Three lengths, and the few inches between them change the shoe, the proportion and the room the skirt belongs in.
A skirt is defined more by where it ends than by anything else about it. Two skirts in the same fabric and the same cut, one ending above the knee and one at the calf, are not variations on a theme. They are different garments, worn with different shoes, to different places.
There are three lengths worth knowing, and one rule inside the middle one that matters more than all the rest.
Mini
Anything ending above the knee. The most leg, the most casual by default, and the length most dependent on what else is happening in the outfit.
A mini balances best with coverage on top: a long sleeve, a higher neck, or a looser shape. A fitted mini with a fitted top reads as a single tight line, and most people find it harder to wear than they expect.
It also changes completely with legwear. Bare legs and a flat shoe is summer. Opaque tights and a boot is the same skirt in January.
Midi, and the Calf Rule
The useful length and the one that goes wrong most often. A midi ends somewhere between the knee and the ankle, and within that range there is a narrow band that works and a wider band that does not.
The rule: the hem should end at the narrowest part of your lower leg. For most people that is just below the widest point of the calf, or right at the ankle. A hem that stops at the widest part of the calf cuts the leg at its broadest and makes the whole silhouette heavier.
This is not about body shape. It is about where a horizontal line falls on a tapering shape, and it is why the same midi skirt looks right on one person and wrong on another who is two inches taller.
If a midi lands badly, the fix is a heel, which moves your calf down relative to the hem, or a hem alteration, which is cheap on a straight skirt.
Midi length follows exactly the same logic in a dress.
Maxi
Ending at the ankle or the floor. The dressiest length and, counterintuitively, one of the easiest, because there is no hem line cutting the leg at all. The silhouette runs uninterrupted from waist to floor.
The one thing a maxi needs is to clear the ground. Half an inch above the floor in the shoe you will wear. Longer and it drags and frays; much shorter and it reads as a midi that missed.
A maxi in a heavy fabric reads formal. The same length in cotton or jersey reads relaxed, which is why a maxi can be both a beach skirt and an evening skirt.
The Shape Underneath the Length
Length sets the register; cut sets the mood.
Straight. Clean and sharp at any length. The most formal cut.
A-line. Widening steadily to the hem. Easy at every length and the most forgiving over the hip. The A-line behaves the same way in a dress.
Pleated. Movement built in. Reads classic in a midi and school uniform in a mini, so length matters here more than elsewhere.
Bias cut. Cut on the diagonal so the fabric skims. Beautiful in a midi or maxi, and it shows every line underneath.
The hem should land at the narrowest part of your lower leg. Two inches higher, at the widest part of the calf, and the whole silhouette gets heavier.
The Shoe Each Length Asks For
Mini. Almost anything. A flat works because the leg is already long in the frame. A boot works. This is the most flexible length for footwear.
Midi. The hardest, and the reason most midi skirts sit unworn. A heel of any height helps, because it lengthens the leg below the hem. A flat works only if the hem is at the ankle rather than mid calf, or if the shoe is visually substantial, like a boot that fills the gap.
Maxi. A heel if the skirt is long enough to need one, a flat if it is cut for it. The thing to avoid is a delicate shoe disappearing entirely under the hem.
The gap between hem and shoe is what people notice without being able to name. A small gap of bare ankle reads deliberate. A large gap of bare shin reads unplanned.
Waist Height
Where a skirt sits matters almost as much as where it ends.
High waist. At or above the natural waist. Lengthens the leg and gives a clear place to tuck. The most useful for a midi.
Mid. Just below the waist. Comfortable and neutral.
Low. On the hip. Shortens the visible leg and makes the hem land lower than the size chart implies.
Three Outfits
Work. Straight midi, high waist, a tucked blouse, a closed heel. A blazer if the room is formal.
Weekend. A-line mini, opaque tights, flat boot, an oversized knit half tucked.
Evening. Bias maxi, a fitted top, and nothing else competing.
What to Check
The lining length. A lining that stops short of the hem is visible in daylight on anything light.
The vent. A straight midi needs a slit or a vent or you cannot walk properly. Take four full steps in the fitting room.
Where the waistband sits when you sit. A high waisted skirt that gapes at the back when seated is cut for a straighter back than yours, and a tailor can take it in at the center seam for very little.
Skirts Worth Knowing
Common Questions
How to Dress a Sequin Mini Skirt?
Treat the skirt as the whole outfit and keep everything else quiet. A plain knit or a simple long sleeve top on top, tucked so the waistband shows, then opaque tights and a boot if it is cold or bare legs and a heel if it is not. The top half wants coverage, because a sequin mini and a bare top half together read as costume. One piece of jewelry, a plain bag, and nothing else with texture.
Can Plus Size Wear Midi Skirt?
Yes, and the calf rule is the thing worth knowing rather than any rule about size. A midi works when the hem lands at the narrowest part of your lower leg and looks heavier when it stops at the widest part of the calf, and that is true at every size. A high waist helps, because it sets a clear line and lengthens the leg below it. If a skirt you like lands badly, a heel moves the calf down relative to the hem, and shortening a straight skirt is an inexpensive alteration.
The Short Version
Pick the length first, because it decides the shoe and the setting. For a midi, check where the hem falls against your calf before anything else, and remember a heel or a quick alteration fixes a hem that lands wrong. Go high waisted if you plan to tuck. And in a straight skirt, walk four steps before you buy it.