How to measure a bikini
Every point, drawn on the garment so there is no guessing where the tape goes.
Quick answer
A bikini is two pieces; this spec maps the bottom. Lay it flat and relaxed and measure front rise, back rise, height and width, in fit-impact order. Stretchy swim fabric means front rise is read unstretched, the relaxed line most listings skip. Hover or tap each step on the diagram to see the tape. Sizely builds a chart buyers trust.
A buyer judging a bikini bottom checks front rise and coverage first, then width across the hips, and the back rise tells them how the seat sits. Most swim listings give a single label and no numbers. Bikini bottoms carry negative ease, cut smaller than the body so the fabric stretches to fit, so a flat number reads smaller than the body it covers. This page draws each point on the relaxed garment, so your reading matches the buyer's at home.
- A
Front Rise
The fit-decider for coverage, so it leads. Run the tape up the center front from the crotch seam to the top front edge, suit flat and relaxed. Tap this step to see the line; pulling the fabric here is what turns a flattering listing into a return.Recorded as-is. Do not double.
- B
Back Rise
Up the center back from the crotch seam to the top back edge, kept flat and relaxed. A taller back rise means fuller seat coverage; a shorter one reads cheeky. This is the second thing a buyer weighs after the front.Recorded as-is. Do not double.
- C
Height
The side height, taken down the side seam from the top edge to the leg opening. It tells a buyer how high the bottom sits on the hip before any stretch.Recorded as-is. Do not double.
- D
Width
Across the bottom at its widest point, flat and relaxed. This is the across reading that maps to how the piece wraps the hips, so double it to reach a body number.Double it for the full hip circumference, then note that stretch adds reach beyond that.
- E
Width
Across the bottom at its widest point, flat and relaxed. This is the across reading that maps to how the piece wraps the hips, so double it to reach a body number.Double it for the full hip circumference, then note that stretch adds reach beyond that.
Measure flat and relaxed, never stretched. Smooth the bottom out and let the elastic return to its natural length before the tape goes down, because swimwear is built with negative ease and any tug inflates the figure. Width is an across run that doubles to a body circumference; front rise, back rise and height are single runs recorded exactly as measured.
Bikini size reference
| Size | Front Rise | Back Rise | Height | Width |
|---|---|---|---|---|
| XS | 6 | 8 | 3 | 7 |
| S | 6.5 | 8.5 | 3.5 | 7.5 |
| M | 7 | 9 | 4 | 8 |
| L | 7.5 | 9.5 | 4.5 | 8.5 |
| XL | 8 | 10 | 5 | 9.5 |
Frequently asked
What does a bikini measurement spec actually measure?
This spec covers the bikini bottom, the piece where fit and coverage make or break a sale. You record front rise and back rise for how high it sits front and back, side height for how it sits on the hip, and width across for the hip wrap. For the top, sellers usually list band and cup separately, the same way a bra is measured.
Should I measure a bikini stretched or relaxed?
Relaxed, every time. Swim fabric stretches a lot, so a pulled reading is meaningless to a buyer. Lay the piece flat, let the elastic settle to its resting length, and measure from there. A buyer doing the same with a bikini they already own will land on the same numbers, which is exactly what a chart is for.
Why is the bikini flat measurement smaller than my body?
Bikinis are cut with negative ease, so the pattern is smaller than the body and the fabric stretches to fit. A flat width of 8 inches, doubled to 16, can comfortably wrap a hip several inches larger. List the relaxed flat numbers and let buyers compare to a bikini they own rather than to a body tape.
Do I double any bikini measurement?
Only width, since it is taken across one flat layer; double it to estimate the hip circumference. Front rise, back rise and side height are single vertical runs, so the flat number is already the real number. Most charts list the relaxed flat figures because a buyer can verify them against a piece they own.
What size bikini am I in US, UK and EU?
Bikini labels jump around between regions, so a medium in one brand maps to a different number elsewhere. For the full cross-region conversion, see our women's international size chart. Pairing that chart with your own relaxed flat numbers gives an overseas buyer everything they need to choose.
Should I list a bikini in inches or centimeters?
Either is fine, as long as you stay consistent and label the unit. Swimwear sells across borders, so showing both helps, since one shopper thinks in inches and another in centimeters. Sizely puts both on every chart so no buyer has to convert a relaxed measurement in their head.
Related size charts & tools
Women's international size chart
Men's international size chartSources: Sizely garment engine, spec #93 (Bikini Set), named bottom measurement points. ISO 8559 body-measurement standard (representative ranges only). Last verified June 2026.
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