Reading a Size Chart When You Are Between Sizes

A size chart exists to answer one question, and most of them answer it ambiguously. Once you know what a chart is actually measuring, and how much room the garment is supposed to leave, the choice between two neighbouring sizes becomes a decision rather than a guess.

First, work out what the chart is measuring

There are two kinds of chart, and they are not interchangeable.

Body measurements describe the person the size is intended for. These numbers are drawn from the brand’s fit model and grading rules, and they include the room the designer expects to build in. A size chart saying a waist of a certain figure does not mean the garment’s waist measures that.

Garment measurements describe the finished item, laid flat. These are far more useful, and they are the ones to look for. If you find a chart with both, use the garment numbers.

If a chart lists a single measurement — usually bust — it is not telling you how the garment was graded. Two brands can have identical bust charts and completely different hip and upper-arm measurements, which is where the fit difference will actually appear.

Ease: the number nobody puts in the chart

Ease is the difference between your body and the garment. Every wearable garment has some; how much depends on what it is and how it is supposed to look.

• A structured jacket or coat needs enough ease to close over clothing and allow movement — think in terms of several centimetres over the bust and across the back.
• A fitted woven dress or blouse needs enough to move in without straining, but not so much that it floats.
• A good knit can be worn with very little ease, or even a little less than your body measurement, because the fabric stretches to meet you.

This is why the same bust measurement can produce a comfortable sweater and a dress that will not zip. When you are between sizes, ease decides it: for a structured garment with little stretch, take the larger size; for a knit with real recovery, the smaller size is usually right, because a knit that is too large tends to sag and lose its shape rather than adapt.

Measure the stretch before you trust it

“Stretch” on a product page can mean anything from a firm ponte to a light jersey that goes limp after a wash. You can measure it in a minute on something you already own, and the technique works the same way on a garment in a shop.

Take the fabric between both hands, ten centimetres apart, and stretch it sideways as far as it will comfortably go without distorting the knit. Note the new distance. A fabric that reaches around twelve or thirteen centimetres has modest stretch. One that reaches fifteen or more is highly elastic. Then let go and check whether it returns: a knit that stays stretched has poor recovery, and it will bag out at the elbow, the knee and the seat.

Apply the same test to the waistband of a pair of jeans or the cuff of a sleeve, and you will know quickly whether the garment will hold you or gradually give up.

Read the increments, not just the numbers

Subtract one size from the next in the chart. The pattern of jumps tells you what the brand assumed about the body it was building for.

If the hip jumps by a noticeably larger amount between your size and the next one while the waist barely moves, the brand has graded for a particular waist-to-hip difference. If your own difference is bigger, you will need the larger size and an alteration at the waist. If it is smaller, the larger size will gape and the smaller size may pull across the seat.

The same applies to the upper arm and sleeve. A chart that increases the bust generously while the sleeve head stays nearly the same is telling you that the arms will be tight before anything else is.

Choosing between two sizes

Work through these in order, and stop at the first one that decides it.

1. Is there a shoulder or bust fit involved? Shoulders and armscyes are the most expensive things to alter, sometimes impossible without rebuilding the garment. Buy for the shoulder and the bust.
2. Is the fabric woven with no stretch? Take the larger size, especially in anything fitted through the hip.
3. Is the fabric a knit with good recovery? Take the size that matches your bust or hip measurement most closely, without adding room for comfort.
4. Is it a structured garment meant to be worn over other clothes? Take the larger size and plan for the waist.
5. Which of the two can you fix afterwards? Waists, hems and lengths are routine alterations. Shoulders, crotch depth and the position of a bust seam are not.

One practical consequence: if the two sizes are on either side of a large jump in the chart — a common feature at the top of an extended size range — the smaller size may be genuinely too small rather than a tight fit. In that case, take the larger size and budget for a waist or a length alteration.

Before you buy

Ask the seller for flat measurements if the chart is thin: across the bust, across the waist, and the length of the garment. A shop that answers that question is usually a shop that will handle a return sensibly too.

Check the returns window and who pays return postage before you decide which size to gamble on. Where returns are free, ordering both sizes and keeping one is a legitimate method — one that most plus-size shoppers end up using at least once per new brand. Where returns are expensive, order one, treat it as calibration, and write down what you learned.

Finally, keep the chart. When an order arrives and fits, photograph the size chart and note the size you kept. Next season the same chart will be waiting, and you will be able to skip the whole process.