Discover iSwim — Fit

The Same Size Does Not Mean the Same Body

Underwear has a size.

Bodies don’t.

Two people may both wear L and have similar waist measurements, yet one may have larger thighs. One may have flatter buttocks, while another has a fuller shape. Some prefer to wear their underwear higher, while others naturally position the waistband closer to the hip bones.

Even on the same person, with little change in waist measurement, differences in training, muscle development, or body proportions can make the same underwear fit completely differently.

That is why, for iSwim, size has always been only one part of fit.

The real question is:

Where does the pattern sit on the body?

Size Deals with Dimensions. The Pattern Deals with Shape.

In December 2010, iSwim established M, L, and XL as the core sizes for its underwear.

Those proportions have remained in use ever since.

Although additional sizes and adjustment options came later, we did not keep changing the fundamental proportions of the sizing system simply because the product range continued to grow.

Over time, we realized that many differences in fit cannot be solved simply by making the entire garment larger or smaller.

Fuller buttocks do not necessarily require a larger waist.

Larger thighs do not mean the front pouch needs to become larger too.

And wanting a lower rise does not mean every line should simply move downward.

Size deals with dimensions; the pattern deals with the shape of the body.

They need to be treated separately.

Rise Is Not About Moving the Entire Garment Up or Down

In 2017, iSwim established three rises: 1, 2, and 3.

In 2018, we added the higher 0.

This created the four basic rises we use today: 0, 1, 2, and 3.

But changing the rise does not mean moving the same pattern proportionally upward or downward.

If it did, lowering the waistline would also move the position where the garment actually needs to fit the buttocks. The result could easily lose its original coverage and stability.

So on June 1, 2021, iSwim further refined and standardized the relationship between the waistline and hip line across the different rises.

The waistline can change.

The hip line does not need to move proportionally with it.

This is why the same back piece can exist at different rises while still retaining its original structural characteristics.

Low-rise does not mean pulling the underwear lower.

It is a different pattern relationship in itself.

The Same Back Piece Does Not Fit Every Body Shape the Same Way

In the previous article, Evolve, we looked at Y and V.

Their central back structures are very similar, but V1 raises the angle of the side lines and uses a waistband 2 inches longer than Y1.

It may seem like a small difference.

On the body, the result can be completely different.

For flatter buttocks or more average body shapes, the lines of Y can travel naturally across the body.

But with fuller or more prominent buttocks—or after weight training changes the shape of the glutes—the original line may pass directly across the fullest part.

V does not solve this by adding more fabric.

It changes the path the lines take across the body.

They travel over the curve of the buttocks instead of working against it.

This is also how iSwim thinks about fit:

Sometimes it is not the size that needs to change. It is the position of a line.

The Front Does Not Simply Need to Be “Bigger”

The same applies to the front piece.

When people talk about space at the front of men’s underwear, size is often the first thing that comes to mind.

But over more than a decade, what we have repeatedly adjusted has never been just capacity.

NUDIST, Magic, SWAY, ROCK, and Torus cannot simply be arranged from smallest to largest.

They deal with different shapes of space, seam positions, methods of support, and freedom of movement around the leg roots.

Some bodies need more natural room to rest.

Some people have larger thighs and need less fabric around the leg roots.

Some need a deeper pouch without making the entire garment larger.

So adjustments to the front piece cannot be handled simply by “going up one size.”

Add space only where more space is needed.

Why Don’t We Let Everything Be Customized?

From 2012 to 2016, iSwim’s combination-custom designs allowed customers to freely choose different back pieces and fabrics.

That experience ultimately left us with an important answer:

Just because something can be changed does not mean it should be.

If the front piece, back piece, rise, fabric, lines, and proportions could all be changed freely, every custom order would gradually become a new pattern of its own.

And a structure that has already been repeatedly tested and refined could lose its original balance simply because one element was changed arbitrarily.

So after 2017, iSwim did not move toward a system where “everything can be customized.”

Instead, we began fixing the structures that could be reproduced consistently.

The front piece has its own structure.

The back piece has its own structure.

Rise has its own rules.

And different fabrics are suitable for different patterns.

Within those rules, we adjust the elements that actually affect how the garment fits and feels.

Semi-Custom Does Not Mean Redrawing a Pair of Underwear for You

This is the foundation of what iSwim calls semi-custom today.

Customers can adjust selected specifications within our existing pattern system according to their body shape and wearing preferences.

If more room is needed at the waist, the waistband can be adjusted.

If more space is needed at the front, the pouch depth can be adjusted.

If a different wearing height is preferred, customers can choose from our existing rise structures.

Different body shapes can also be matched with a more suitable back piece.

But there are some things we do not change.

We do not arbitrarily make a front piece or back piece narrower or wider, nor do we casually alter its original shape or proportions.

Because those lines are not decoration.

They are the pattern itself.

We don’t customize everything.
We customize what actually changes the fit.

Fit Is Not a Single Standard Answer

Some people prefer more coverage.

Some prefer the feeling of wearing almost nothing.

Someone trying a thong for the first time may still want a little familiar coverage. Someone exercising may not want to wear a thong, but still wants a back piece that does not interfere with leg movement. Others already know that they prefer Y, V, or even a structure made from a single line.

None of these preferences is more correct than another.

The purpose of a pattern is not to make every body conform to the same shape.

It is to help different bodies find structures that work for them.

From a single pair of swimwear in 2009, to NUDIST, different front pieces, back pieces, four rises, and today’s semi-custom system, iSwim has spent more than a decade working on essentially the same thing:

Let the pattern follow the body, rather than making the body adapt to the pattern.

This is also where all three Discover iSwim stories ultimately come together.

Because what we have really been trying to create was never simply more styles.

It was a better fit.

Read again: Discover iSwim — Start