Finding your bra size at home is easier than you might expect. You only need a measuring tape, a mirror and a few quiet minutes.
However, your measurements will not reveal one guaranteed bra size. They provide a sensible starting point for trying different bras.
Every brand uses slightly different patterns, fabrics and sizing systems. Individual styles can also fit differently within the same brand.
Breast shape, tissue softness and personal comfort also affect fit. Therefore, treat your calculated size as the beginning of the fitting process. After measuring, always check how the bra fits your body.
Try to measure when your breasts feel close to their usual size. Hormonal changes can temporarily affect breast volume and tenderness. Pregnancy, breastfeeding and weight changes can also alter your measurements. Measure again whenever your usual bras begin feeling different.
Choose a private space where you can move comfortably. Stand near a mirror with enough room to turn around. The mirror helps you check the measuring tape from every angle. It should remain straight and level around your body.
You can also ask someone you trust to help. A helper may make checking the back of the tape easier. However, measuring alone is perfectly possible.
Gather everything before removing your clothing.
You will need:
Avoid using a metal building tape measure. It will not follow your body’s curves correctly. A fabric sewing tape works much better.
Check that the tape has not stretched or become damaged. You should also confirm whether it displays centimetres or inches. Australian bra sizing guides usually use centimetres.
You can measure without a bra or wear a non-padded bra. The best choice depends on your breast shape and comfort.
Measuring without a bra avoids padding changing your bust measurement. However, softer or lower-set breasts may be harder to measure while standing.
A supportive, non-padded bra can gently hold the breasts in position. Choose a bra without thick foam, push-up padding or heavy compression. The bra should not flatten or enlarge your natural breast shape. Avoid measuring in a sports bra.
Compression sports bras can reduce the fullest bust measurement. Also avoid measuring in a heavily padded T-shirt bra. Padding may add several centimetres around the bust.
Measure against bare skin whenever possible. You can also wear a thin, close-fitting top. Avoid jumpers, jackets or loose clothing.
Thick fabric can increase both measurements. Loose fabric can also make tape placement difficult. Even small measurement changes may affect the suggested starting size.
You will take at least two measurements:
Write every measurement down immediately. Do not rely on remembering several similar numbers.
Measure each position twice for accuracy. Repeat the measurement when the two results differ noticeably.
Your underbust measurement helps estimate your starting band size. This measurement is taken around your ribcage. It should sit directly beneath your breast tissue.
Position the Tape Correctly
Lift each breast gently if necessary. Place the tape directly beneath the breast root. The breast root is where breast tissue meets your chest.
The tape should not sit across breast tissue. It should also not sit several centimetres below the breasts.
Wrap the tape around your ribcage. Check its position in the mirror. The tape should form one straight horizontal line. It should remain parallel with the floor.
Take a Comfortable Underbust Measurement
First, hold the tape comfortably against your skin. It should touch your body without hanging loosely.
Take a normal breath. Then breathe out naturally. Do not suck in your stomach. Do not hold your breath.
Read the measurement where the tape meets. Record the number in centimetres. Label it “comfortable underbust.”
Take a Firm Underbust Measurement
Now pull the tape slightly firmer. The tape should feel secure around your ribcage. It should not feel painful or restrictive. You should still breathe normally. Record this second number. Label it “firm underbust.”
The difference between these measurements provides useful information. A softer ribcage area may compress more under a firm bra band. A firmer ribcage may show very little difference.
How Tight Should the Tape Feel?
Think about the secure feeling of a supportive bra band. The tape should feel firm but not painful. It should not leave deep marks. It should not make breathing difficult. You should not pull until the tape cuts into your skin.
A painfully tight measurement will suggest an unnecessarily small band. A very loose measurement may suggest an unsupportive band.
Check the Back of the Tape
Turn sideways while looking into the mirror. Then check the back.
The tape often drifts downward without the wearer noticing. It can also rise toward the shoulder blades. Both positions can change the result.
Ask a helper to correct the tape when necessary. Otherwise, adjust it while watching your reflection.
Correct underbust tape placement
Incorrect underbust tape placement
The over-bust measurement estimates your cup volume. Measure around the fullest part of your breasts.
This point often crosses the nipples. However, it may sit slightly higher or lower. Breast shape determines the exact fullest position.
Find the Fullest Breast Area
Stand naturally with your arms relaxed. Look at your side profile in the mirror. Identify the fullest point of your breasts.
Pass the tape around this area. Do not automatically place it at a fixed height.
The fullest point differs between bodies. It may also differ between breasts. When one breast is larger, measure around the fullest overall position.
Keep the Tape Relaxed
Allow the tape to rest gently against your breasts. It should not squeeze or flatten breast tissue. It should not hang away from the body. You should be able to slide one finger beneath it.
Keep your shoulders relaxed. Do not push your chest forward. Do not pull your shoulders backwards. Stand in your normal posture.
Keep the Tape Parallel With the Floor
Check the tape in the mirror. Look at the front, side and back. It should remain horizontal around your body. A sloping tape produces an unreliable measurement.
This is particularly common with fuller or lower-set breasts. Adjust the back until it matches the front height. A helper can make this step easier.
Record the Over-Bust Measurement
Breathe normally. Read the measurement without pulling the tape tighter. Round only when necessary.
