How to Find Your Bra Size at Home Without a Fitting Room

Quick answer

Measure your band size snugly around your ribcage directly under your bust, then measure your bust at the fullest point. Subtract the band measurement from the bust measurement: roughly one inch equals an A cup, two inches a B cup, three inches a C cup, and so on. Round the band to the nearest even number, then check the result against a bra you already own before you order.

A fitting room is convenient, but it is not the only place to get a reliable bra size. With a soft measuring tape, a mirror, and five quiet minutes, you can get close enough to order with confidence and fine-tune from there. The goal is not a perfect number on the first try; it is a starting point you can adjust.

This guide walks through the measurements in order, flags the mistakes that throw numbers off, and explains how to translate the result into a real bra, including styles like the Tallulah Bra and the Plunge Tallulah Bra. You will also learn how to sanity-check the size against a bra you already own, which is often more useful than the tape alone.

What you need before you start

You do not need much: a soft measuring tape, a mirror, and a bra that is not padded or molded if you have one. Wear a thin, unpadded bra or a fitted camisole so the tape can follow your body instead of the fabric. Stand in front of a mirror so you can keep the tape level.

If you do not have a soft tape, use a piece of string or a ribbon and measure it against a ruler afterward. A metal tape measure will not follow your curves accurately. Also, measure on bare skin or over thin fabric, not over a thick sweatshirt or a padded bra, because padding adds inches that will push you into the wrong cup.

• Use a soft tape, not a metal one.
• Keep the tape level all the way around.
• Measure over thin fabric, not padding.

Step 1: Measure your band size

Wrap the tape around your ribcage, directly under your bust, keeping it snug and level. Breathe out normally and let the tape sit against your skin without digging in. Write down the number in inches. If it lands on an odd number, round to the nearest even number, since most brands build bands in even sizes.

The common mistake here is pulling the tape too tight or letting it ride up at the back. Ask a mirror check: the tape should be parallel to the floor all the way around. If it slopes, the measurement will read smaller than your true band size, and you will end up with a band that feels too tight.

• Breathe out before you read the number.
• Round odd numbers to the nearest even number.
• Check in the mirror that the tape is level.

Step 2: Measure your bust size

Wrap the tape around the fullest part of your bust, usually across the nipple line. Keep the tape level and snug but not compressing. Stand straight with your arms down, and let the tape rest on your body rather than pulling it tight. Write down this number in inches.

The most common mistake is measuring over a padded or molded bra, which adds volume and inflates the cup size. Another is letting the tape dip at the back. If the tape is not level, the bust measurement will be off, and the difference between band and bust will not reflect your actual cup size.

• Measure at the fullest point, not the top of the bust.
• Keep arms down and the tape level.
• Do not compress the bust with the tape.

Step 3: Calculate your cup size

Subtract your band measurement from your bust measurement. The difference in inches gives you a rough cup size: about one inch for an A, two for a B, three for a C, four for a D, five for a DD or E, and so on. For example, a 34 band with a 37 bust is roughly a 34C.

This is the part where a bra size calculator can help, but treat it as a starting point rather than a final answer. Different brands grade cups differently, and your shape matters as much as the number. If you are between two cup sizes, start with the larger one and adjust the band if needed.

• Difference of 1 inch = roughly A cup.
• Difference of 2 inches = roughly B cup.
• Difference of 3 inches = roughly C cup.

Step 4: Check the result against a bra you own

Before you order, take a bra you already own and check the band on the loosest hook. If it rides up at the back, the band is too big; if it digs in and leaves red marks, it is too small. The center gore should sit flat against your sternum, and the cups should contain your breast tissue without spilling or gaping.

This step catches most of the errors a tape measure makes. If your calculated size is a 34C but your current 34C rides up in the back, try a 32D instead. If the cups gape but the band feels right, try a smaller cup. Use the tape as a guide, then let the fit of a real bra confirm it.

• Band should be snug on the loosest hook.
• Center gore should sit flat against the sternum.
• Cups should not spill or gape.

Step 5: Adjust for shape and style

Two people can have the same measurements and need different sizes because breast shape varies. If you are fuller on the bottom, a demi-cup like the Tallulah Bra may fit differently than a plunge style. If you are fuller on top, a plunge or lower-coverage cup can work better. The tape gives you a size; the style decides the fit.

Fabric matters too. A stretch silk charmeuse bra with a sheer mesh back will behave differently from a structured lace or molded cup. If you are between sizes, choose the style that matches your shape and adjust the band or cup from there. Do not force a size that does not suit the cut.

• Fuller on bottom: try a demi or balconette cup.
• Fuller on top: try a plunge or lower-coverage cup.
• Stretch fabrics may feel looser than structured ones.

Your at-home bra fitting checklist

1. Measure your band: Wrap a soft tape snugly under your bust, breathe out, and round odd numbers to the nearest even number. Checkpoint: the tape should be level all the way around.
2. Measure your bust: Measure at the fullest point over thin fabric, keeping the tape level and uncompressed. Mistake to avoid: measuring over a padded bra adds inches.
3. Subtract to find your cup: Band from bust gives a rough cup size: 1 inch for A, 2 for B, 3 for C, and so on. Treat a bra size calculator as a starting point, not a final answer.
4. Test against a bra you own: Check the band on the loosest hook, the center gore, and whether the cups spill or gape. If the band rides up, go down a band size and up a cup.
5. Adjust for shape and style: Match the cup style to your shape, and remember stretch fabrics may feel looser than structured ones. Next step: order one size, then adjust the band or cup if needed.

How these measurements translate to real styles

• TALLULAH BRA: Crafted from stretch silk charmeuse with a modern demi-cup silhouette, side boning, and silk-covered adjustable straps. The demi cup and side boning give structure, so if you are between cup sizes, the band and strap adjustments can fine-tune the fit more than the cup alone.
• PLUNGE TALLULAH BRA: Luxurious silk construction with a minimalist silhouette and sculpted square cups, designed to softly frame the bust. The plunge shape suits lower necklines and fuller-on-top shapes, so it is a useful alternative if a demi cup gaps at the top.

Measuring at home will not replace a professional fitting, but it gets you close enough to order with confidence. Start with the tape, confirm with a bra you own, and adjust for shape and style. If you are between sizes, choose the style that suits your shape and fine-tune from there.