What you need before you start sewing

A bikini is two separate pieces — a top and bottoms — each made from a straightforward pattern and sewn together with elastic and binding. You do not need advanced sewing skills. What you do need is a pattern (either printed or traced from an existing bikini), fabric suited to swimwear, elastic, thread, and basic tools: scissors, pins, a needle or sewing machine, and a measuring tape.

The fabric matters most. Swimwear fabric is stretchy and designed to dry quickly; regular cotton will absorb water and sag. Look for spandex blends or nylon lycra at fabric stores — these are labeled for swimwear. You will also need swimwear elastic, which is narrower and more flexible than regular elastic, and polyester or nylon thread that matches your fabric color.

If you are sewing by hand, you can finish a straightforward bikini in a few hours. A sewing machine makes the work faster and the seams more durable, but it is not required. Many people hand-stitch their first bikini and machine-sew the second.

Key Takeaways

  • Swimwear fabric must be a spandex or nylon blend that stretches and dries quickly; regular cotton will not work.
  • A bikini pattern can come from a commercial sewing pattern, a PDF you read and print, or traced from a bikini you already own.
  • The top and bottoms are sewn separately, then elastic is attached to the leg openings, armholes, and waistband to finish the edges.
  • Hand-stitching works but takes longer; a sewing machine produces stronger seams and is worth learning if you plan to sew swimwear again.
  • Trying on the pieces before you attach elastic lets you adjust the fit without unpicking seams.

Finding or making a pattern

You have three routes: buy a commercial pattern, read a PDF pattern and print it at home, or trace an existing bikini you own. Commercial patterns come from companies like Simplicity, McCall's, or Vogue and are sold at fabric stores for $10 to $20. They include printed instructions and usually offer multiple sizes on one sheet. read patterns are cheaper (often $5 to $15) and come as a PDF file you print yourself on regular paper, then tape the pages together.

Tracing an existing bikini is free and gives you a fit you already know works. Lay the bikini flat on paper, trace around the outline with a pen, and mark where seams and elastic go. This method works best if the bikini is a style you want to copy exactly — if you want to change the neckline or add padding, a commercial pattern gives you more control.

Whichever route you choose, check that the pattern includes a size range that matches your measurements. Most patterns list bust, waist, and hip measurements for each size. Measure yourself at the fullest part of each area and pick the size closest to your measurements, not the size you normally wear in clothes.

Cutting and preparing the fabric pieces

Lay your fabric on a flat surface with the pattern pieces on top, pinned in place. Swimwear fabric has a direction — one way feels smoother than the other — so lay all pattern pieces the same direction to avoid color variation in the finished bikini. Cut slowly and carefully with sharp scissors or a rotary cutter. Mark the seam allowance (usually half an inch) with a pen or chalk so you know where to sew.

You will have four main pieces: two for the top (front and back) and two for the bottoms (front and back). Some patterns include side panels or cups; follow your pattern's layout. Once cut, lay the pieces out in order so you do not mix them up. If you are hand-sewing, this is a good time to thread your needle and tie a knot at the end.

Before you sew anything, try the pieces on your body or a dress form to check the fit. Swimwear fabric stretches, so the pieces will feel snug when flat but comfortable when worn. If something looks obviously wrong — too tight in the shoulders, too loose at the waist — adjust now by pinning the seams in a different place and trying again.

Sewing the seams together

Start with the top. Pin the front and back pieces together at the sides, with the right sides (the pretty sides) facing each other. Sew a straight seam half an inch from the edge, either by hand with a running stitch or by machine. Backstitch at the beginning and end to lock the thread. Repeat for the bottoms, sewing the front and back pieces together at the sides.

For the top, you also need to sew the two cup pieces together if your pattern includes them, or attach any padding or lining before you close the sides. Follow your pattern's order — it will tell you which seams to sew first. Once the main seams are done, try the pieces on again. The fit should be close to what you want, though still a bit loose because the elastic has not been attached yet.

If you are hand-sewing, use a needle and thread that matches your fabric. A running stitch (in and out, in and out) is strong enough for swimwear if you keep your stitches small and close together. A backstitch (going backward through the previous stitch) is even stronger and is what most hand-sewers use for seams. Machine-sewing is faster and produces a more uniform seam, but either method works.

