together with the sides and shoulders lined up.
3. Pin and sew the side and shoulder seams of the bikini top.

Step 2

TOP WAISTBAND

1. Fold the top waistband right sides together with the two short ends of the waistband meeting.
2. Pin and sew the raw edges of the short side of the waistband.
3. Fold the waistband wrong sides together longways with the seam allowance hidden inside of the waistband.
4. Pin the raw edges of the folded waistband to the raw edge of the bottom of the bikini top.
5. Sew along the pins.

Step 3

FINISH ARMSCYE

1. Fold the raw edges of the armscye in toward the wrong side of the bikini top.
2. Sew around the armscye with a zigzag stitch to secure the raw edges of the armscye in place.
3. Press the armscye hem.

Step 4

RUFFLE

1. Pin the RIGHT side of the ruffle to the WRONG side of the neckline of the bikini stop.
2. Sew along the pins.
3. Sew the seam allowance of the ruffle to the inside of the neckline by understitching with a zigzag stitch.

Step 5

GUSSET

1. Place the RIGHT SIDE of the gusset against the WRONG SIDE of the back of the bikini bottoms.
2. Place the RIGHT SIDE of the back of the bikini bottoms against the RIGHT SIDE of the front of the bikini bottoms (before sewing, the layers should be like this: front and back bikini bottoms right sides together and pinned at the crotch, right side of gusset piece against wrong side of back bikini bottoms).
3. Pin the layers together and sew.
4. Press the gusset seam flat.

Step 6 

GATHER BOTTOMS

1. Sew two parallel gathering stitches with a stitch length of 4 millimeters along all 4 open side seams of the bikini bottoms. Make sure to only sew the gather stitches along the top half of the side seams.
2. Gather the stitches as much as you can.
3. Pin the front and back bikini bottom pieces together at the side seams, making sure to secure the gathers with a short and narrow zigzag stitch.

Step 7

ELASTIC

1. Cut a piece of elastic for the waistband of the bikini bottoms that is 1 inch shorter than the circumference of the unstretched waistline of the bikini bottoms.
2. Cut 2 pieces of elastic for the bikini bottom leg openings that are 1 inch shorter than the circumference of the unstretched leg openings.
3. Pin the elastic evenly around the bikini bottom waistline and leg openings with the raw edges of the openings folded over onto the elastic.
4. Sew over the elastic and the folded edge of the bikini bottom openings with a zigzag stitch.

Sewing Success: The Finished Antikythera One-Shoulder Bikini

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We hope you had as much fun sewing this one-shoulder bikini pattern as we did! As always, we want to hear from you—share your thoughts and comments below and let us know where you’ll be wearing the Antikythera One-Shoulder Bikini free sewing pattern!

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