the bra size calculator

A LITTLE GUIDANCE. LESS GUESSWORK.

How to Measure Your Bra Size

A soft tape, a comfortable position, and a few careful readings.

You can start with two measurements or choose six for additional posture and band-tension information. The methods use different measuring conditions. Pick one method and follow its instructions from the start.

Before you measure

  • Use a flexible measuring tape with easy-to-read markings. A mirror can help you check the tape across your back.
  • Choose inches or centimeters and record the actual reading. Let the calculator handle conversions and rounding.
  • Stand relaxed rather than holding your chest up or sucking in. Underbust measurements should stay at the same height around the torso.
  • Keep your measurements private. You do not need photos, an account or an upload to use this tool.

The quick method: underbust and bust

For our two-measurement estimate, wear a non-padded bra. Avoid a padded or push-up bra that substantially changes the outline you are measuring.

1. Measure your underbust

Same position · comfortably snugWear a non-padded bra. Pull comfortably snug, as you would want a band to feel.
Same position · comfortably snug

Place the tape just below your breasts. Keep it snug and horizontal all the way around. Write down the reading without rounding it first.

2. Measure your bust

Stand upright · tape levelWear a non-padded bra. Stand upright with relaxed shoulders. Keep the tape level.
Stand upright · tape level

Wrap the tape around the fullest part over the non-padded bra. Let it rest gently against the fabric without flattening your breasts. Keep it level across your back.

For this quick method, measure in a non-padded bra. The six-measurement method below is taken without a bra. The illustrations demonstrate tape positions and postures, not a reconstruction of your body.

Enter both readings in the quick calculator. Prefer to work through it yourself? See the band and cup size chart.

The optional six-measurement method

This adds three levels of underbust tension and three bust postures. It can provide extra context when a single standing measurement feels incomplete. More readings do not guarantee a more accurate fit.

Start fresh without a bra. Do not copy the bra-supported readings from the quick method. The bra shown in the illustrations is for teaching the position; it does not show unsupported breast shape. If a posture is uncomfortable or inaccessible, use the quick option instead.

MEASUREMENT 1 OF 6

Loose underbust

Stand upright and wrap the tape just below your breasts. Let it make light contact, without pulling it into the skin. Keep this tape position for all three underbust readings.

Same position · light contactLet the tape just touch your skin, without digging in. The bra helps identify the lower edge of the breasts. Measure without a bra; keep the tape in the same place for all three readings, changing only the tension.
Same position · light contact

MEASUREMENT 2 OF 6

Snug underbust

At the same position, pull the tape comfortably snug—how you would want a supportive band to feel. Keep your shoulders relaxed and the tape level around your back.

Same position · comfortably snugPull comfortably snug, as you would want a band to feel. The bra helps identify the lower edge of the breasts. Measure without a bra; keep the tape in the same place for all three readings, changing only the tension.
Same position · comfortably snug

MEASUREMENT 3 OF 6

Tight underbust

Breathe out and take a firm reading in the same place. Do not pull to the point of pain. This reading provides context for band comfort; it is not the band you must wear.

Same position · exhale, then tightenBreathe out and pull the tape firmly, without causing pain. The bra helps identify the lower edge of the breasts. Measure without a bra; keep the tape in the same place for all three readings, changing only the tension.
Same position · exhale, then tighten

MEASUREMENT 4 OF 6

Standing bust

Stand upright without a bra. Bring the tape around the fullest part of your breasts with gentle contact. Do not push tissue inward or lift it to meet the tape.

Stand upright · tape levelStand upright with relaxed shoulders. Keep the tape level. The bra is shown for the posture demonstration, not to represent unsupported breast shape. Orange markers indicate the measurement area. Measure without a bra, around the fullest part without compressing.
Stand upright · tape level

MEASUREMENT 5 OF 6

Leaning bust

Bend forward about 90 degrees and let the breasts hang naturally. Wrap the tape around the fullest part, keeping it perpendicular to your torso. Do not squeeze tissue together.

Lean 90° · measure the fullest partBend forward about 90°, with your back parallel to the floor. The bra is shown for the posture demonstration, not to represent unsupported breast shape. Orange markers indicate the measurement area. Measure without a bra, around the fullest part without compressing.
Lean 90° · measure the fullest part

MEASUREMENT 6 OF 6

Lying bust

Lie on your back and allow tissue to settle naturally. Measure around the fullest part without gathering it together. Keep the tape in contact rather than pulling it tight.

Lie on your back · let tissue settleLie on your back. Measure around the tissue where it naturally falls. A mirror can help check the tape. The bra is shown for the posture demonstration, not to represent unsupported breast shape. Orange markers indicate the measurement area. Measure without a bra, around the fullest part without compressing.
Lie on your back · let tissue settle

Try the six-measurement calculator →

Our detailed method is an independent implementation of the A Bra That Fits community manual, with explicit software rules and limits. It may differ from their online calculator. Read our calculation method for the differences.

Before you use the result, recheck these things

  • Tape position: a tilted tape or a different underbust height can change the reading.
  • Tension: bust measurements use gentle contact. Only the underbust readings ask you to vary tension.
  • Units: make sure every number is in the selected unit. Do not enter inches while the tool is set to centimeters.
  • Order: loose underbust should be at least as large as snug, and snug at least as large as tight. Remeasure if the order is reversed.
  • Small differences: a reading near a rounding boundary can change a letter or band. Keep the original readings and compare actual fit rather than chasing a single perfect number.

Measuring questions

Should I wear a bra when measuring?

Follow the specific method. Our quick estimate uses a non-padded bra; our detailed six-measurement method uses no bra. Different measuring protocols should not be mixed.

What if my breasts are different sizes?

A circumference reading cannot fully describe the difference. When trying a bra, check that the cup on the fuller side does not compress or spill, and check the whole bra for comfort. The calculator does not prescribe an automatic extra cup size.

Can I get the perfect bra size from measurements alone?

No measurement method can guarantee the fit of a particular bra. Construction, shape and comfort matter. After calculating, use the band, cup and wire checks to decide what to try next.

Quick method reference: BRABAR fit guide. Practical fitting reference: Bravissimo fitting guide.

Method and references reviewed September 29, 2026. Read our methods and limits.