Ipswich Swimsuit

from $16

Size Size guide

Pattern format

PDF pattern available in sizes 12-32; printed pattern available in sizes 12-28.

Soak up the sun in the Ipswich Swimsuit, an underwired swimsuit sewing pattern designed for big boobs in cup sizes C–H!

This modern pattern has two cleverly color-blocked variations: a one-piece swimsuit with a contrast waistband or a high-waisted bikini with piping detail. Both suits feature supportive straps, and an optional underwired foam swim bra and boning, so that you're comfortable lounging by the pool or playing volleyball on your favorite beach. Mix prints and colors for a swimsuit that celebrates your body and your creativity, and keeps you feeling secure all summer long.

This Cashmerette pattern includes:

  • Cup sizes from C to H
  • A sizing calculator which will tell you exactly which size to make
  • A beautifully illustrated and detailed instruction booklet, to guide you no matter your sewing level

Want step-by-step help making your Ipswich? Check out our online workshop “Swimsuit Making for Curves” where Jenny Rushmore will take you through the whole process with confidence!

Interested in making a tankini version of the Ipswich Swimsuit? A free expansion pack is available here

Product information




12to 32 (PDF pattern), 12 to 28 (printed pattern), in three cup sizes (C/D, E/F, G/H). Includes 40-62” bust and 42-62” hip. Find your size in seconds using our size calculator.


Swimsuit lycra/spandex, with 4-way stretch (at least 50% in both directions), swimsuit lining with 4-way stretch (at least 50% in both directional), optional contrast swimsuit/spandex for piping (View B). 


All Views

  • Stretch needle, polyester thread
View A (One-piece)
  • 5 yards (4.5 m) of ¼” – ⅜” (0.6 – 1 cm) rubber/swimwear elastic
  • 2 yards (1.8 m) of ½” – ⅝” (1.25 – 1.5 cm) bra strapping (or firm elastic)
  • 1 swimwear closure or S Hook (1” / 2.5 cm)

View B (Bikini)

  • 6 yards (5.5 m) of ¼” –⅜” (0.6 – 1 cm) rubber/swimwear elastic
  • 2 yards (1.8 m) of ½” – ⅝” (1.25 – 1.5 cm) bra strapping (or firm elastic)
  • 2 swimwear closures or S Hooks (1” / 2.5 cm)

Optional Swim Bra

  • 1 yard (0.9 m) of ⅝” (1.5 cm) wide Fold Over Elastic
  • 1 yard (0.9 m) of ¼” (6 mm) stay tape
  • ⅜ yard (35 cm) swim cup foam (45” / 115 cm wide)
  • ¼ yd (15 cm) of stable bra lining, like Duoplex (45” / 115 cm wide)
  • ⅜ yard (35 cm) of power mesh (45” / 115 cm wide)
  • 1 yard (0.9 m) of underwire channeling
  • 1 set of regular length underwires (coated steel or plastic)

Optional boning: 

  • ⅓ yard (28 cm) of pre-covered ¼” (6 mm) plastic boning, or ⅓ yard (28 cm) plastic boning plus ⅓ yard (28 cm) channeling.

Customer Reviews

Based on 13 reviews
Mary Powell
Quite a journey

This suit looks amazing once finished, but it was neither quick nor easy. The first challenge was fitting. While adequate instructions were provided for blending sizes for the waist and hip, no guidance was given for fitting bust. I normally make a do a full bust adjustment on Cashmerette's G/H cups and had no idea how to manage that with the built in bra. Jenny did provide a suggestion (to size up and then shorten the neckband and straps) once I emailed, but it would have been nice to have that included in the pattern. Second, there are at least three types of elastic used in the suit, FOE, swim, and strap, yet most of the time the instructions just say "elastic." After reading through the instructions multiple times, I concluded that swim elastic was meant whenever simply "elastic" was written. It turned out fine, so I hope it was right. Again, something extremely simple for the pattern writer to include clarification of. Lastly, the straps were a nightmare to attach. It would have been helpful to know whether the folded strap "sandwich" was meant to be flush with the edge of the suit (sewn at 5/8th seam allowance), or sewn at 3/8ths like the rest of the suit. I sewed at 5/8ths so that the end of the back band (part 15) looked as much like the picture as possible. Again, a few sentences of clarification would have saved a lot of struggle and half a bottle of wine.
All in all, the finished suit looks great. Subsequent suits will be easier, but oh boy did I almost give up.

Erika Abner
Swimsuit review

A great pattern. Highly recommend purchasing the video tutorial if you are new to making swimsuits. Fit well right out of the envelope. The only change I would make would be to stretch the elastic under the tush more than suggested. Am planning to make a tankini version.

Carolyn Wahlen

Thank you. This model needed a custom sized suit and your pattern provided what we needed.

Susan Kraterfield
Disappointed in suitability for large chests

I planned the "tankini" version of the suit, in one fabric. I make my own bras, so I used my own custom fitted bra pattern.

I had no trouble with the pattern or instructions but for 1 minor thing.. There is no indication of the pattern piece number on the cutting layouts. With so many similar shapes, I think it would have been better to make these graphics bigger and print the pattern piece numbers in the layout. I spent a lot of time going over the pattern inventory and studying everything and labelling each piece on the layout myself. Also, with the tankini download, I was a little uncertain re what pattern pieces to use since some places use view A and some view B and there was no indication for cutting except for the "contrast" fabric.

The top just doesn't work. Even though I made a complete custom fitted underwire bra there is no support through the back to lift and the spandex overlay just squashes me flat to a uni-boob. With 9" difference between my under bust & full bust, a flat spandex front doesn't work. The princess seams add no shaping. This will never be good enough to wear in public.

I'm going to keep the bottoms, cannibalize the skirt to make a real bra with a supportive band & hook/eye covered in spandex, and use leftover yardage for an A-line "skirt" to drape down over the hip w/ an open "apron" back where the hook/eye are.

Hi Susan - I'm sorry to hear the top of the Ipswich didn't work for you. It's designed to work with the underwired bra included in the pattern which includes back support; as you replaced that with your own bra pattern, it's hard to say exactly why it doesn't fit. If you want to share your measurements with us at hello@cashmerette.com we can help you find a better size that won't compress your bust.

Diane Robinson
Ipswich bathing suit is a win

Took a trip to Hawaii and needed a bathing suit. I hacked it into the tankini. It was amazing. The instructions were perfect step by step. Even though I am a seasoned seamstress, the inner branwas intimidating but I was confident with the instructions. I actually made two swimsuits and they were exactly what I wanted!