Quick Answer: A hem rides higher wherever the fabric has to travel further to get around your body. Fuller hips and thighs consume vertical fabric length as the dress passes over them, so the hem lifts at the widest point and drops where the body is narrower. It is a pattern problem, not a sizing problem - going up a size adds width everywhere and usually makes the hem worse, not better. The real fixes are a size with more hip room, a fabric with give, an A-line rather than a straight cut, or a proper hem levelling by a tailor.

On the hanger the hem was a straight line. In the mirror it dips at the back and lifts at the sides.

And every time you go up a size the dress gets baggier and the hem does exactly the same thing.

Why does the hem lift at the hip specifically?

Fabric travelling over a curve uses length. A dress passing over a fuller hip has to cover more distance, and it takes that distance from the vertical - which is the hem.

The effect is proportional to the curve. A more pronounced hip takes more length, which is why this appears on some bodies and not others in the identical dress.

Straight-cut dresses show it most, since there is no extra fabric width designed in to absorb the travel.

Stretch fabrics show it differently but do not remove it. They stretch horizontally to accommodate the hip, which pulls the vertical up in the same way and often adds visible horizontal tension lines.

A fuller seat produces the same effect at the back, which is why the back hem often sits shorter than the front.

And commercial patterns are drafted to a standard hip-to-waist ratio that does not describe a great many bodies, which is the root of the whole thing.

Why does sizing up not fix it?

Because a size adds width everywhere at once. You get the hip room you needed, plus shoulder, bust and waist room you did not.

The hem problem is caused by the ratio, not the circumference, so scaling the whole garment up preserves the ratio that caused it.

A larger size adds a little length in most grading rules, but rarely enough at the hip to level the hem, and it introduces a loose bodice.

A loose bodice makes it look worse, not better, because a dress that hangs from the shoulders without any waist definition emphasises the uneven hem rather than disguising it.

Two sizes up is where people usually end up, with a dress that is right at the hip and visibly wrong everywhere above it.

Which is why the answer is a different cut or an alteration rather than a different number.

Which dress shapes actually solve it?

A-line is the most reliable answer, because the extra width designed into the skirt gives the fabric somewhere to travel without borrowing from the length.

Fit-and-flare works for the same reason, with the flare beginning above the fullest point.

Bias-cut dresses handle curves genuinely well, since fabric cut on the diagonal has natural give in every direction. The trade is that bias hems need professional levelling and time to hang.

Wrap dresses are good at the waist and hip and separate the bodice fit from the skirt fit, which removes the sizing compromise entirely.

Straight and column shapes are the hardest, and they need either substantial stretch or an alteration.

And a skirt with any gathering or pleating at the waist hides the whole issue, because a gathered hem is not read as a straight line in the first place.

What can a tailor actually do?

Level the hem, which is the direct fix and it is straightforward. The tailor pins it on you rather than flat, and takes more length where the fabric has ridden up.

It costs modestly and takes little time, and it is by some distance the most under-used alteration in most wardrobes.

It requires enough hem allowance, so check the inside of the hem before buying - a deep hem gives options and a narrow overlocked one gives almost none.

Adding side panels or letting out side seams creates hip room if the seam allowance exists, and it addresses the cause rather than the symptom.

Taking in the bodice on a size-up dress is the standard route and often the cheapest way to make a too-large dress correct.

And for a favourite dress it is always worth it. A levelled hem on a dress you love changes it from nearly-right to right, which is a better use of money than another nearly-right dress.

How do you check for this in a fitting room?

Look at the hem in the mirror rather than at the whole outfit, since a hem line is easy to see once you are specifically looking for it.

Turn side-on and check the back, which is where a fuller seat produces the shortest hem and where you cannot see it face-on.

Look for horizontal pull lines at the hip, which tell you the fabric is under tension and will ride further as you move.

Walk a few steps and check again, since movement makes a marginal problem obvious.

Sit down and stand up before deciding, because a hem that rides on sitting and does not fully return is a hem that will spend the evening in the wrong place.

And check the hem allowance inside before you buy anything you intend to have altered.

FAQ: Dress Hem and Fit Questions, Answered

Is an uneven hem a fault in the dress?

No, it is a mismatch between a standard pattern ratio and your proportions. The dress is made correctly for a body shape that is not yours.

Should I size up for fuller hips?

Generally no. Sizing up adds width everywhere and keeps the ratio that caused the problem. A different cut or an alteration works better.

How much does hem levelling cost?

Modest - it is one of the cheaper alterations, and it is priced by hem length rather than by complexity.

Which dress shape is safest?

A-line or fit-and-flare, with the flare starting above the fullest point. Both give the fabric room to travel without taking it from the length.

Do stretch fabrics solve it?

They disguise it and can introduce visible horizontal tension lines instead. They do not remove the underlying cause.

What should I check before buying a dress to alter?

The depth of the hem allowance inside the garment. A deep hem gives a tailor room to work; a narrow overlocked edge gives almost none.

TL;DR:

• A hem lifts wherever fabric has to travel further around the body - fuller hips and seat take that length from the vertical.
• It is a pattern ratio problem, not a size problem, which is why sizing up makes the bodice loose and the hem no better.
• A-line, fit-and-flare, bias and wrap shapes all give the fabric somewhere to travel.
• Hem levelling by a tailor is cheap, quick and the most under-used alteration there is.
• Check the hem allowance inside before buying anything you plan to have altered.

The dress is not wrong and neither are you. The pattern was drafted for a different ratio.