Power Calculators

👙 Bra Size Calculator

Calculate an estimated bra band and cup size from your underbust and bust measurements using meters, centimeters, inches or feet.

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Enter details

Choose the unit you will use for all measurements.
Measure snugly around your ribcage directly under the breasts.
Measure around the fullest part of your bust without compressing the breasts.
Underbust (cm)
81.28
Bust (cm)
93.98
US/UK Band Number
32
EU Band Number
80
Bust-to-Band Difference (inches)
5
Bust-to-Band Difference (cm)
12.7
Cup Size Index - 0=AA, 1=A, 2=B, 3=C, 4=D, 5=DD/E, 6=DDD/F, 7=G, 8=H, 9=I, 10=J, 11=K, 12=L/HH, 13=M/J, 14=N/JJ
5

Also available in our Android app, with charts and full breakdown tables.

📘 About the Bra Size

This bra size calculator estimates a bra band and cup size from two measurements: underbust and bust.

You can enter measurements in meters, centimeters, inches or feet. Both measurements must use the selected unit.

Bra sizing is not globally standardized. US, UK and EU systems use different band and cup conventions, and individual brands can also fit differently.

✏️ Worked examples

Example 1 - Centimeters

You enter
Measurement UnitCentimeters (cm)
Underbust Measurement76
Bust Measurement91
You get
Underbust (cm)76
Bust (cm)91
US/UK Band Number30
EU Band Number75
Bust-to-Band Difference (inches)5.82677
Bust-to-Band Difference (cm)14.8
Cup Size Index - 0=AA, 1=A, 2=B, 3=C, 4=D, 5=DD/E, 6=DDD/F, 7=G, 8=H, 9=I, 10=J, 11=K, 12=L/HH, 13=M/J, 14=N/JJ6

Enter a 76 cm underbust and a 91 cm bust.

Try this example →

Example 2 - Inches

You enter
Measurement UnitInches (in)
Underbust Measurement32
Bust Measurement37
You get
Underbust (cm)81.28
Bust (cm)93.98
US/UK Band Number32
EU Band Number80
Bust-to-Band Difference (inches)5
Bust-to-Band Difference (cm)12.7
Cup Size Index - 0=AA, 1=A, 2=B, 3=C, 4=D, 5=DD/E, 6=DDD/F, 7=G, 8=H, 9=I, 10=J, 11=K, 12=L/HH, 13=M/J, 14=N/JJ5

Enter a 32 inch underbust and a 37 inch bust.

Try this example →

Example 3 - Meters

You enter
Measurement UnitMeters (m)
Underbust Measurement0.80
Bust Measurement0.95
You get
Underbust (cm)80
Bust (cm)95
US/UK Band Number32
EU Band Number80
Bust-to-Band Difference (inches)5.40157
Bust-to-Band Difference (cm)13.72
Cup Size Index - 0=AA, 1=A, 2=B, 3=C, 4=D, 5=DD/E, 6=DDD/F, 7=G, 8=H, 9=I, 10=J, 11=K, 12=L/HH, 13=M/J, 14=N/JJ5

Enter an 0.80 m underbust and a 0.95 m bust.

Try this example →

🧭 How to use this calculator

What you enter

  • Measurement UnitChoose the unit you will use for all measurements.
  • Underbust MeasurementMeasure snugly around your ribcage directly under the breasts.
  • Bust MeasurementMeasure around the fullest part of your bust without compressing the breasts.

What you get

  • Underbust (cm)
  • Bust (cm)
  • US/UK Band Number
  • EU Band Number
  • Bust-to-Band Difference (inches)
  • Bust-to-Band Difference (cm)
  • Cup Size Index - 0=AA, 1=A, 2=B, 3=C, 4=D, 5=DD/E, 6=DDD/F, 7=G, 8=H, 9=I, 10=J, 11=K, 12=L/HH, 13=M/J, 14=N/JJ

💡 How the bra size is calculated

  • Your selected measurement unit is first converted to centimeters and inches.
  • The underbust measurement is used to estimate the band size.
  • The difference between bust and band measurements is used to estimate the cup size.
  • The result provides US/UK band guidance and an EU band reference.
  • Cup naming can differ between US and UK systems, so always compare the result with the brand size chart.

💡 How to measure your underbust

  • Use a flexible measuring tape.
  • Measure directly underneath the breasts around the ribcage.
  • Keep the tape horizontal around your body.
  • Keep the tape snug but do not pull it painfully tight.
  • Take the measurement while standing naturally.

💡 How to measure your bust

  • Measure around the fullest part of the breasts.
  • Keep the tape horizontal around the body.
  • Do not compress the breast tissue.
  • Wear a non-padded or lightly lined bra when possible.
  • Take the measurement without changing your normal posture.

💡 Bra size mapping

  • Cup index 0 = AA.
  • Cup index 1 = A.
  • Cup index 2 = B.
  • Cup index 3 = C.
  • Cup index 4 = D.
  • Cup index 5 = DD or E depending on the sizing system.
  • Cup index 6 = DDD or F depending on the sizing system.
  • Higher cup indices continue to use different country and brand naming systems.
  • Always use the manufacturers own size chart when buying a specific bra.

💡 Important sizing limitation

  • Bra sizes are not universal between countries.
  • US and UK cup naming becomes increasingly different at larger cup sizes.
  • Different brands can use different grading and fit patterns.
  • Bra style, underwire shape, padding, stretch and breast shape can change the best fitting size.
  • This calculator should therefore be treated as an estimated measurement-based starting point.

❓ Frequently asked questions

Can I enter measurements in meters?

Yes. Select meters and enter both the underbust and bust measurements in meters.

Can I enter measurements in centimeters?

Yes. Centimeters are supported and are commonly used for body measurements.

Can I enter measurements in inches?

Yes. Select inches and enter both measurements in inches.

Can I enter measurements in feet?

Yes. Select feet and enter both measurements in feet.

Is the calculated bra size guaranteed to fit?

No. Bra sizing varies between brands, countries and bra styles. Use the result as a starting point and compare your measurements with the manufacturers size chart.

Why can two brands give me different bra sizes?

Brands can use different band measurements, cup grading, materials and garment construction. The same body measurements can therefore correspond to different labeled sizes.

Should I measure over a padded bra?

A non-padded or lightly lined bra generally gives a more useful measurement for a measurement-based calculator.