How this is calculated
Every pattern company publishes a body-measurement chart: the measurements of the idealised figure each size was drafted for. It is not a garment measurement, and it is not comparable with any other brand's chart. This tool reads your six measurements against the chart for the brand you selected and reports which size each one falls into.
The rule for a measurement that lands between two sizes is round up — the smallest size whose chart figure is at least your own. A garment can be taken in; letting it out means finding seam allowance that may not be there. The wearing-ease selector shifts your effective measurement before the lookup, which is how you land on the other side of a boundary deliberately rather than by accident.
Where the three zones disagree, that is not an error in your measuring — it is the normal consequence of a chart drafted to fixed proportions. The answer is to cut each zone on its own line and blend between them, which is exactly what the nested cutting lines on a multi-size pattern exist for.
The full bust adjustment
Commercial patterns are drafted for a B cup, which corresponds to roughly a two-inch difference between high bust and full bust. Your own difference is measured the same way, and the excess over two inches is what has to be added to the front:
- Under 2″ — no adjustment. Take your size from the full bust.
- 2″ to 3″ — borderline. Fine on a loose style; on a close-fitted bodice a half- to one-inch adjustment will improve it.
- Over 3″ — take your size from the high bust and add a full bust adjustment of about (difference − 2)″ across the full bust, which is half that on each front piece, since the piece is cut on the half.
Brands that draft more than one cup option replace this step entirely: instead of slashing and spreading, you choose the printed bust line that matches your difference. The tool switches to that workflow automatically when you select one of those brands.
Length
Height decides the overall length change against the height the brand drafts for — most publish somewhere between 5 ft 5 in and 5 ft 7 in. Where a brand publishes a back-waist-length column, that column is used for the bodice instead, because it is the measurement that actually decides where a waist seam lands. Where it does not, the bodice takes roughly 40% of the height difference and the skirt or leg takes the remaining 60%.
Worked example. High bust 36″, full bust 40″, waist 32″, hip 42″, height 5 ft 4 in, back waist length 16½″, cutting a dress from a Big 4 pattern.
Full bust 40″ lands exactly on the size 18 bust of 40″. Waist 32″ lands exactly on the size 18 waist of 32″. Hip 42″ lands exactly on the size 18 hip of 42″ — so on the face of it, a straight 18.
But high bust 36″ matches the size 14 bust of 36″, and the difference between high and full bust is 4″ — two inches more than the B cup the pattern was drafted with. So the shoulders, neck and armhole should come from the 14, with a full bust adjustment of 4 − 2 = 2″ total, which is 1″ on each front piece. Below the bust the line blends out to the 18 at the waist and stays there through the hip.
At 5 ft 4 in against a chart drafted for 5 ft 5–6 in, roughly 1½″ of length comes out overall — but the back waist length of 16½″ matches the size 14 figure exactly, so the bodice is already right and the whole reduction belongs in the skirt.
What this does not account for
- Finished garment measurements. Ease is drafted per pattern, not per brand. The same company's fitted shirt and oversized coat need different sizes from the same body. Always check the finished measurements printed on the tissue or envelope before cutting — they are the only figures that tell you how it will actually sit.
- Knit stretch. Patterns for stretch fabrics are drafted with negative ease, so the chart lookup here will read a size or more too large. Use the pattern's stretch guide instead.
- Posture and proportion. Shoulder slope, a rounded upper back, a swayback, a high or low bust apex, a deep versus wide ribcage. None of these are visible in six circumferences and all of them show up in a muslin.
- Petite and tall grading. The length figure here is a single overall adjustment. Proper petite grading also moves the armhole depth, the bust apex and the shoulder width, which is more than lengthening or shortening at the marked lines.
- Chart revisions. Brands change their charts without announcement. Each chart here links to its published source — if they disagree, the brand is right.
- Vintage patterns. Older Big 4 patterns predate the current chart, and single-size vintage patterns carry no nested lines to blend between at all.
Where the charts come from
All figures are the brands' own published body measurements, reproduced here as factual data and linked back to the page each came from. Measurements are facts and are not copyrightable as such; no brand's drawings, instructions or written guidance is reproduced. This site is not affiliated with any pattern company.
Common questions
My bust, waist and hip give three different sizes. Which do I cut?
All three. Cut each area on its own line and blend between them along the side seam with a smooth curve rather than a step. That is standard practice and it is the reason multi-size patterns print nested cutting lines in the first place. Cutting one straight size to match your largest measurement gives you a garment that is right in exactly one place.
Why is my pattern size so much bigger than my clothing size?
Ready-to-wear sizing has drifted downward for decades; pattern charts have barely moved. A pattern size is a coordinate in a chart, not a statement about you, and it means nothing outside the chart it came from. Sewists who have been at it a while stop noticing the number entirely.
Do I round up or round down between sizes?
This tool rounds up, because taking a garment in is easy and letting it out often is not. On a deliberately loose style, or when you are a hair over the boundary, rounding down is perfectly reasonable — set the ease selector to close-fitting and it will.
Should I go by body measurements or finished garment measurements?
Body measurements to find your starting size; finished measurements to decide whether you will like how it sits. The finished measurements include the designer's intended ease, which is why a size 14 shirt and a size 14 coat from the same company measure wildly differently.
My measurements are outside the brand's size range. Now what?
The tool says so rather than inventing a size. Grading a pattern beyond its published range is a patternmaking job — the block was never proportioned for it, and the further you push, the less reliable it gets. Switching to a brand whose range includes you is almost always less work and a better result.
Does this work for knits?
Not reliably. Knit patterns are drafted with negative ease — the finished garment is deliberately smaller than the body — so a body-measurement lookup reads high. Use the pattern's own stretch percentage guide for knits and treat this tool as a woven-fabric starting point.
What about the cup size on my bra?
Ignore it. Bra cup letters are measured against a band that changes with size, so a 32D and a 40D are not the same volume. Pattern cup is the difference between high bust and full bust, full stop. Plenty of people who buy a DD need no adjustment and plenty who buy a C need a large one.
Do I still need to make a muslin?
Yes. This gets you to a sensible starting size and a correct blend, which is the part beginners are usually left to guess at. It cannot see your posture, and a test garment in cheap fabric is still the only way to find out what your body is asking the pattern for.