Measurements you need
Tape horizontally across the most prominent points of the bust, at the back — slightly above the shoulder blades, under the arms. In your usual underwear, not pulled tight.Tape horizontally across the most prominent points of the bust, at the back — slightly above the shoulder blades, under the arms. In your usual underwear, not pulled tight.
Usually 31½–51⅛ in.Usually 80–130 cm.Tape horizontally right under the bust, snug but not tight; at the back — at the same height. The difference from the bust shows the bust volume: the cup height depends on it.Tape horizontally right under the bust, snug but not tight; at the back — at the same height. The difference from the bust shows the bust volume: the cup height depends on it.
Usually 3⅞–6¼ in less than the bust.Usually 10–16 cm less than the bust.Tape horizontal around the fullest part of your buttocks, allowing for the curve of your stomach. Stand straight, feet together.Tape horizontal around the fullest part of your buttocks, allowing for the curve of your stomach. Stand straight, feet together.
Usually 33⅛–51⅛ in.Usually 84–130 cm.Tape horizontal around the narrowest part of your torso, usually ¾–1⅝ in above the navel. Snug but not tight; don't pull in your stomach.Tape horizontal around the narrowest part of your torso, usually 2–4 cm above the navel. Snug but not tight; don't pull in your stomach.
Usually 22⅞–43¼ in.Usually 58–110 cm.At the side, from the waistline down to the level where you measured the hip. It helps to tie a ribbon at the waist and measure from it.At the side, from the waistline down to the level where you measured the hip. It helps to tie a ribbon at the waist and measure from it.
Usually 7⅛–8⅝ in.Usually 18–22 cm.From the front waist, between the legs, to the back waist. Tape not pulled tight. Optional measurement: the pattern maker uses it to check the seat seam.From the front waist, between the legs, to the back waist. Tape not pulled tight. Optional measurement: the pattern maker uses it to check the seat seam.
Usually 23⅝–29½ in.Usually 60–75 cm.How the swimsuit is drafted
The cup is a triangle with slightly curved sides and base. The base width and height grow with the bust, and the cup depth is set by the difference between the bust and underbust. The bottom of the cup is folded into a casing for the underbust tie; the neck ties are sewn into the points. The tie-side bottoms are one piece on the fold: front, crotch and back. The center length is the crotch length at 3⅛ in8 cm below the waist, reduced by 5% because the fabric stretches less lengthwise. The back is wider than the front by 2 in5 cm, and the narrowest point is at the crotch, at 0.41 of the front length.
We checked the draft against proven commercial patterns for the same style: the main measurements match.
The pattern maker checks the draft itself: the cup sides are equal, there is enough tie for a bow, the seat length, the crotch width and the leg opening. If the leg opening comes out too tight, the pattern maker raises the corners of the bottoms. The results are in the “Draft check” section.
How to sew
Place the cup and lining right sides together and stitch the sides, inserting the neck tie into the point. Turn right side out, fold the bottom into a casing and thread the underbust tie through. Baste the bottoms to the lining, sew elastic along the leg openings and the top, fold under and topstitch with a zigzag; sew the ties into the corners.
How to print and tape
Download the PDF on Letter or A4 sheets and print at 100% scale, without “fit to page”. The first sheet has the test square: measure it with a ruler. The sheets are taped together with an overlap along the ⅜ in1 cm strips; sheet numbers and the assembly diagram are on the first page. For a copy shop or plotter, choose “One-sheet PDF”.
What you get
The cup and bottoms at full size, with seam allowances, casing allowance and hem allowance for elastic. Cut each piece from the main fabric and from the lining. Tie and elastic lengths are under the drawing.
FAQ
How do I choose the cup size?
From two measurements: bust and underbust. The bigger the difference between them, the taller and wider the triangle. With a difference of 4¾ in12 cm the cup is the same as on ready-made mid-size bikini patterns; for every ¾ in2 cm of difference beyond that, the cup is about ⅜ in1 cm taller. The triangles slide freely along the underbust tie — you can move them closer together or further apart.
Which bottoms should I choose?
Tie-side bottoms are one piece from front to back, with no side seams, and ties at the sides: easy to adjust to your fit. With side seams — classic bottoms with a gusset; the rise is low, mid or high to the waist. These also need the waist and hip depth measurements.
How do I make the ties?
Cut strips from the same fabric along the grainline, where it stretches less, four times the width of the finished tie. Fold the edges to the center, then in half and stitch — or sew into a tube and turn. The pattern maker gives the lengths under the drawing: underbust — bust plus allowance for a bow, two neck ties of 23⅝–27½ in60–70 cm, four bottom ties of 15¾ in40 cm.
What fabric should I use?
Swimwear lycra with 15–20% elastane. The cups and bottoms are lined: cut each piece again from lining mesh or thin swimwear lycra. Stretch 3⅞ in10 cm of fabric across: up to 5⅛ in13 cm is low stretch, 13–16 medium, more is high stretch.