Attaching elastic to finish the edges

Elastic is what holds a bikini in place and finishes the raw edges. You will attach it to the leg openings, armholes, and waistband. Measure the opening you are binding — for example, the waistband of the bottoms — and cut elastic about 10 percent shorter than that measurement. The elastic will stretch as you sew it on, pulling the fabric tight.

Pin the elastic to the inside of the opening, stretching it slightly as you go so it lies flat against the fabric. Sew it down with a zigzag stitch (by machine) or a small running stitch (by hand), sewing through the elastic and the fabric edge. The zigzag stitch is ideal because it stretches with the fabric; a straight stitch can break when you move. Once the elastic is sewn, fold it to the inside and sew it down again to create a finished edge that looks neat from both sides.

Repeat this process for all openings: both leg holes, both armholes, and the waistband. This is the most time-consuming part of the project, but it is also what makes the bikini wearable. Take your time and keep the stitches small and even.

Adding straps and closures

Most bikini tops have straps that tie at the neck and back. These can be made from the same swimwear fabric as the rest of the bikini, or from bias tape or ribbon. If you are using fabric, cut two strips about 2 inches wide and as long as you need them to reach from the back of the top to around your neck. Fold each strip in half lengthwise and sew the long edge closed, then turn it right-side out and press flat.

Sew the straps to the top at the marked points on your pattern, usually at the back shoulders and the center back. Test the length by tying them around your neck — they should reach comfortably without being too long or too short. If you want a halter-style top, attach both straps at the center back and tie them together at the neck. If you want a standard two-strap top, attach one strap at each back shoulder.

Some bikini bottoms have ties at the sides instead of an elastic waistband. If your pattern includes these, make them the same way as the straps and sew them to the side seams at the waist. Ties give you more control over the fit and are easier to adjust than elastic.

Trying on and adjusting the fit

Once all the seams are sewn and the elastic is attached, try the bikini on. It should feel snug but not painful, and it should not shift or gap when you move. If the top rides up or the bottoms slip down, the elastic is too loose — you can remove it and sew it again with less stretch, or add a second row of elastic for more grip. If the fit pinches or cuts into your skin, the elastic is too tight or the seams are in the wrong place.

Small adjustments are easier to make now than later. If a seam is in the wrong place, you can unpick it with a seam ripper (a small tool with a curved blade) and resew it. If the elastic is wrong, you can cut it out and try again. Once you are happy with the fit, try the bikini on in water if possible — chlorine or salt water will not hurt it, and you will know how it performs when wet.

Caring for your finished bikini

Rinse your bikini in fresh water after each use to remove chlorine, salt, or sunscreen. Hand-wash it in cool water with mild soap and lay it flat to dry, away from direct sunlight. Do not wring it or put it in the dryer — heat and wringing damage the elastic and the fabric. A well-made bikini will last several seasons if you care for it this way.

If the elastic loosens over time, you can replace it without resewing the whole bikini. Cut out the old elastic carefully, measure the opening again, and sew new elastic in the same way. This is a quick repair that extends the life of the garment.

Frequently Asked Questions

Can I use regular fabric instead of swimwear fabric?

Regular cotton or linen will absorb water and become heavy and saggy when wet. Swimwear fabric is designed to dry quickly and maintain its shape. If you cannot find swimwear fabric locally, you can order it online from fabric retailers. It costs about the same as regular fabric.

Do I need a sewing machine?

No. Hand-sewing works perfectly well for a bikini and is how many people make their first one. A machine is faster and produces more uniform seams, but it is not required. If you hand-sew, use small, tight stitches and a thread color that matches your fabric.

What if my bikini is too loose or too tight after I finish?

If it is too loose, you can remove the elastic with a seam ripper and sew it back with less stretch. If it is too tight, you can remove the elastic and sew it back with more stretch, or add a second row of elastic. Both are quick fixes that do not require resewing the whole garment.

How much fabric do I need?

Most bikini patterns require 1 to 2 yards of fabric total, depending on the size and style. Check your pattern's yardage requirement before you buy. Swimwear fabric is usually sold in half-yard increments, so you will likely buy 2 yards to have enough.

Can I add padding or cups to the top?

Yes. Swimwear padding and cups are sold at fabric stores and can be sewn into the top before you close the side seams. Sew them to the front pieces, then sew the front and back together. Your pattern may include instructions for this, or you can sew them in by hand using a whip stitch that does not show from the outside.