You are between sizes. It is the most common problem in buying a dress online and the one that size charts answer worst, because the honest answer depends less on your measurements than on how the dress was built. Two dresses labelled the same size will fit differently if one adjusts and the other does not. This is a guide to reading that difference before you order, using nine dresses grouped by the only thing that really matters: how much the garment lets you change.
Three ways a dress handles a body
Every dress here falls into one of three groups. The first adjusts deliberately: thin adjustable straps, ties at the neck or bust, a removable waist tie. You set the fit and it stays where you put it. This group is the safest bet when you are between sizes, because the adjustment absorbs the difference.
The second adapts passively. Shirring, smocking and elasticised panels stretch across a range without any decision from you. A shirred back panel or an elasticised waistband will accommodate more variation than a seam will, and it does so quietly. The trade-off is that you cannot direct it — the dress decides where the give goes.
The third does not move at all. A bodycon cut relies on the fabric's own stretch, and a pull-on dress with no fastening has no mechanism for correction. Non-adjustable straps and fixed halternecks belong here too. These are not worse dresses; they simply move the whole decision to the moment of ordering. With this group, size down for a closer fit and up for comfort, and accept that whichever you choose is the fit you get.
What the size chart cannot tell you
A chart gives you numbers for a body. It does not tell you where the dress is tight, and that is usually the deciding question. A dress can be generous through the waist and narrow across the shoulders; a chart averages that away. Three specific things are worth checking on the product page instead.
Where the weight hangs. A halter loads everything onto the back of the neck, which some people find uncomfortable for a whole evening regardless of size. Wide fixed straps spread it across the shoulders. Thin adjustable straps let you move it.
Whether it is lined. A lined dress sits away from the body and disguises a slightly loose fit. An unlined one follows whatever is underneath, so the same size reads tighter. This is why an unlined bodycon and a lined a-line in the same size feel like different garments.
How it gets on and off. A dress that pulls on must be wide enough at its narrowest point to pass over the body, so it is rarely genuinely tight. A dress with a zip can be cut closer, because the zip solves the entry problem. That single construction fact explains a lot of surprises.
Ordering when you cannot try it on
Buying a dress you have not handled is a calculated risk, and the way to reduce it is to make the decision narrower rather than braver. Start by deciding what the dress is for. A dress you will wear for six hours at an event has a different comfort threshold from one you will wear to lunch, and the six-hour version should be the more generous choice every time. People routinely order the close fit for the long evening and regret it by the second hour.
Next, work out which part of you the dress has to clear. For most cuts here that is the bust or the hips, whichever is proportionally larger, because a dress that does not pass over the widest point cannot be worn at all regardless of how the rest sits. With an a-line or a tiered skirt, only the top half is really under discussion; the skirt will accommodate almost anything. With a bodycon, both halves are under discussion at once, which is why it is the least forgiving shape on this list.
Finally, plan for being wrong. Our returns run for 30 days from delivery on unworn items with tags attached, which is enough time to try a dress against the actual event rather than guessing in the abstract. Ordering the size you think you want, deciding properly at home, and sending back what does not work is a more reliable method than any amount of measuring, and it is the method the policy exists to support.
Group one: dresses you set yourself
The Avaline Maxi Dress has thin adjustable straps and a rubber grip inside the bust, so the top stays put without being pulled at, above ruched side detail and an open front split. It is lined, with an invisible side zip fastening on a hook and eye. Set the straps once before you leave and the dress stops asking for attention.
The Tully Maxi Dress combines both mechanisms: thin adjustable straps at the front and an elasticised shirred panel across the back. It also arrives with a removable scarf, so the dress has two versions. Between sizes, this is about as forgiving as the list gets.
Group two: dresses that adapt on their own
The Belle Maxi Dress ties closed at a square neckline, sits on thin elasticised straps and gathers into a shirred elasticised waistband, with a side invisible zip and full lining under the tiered tulle. The tie and the shirring work together, which is why it handles variation well through the middle.
The Oona Midi Dress carries a shirred panel across the back that stretches with the body, ruching at the bust and an invisible back zip. The top is lined and the skirt is not, so it reads closer below the waist than above it.
The Martin Maxi Dress ties closed at the bust, runs on an elasticised waistline and pulls on with no zip at all. Partially lined. Because it pulls on, it will not be tight anywhere it has to pass over.
The Anisa Maxi Dress in olive floral uses an elasticised waistband under a v overlay neckline fastened with a hook and eye clasp, then opens into an a-line skirt. The elastic does the accommodating; the skirt shape hides the rest.
Group three: the size is the decision
The Brissa Maxi Dress is sleeveless, pulls on, and holds a bodycon fit from bust to maxi hem with no fastening to adjust. It is lined. Nothing here corrects after the fact, so choose the size you actually want to wear.
The Hayven Midi Dress runs bodycon to midi length under a high mock neck, with gathered ruching down one side and a front split. Lined, with an invisible back zip. The ruching flatters but it does not adjust.
The Wynn Maxi Dress is one shoulder with an asymmetrical neckline, gathered ruching and a side split, cut bodycon to maxi length and lined. The single shoulder means the fit across the chest is fixed by the size and nothing else.
A note on the three shapes that behave unusually
Three cuts on this list deserve a separate warning because they surprise people. A tulle or tiered skirt, like the Belle's, adds visual volume without adding fit: it will look larger than it measures, and sizing up for the skirt is almost always a mistake. A faux wrap looks adjustable and is not, so treat it exactly as you would a fixed dress. And a one-shoulder cut, like the Wynn's, distributes all its support across a single side, which means it holds differently on different bodies in a way no chart predicts.
None of these are reasons to avoid those shapes. They are reasons to decide the size from the construction rather than from the photograph, which is the argument of this whole guide.
If you are between sizes and undecided, buy from group one. If you want the closest fit and know your size in stretch fabrics, group three will give it to you. Group two is the middle path and the one most people end up happiest with. For the earlier decisions — length and cut before any of this — see how to choose a dress by length, cut and colour.