How to Measure Binder Size FTM: Getting the Right Fit?

Binder sizing ignores bra and T-shirt sizes entirely — measure the fullest part of your chest with a soft tape and match that number to the specific brand’s own chart.

A tape pulled one inch too tight can drop you a whole size, and sizing down to flatten more is the mistake safety guides warn about most. Get the number right the first time and you skip the exchange and the return shipping.

Binder sizing is not universal. Different manufacturers — and even different models from the same brand — size differently, so the only measurement that counts is the one you take against that brand’s chart.

What You Need Before You Measure

You need a soft measuring tape and a mirror. String works if you don’t have a tape — mark it, then measure against a ruler.

Two prep details decide accuracy. Wear what you’d normally wear underneath a binder, not a padded or compression garment, since those add phantom inches. And measure while standing naturally, breathing normally — sucking in or flexing changes the number you’ll be stuck with for the life of the binder.

How to Measure Your Chest Step by Step

Measure around the fullest part of your chest, keeping the tape level all the way around and snug — flat against the skin, not digging in.

1. Wrap the tape around the fullest part of your chest, usually across the nipple line.
2. Check in a mirror that the tape is level — not riding up in back or dipping in front.
3. Breathe out normally and let the tape sit snug. If you can slide two fingers under it, that’s about right; if it leaves a red mark, it’s too tight.
4. Write the number down in inches. Some brands also ask for your underbust or rib cage and shoulder width — check that brand’s guide first so you only measure once.
5. Measure twice. If the numbers differ, take the larger one.

Which Measurement Does Each Brand Want?

Most brands want the full chest measurement, but some also require underbust and shoulder width — so read the specific chart before you buy. Chest is the near-universal starting point. Underbust or rib cage captures how much room your ribcage needs when you breathe. Shoulder width decides whether the straps sit where they should.

Kaiser Permanente’s chest-binding chart uses chest measurement in inches:

This chart is one example, not a universal standard — a 38-inch chest fits a medium here, but another brand’s medium may top out at 37 inches. Always confirm against the chart on the page you’re buying from, per Kaiser Permanente’s chest-binding guidance.

Between Sizes, and How to Tell the Fit Is Right

If your measurement lands between two sizes, go up. That rule shows up across every sizing guide: a slightly loose binder still compresses, while one that’s too small restricts breathing.

Fit checks once it arrives:

• You can take a full, deep breath without fighting the fabric.
• You can raise your arms and rotate your upper body freely.
• It feels snug against your chest, not tight or pinching.
• No skin is caught or pinched at the edges or under the arms.

Any pain, tingling, numbness, trouble breathing, or a binder so tight you struggle to get it on means it’s too small. Stop wearing it — don’t try to break it in. Before ordering from a new brand or style, remeasure from scratch rather than reusing your old number, since sizing shifts between manufacturers and models.

If you measure above the standard range or fall between sizes at the top end, made-to-measure binders exist, and some retailers carry sizes up to 5X. If you’re unsure which style to order, this guide to the best FTM binders for everyday wear can help.

The short version: measure the fullest part of your chest with a soft tape, keep it level and snug, check the brand’s own chart, and size up when you’re between numbers. The number matters more than the label. TransHub’s binding guide and UC Santa Barbara’s “How to Buy a Binder” both land on the same rule.