Fit types describe how much room a garment adds to your body and where it adds it. Slim sits closest to the body, regular follows your measurements with a small amount of ease, relaxed adds width through the chest and waist while keeping the shoulder seam near your actual shoulder, and oversized adds room everywhere including the shoulder line, which is what produces the dropped, boxy silhouette. The words describe the pattern a garment was cut from, not the size you should order.
Slim fit
Slim is the closest of the four. The pattern follows the line of the body through the chest, waist, and sleeve, with only enough ease to let you move. On a well cut slim garment the shoulder seam lands on your shoulder point or just inside it, and the side seam runs more or less straight down to the hem without flaring.
Slim is not the same as small. A slim garment in your correct size should not pull across the back or gape at the buttons. If it does, the size is wrong, not the fit type. Fabric decides how forgiving slim feels. A slim cut in a knit with stretch moves with you. The same shape in a rigid woven restricts.
Slim is also the fit most affected by build and posture. Two people with the same chest measurement can wear the same slim shirt differently depending on shoulder width. That is a limitation of the pattern.
Regular fit
Regular fit, also sold as classic fit or true to size, follows standard body measurements with a modest amount of ease built in. Seams sit where your seams sit. Nothing is deliberately added or taken away. This is the fit most people should start with when they are not sure what they want, because it is the only one of the four that does not assume a preference.

COZY's men's classic fit pants sit here. They are cut to a classic tailored fit, clean through the leg, structured without being stiff, and knit from COZY Cotton, a cotton, polyester, and spandex blend with added stretch. On a bottom, regular fit is the difference between trousers you can sit through a working day in and trousers you take off the moment you get home. It is also the easiest fit to layer over and under, which matters more in Karachi than it does anywhere with a real winter. For the measurements that separate this cut from the ones on either side of it, what classic fit means for pants takes it apart in detail.
The closest thing COZY cuts to a regular fit on top is the men's polo, which is knit in piqué and shaped for a clean, tailored line. If you are buying one, what to check before you buy a polo covers the collar and seam details worth looking at.
Relaxed fit
Relaxed adds room, but it adds it below the shoulder. Width goes into the chest, waist, and hip while the shoulder seam stays close to your actual shoulder point. The result reads easy, not exaggerated. You get space to move without changing the silhouette of the garment.

This is the fit that gets confused with oversized most often, and the shoulder is what separates them. If a product page describes extra room but says nothing about a dropped shoulder, you are almost certainly looking at a relaxed cut. COZY's Ladies Flared Pants are cut relaxed and true to size, and the ladies rugby polo is cut relaxed enough to live in while keeping a proper polo collar. On a bottom the same idea plays out as a choice between three cuts, which flared vs classic vs jogger pants sets side by side. Our guide to the ladies t-shirts COZY makes in Karachi goes through how the same distinction plays out on a tee.
Oversized fit
Oversized adds room everywhere, including the shoulder line. The shoulder seam is dropped past your actual shoulder point, the body is wider, and the whole garment reads boxy on purpose. That dropped seam is the defining feature. Without it, a garment is just large.

COZY's men's oversized t-shirt is cut to a true oversized silhouette, roomy through the shoulders and body, with dropped seams and enough structure to hold its shape. If you want the longer version, we covered the difference between relaxed fit and oversized fit separately.
How fit types survive the wash
A fit type only means something if the garment still measures the same after you have washed it. COZY makes its clothes in-house in Karachi, and the fabrics are built for that. COZY Cotton has added stretch and holds its shape wash after wash. Studio Terry is heavier and more structured, so an identical pattern reads with more weight and less cling. COZY fabrics do not shrink, as we pre-wash our fabrics beforehand.

That last point does more work than it looks like it does. A relaxed tee that tightens half a size in the wash is a regular fit by the third wear, and a regular fit that shrinks is slim. Shrinkage quietly moves a garment from the fit type you bought to one you did not.
How to check a fit before you order
Size charts describe the garment, not your body, which is why matching your usual letter size is the least reliable way to buy online. Take a piece you already own and like the fit of, lay it flat, and measure the chest width and the shoulder-to-shoulder. Compare those two numbers against the chart. They will tell you more than the length or the size label will.
For oversized pieces this is worth doing every time, because oversized patterns already add room the label does not account for. If you want to understand why fit varies so much between brands selling the same nominal size, what in-house manufacturing changes covers the production side.
Four words, four different amounts of room, and one seam that tells you which is which. Once you know where a fit type adds space, a product page stops being a guess. The Core Collection carries the fits COZY restocks year round, so you can compare a classic fit, a relaxed cut and an oversized cut side by side before you commit. Every COZY piece ships with a free string bag.