Record the number to the nearest half-centimetre. Measure again. Use the repeated result when both numbers are similar.
Correct over-bust placement
Incorrect over-bust placement
The tape sits above the fullest area.
Australian band sizes use even clothing-style numbers. Common sizes include 8, 10, 12, 14 and 16.
Each band generally covers an underbust range of about five centimetres. For example, 68–72 centimetres commonly corresponds with an Australian size 10. A 73–77 centimetre underbust commonly corresponds with size 12.
Use this table as general guidance:
Underbust measurement | Suggested Australian band |
63–67 cm | 8 |
68–72 cm | 10 |
73–77 cm | 12 |
78–82 cm | 14 |
83–87 cm | 16 |
88–92 cm | 18 |
93–97 cm | 20 |
98–102 cm | 22 |
103–107 cm | 24 |
108–112 cm | 26 |
These ranges provide a starting point only. Band stretch differs between brands and styles.
A firm sports bra may feel smaller than a soft everyday bra. Some people also prefer a firmer or gentler band. Choose the band that remains secure without causing pain.
Cup size is based on the relationship between two measurements. These are your bust and underbust measurements. A larger difference usually suggests a larger cup.
However, cup calculations vary between sizing systems and brands. Australian retailers often use a fitting chart or calculator. This avoids relying on one universal subtraction formula.
Enter your measurements into our Bra Size Calculator. The calculator will estimate your band and cup together.
Cup Letters Are Relative to Band Size
A cup letter does not represent one fixed breast volume. A 10D has less cup volume than a 16D. Both bras carry a D cup label.
However, their cup dimensions are not identical. Cup volume increases as band size increases.
This is why cup letters must always appear with band sizes. Saying “I am a D cup” only gives part of the size. The full size might be 10D, 14D or 18D. Each one represents a different volume.
Why We Recommend the Calculator
Manual cup charts can become confusing. Australian, UK, US and European cup letters differ.
Some brands use double letters. Others move directly to the next single letter.
Sports Bras Direct stocks brands from several countries. Our calculator should present an Australian starting size first. Product pages can then show the correct brand conversion.
A calculator cannot see your breast shape. It cannot assess your breast roots or spacing.
It also cannot feel the fabric’s firmness. Two bras carrying the same size can fit differently. One may have wide and shallow cups. Another may have narrow and deep cups.
Your measurements can suit both size labels. Yet only one design may suit your shape.
This does not mean your body is difficult. It means bra sizing describes volume imperfectly. That is why every calculated result needs a fit check.
Small errors can change the suggested size. Check these common mistakes before using your results.
Measuring Over Thick Clothing
Jumpers, shirts and layered clothing add bulk. They also hide the tape’s position. Measure against bare skin when possible. A thin, fitted top is the next best choice.
Wearing a Padded Bra
Padding increases the bust circumference. Push-up padding can also move breast tissue upward. Choose a non-padded bra or measure without one. Avoid compression sports bras too.
Letting the Tape Slope Down
A downward-sloping tape creates a larger circumference. This mistake often happens behind the body. Use the mirror to check all sides. The tape should remain parallel with the floor.
Pulling the Bust Tape Too Tight
The bust measurement should not flatten breast tissue. Compression can reduce the result. This may suggest cups that are too small. Let the tape rest gently against the breasts.
Measuring the Underbust Too Loosely
A loose measurement may suggest an oversized band. The band then provides less support. Take both comfortable and firm measurements. Use them together when choosing a starting band.
Pulling the Underbust Painfully Tight
Support should not require painful pressure. An extremely tight measurement may suggest a restrictive band. You must still breathe comfortably. The tape should feel firm, not punishing.
Holding Your Breath
Holding your breath changes your ribcage measurement. It also creates an unrealistic result. Breathe normally throughout the process. Take the reading after a natural exhale.
Measuring Only Once
Tapes move easily. Posture also changes between attempts. Take every measurement at least twice. Repeat any result that differs noticeably.
Assuming Clothing Size Equals Bra Band Size
Your dress size does not determine your bra band. Both systems use similar Australian numbers. However, they measure different areas. Always use your underbust measurement.
Using an Old Bra as Your Size Standard
Old bras stretch gradually. You may not notice support reducing. A familiar bra can feel comfortable while fitting poorly. Measure again before replacing very old bras.
Assuming Every Brand Fits Identically
Bra sizing is not perfectly standardised. Band stretch and cup shape vary. Always read brand-specific fit advice. Check product-specific guidance whenever available.
Measuring Only During One Life Stage
Breast size changes over time. Pregnancy, breastfeeding and menopause may affect fit. Weight changes can alter band and cup measurements. Hormonal changes may cause temporary fluctuation. Measure again whenever your bras feel different.
Your numbers are ready. Now turn them into a practical fitting result.
Use the Bra Size Calculator
Enter your underbust and bust measurements. Include extra measurements when the calculator accepts them. Review the suggested Australian starting size. Note any nearby sizes provided. Use our Bra Size Calculator.
Try the Suggested Size
Start with the recommended size. Choose an adjustable bra with clearly defined cups. Fasten a new bra on its loosest comfortable hook. Scoop all breast tissue into the cups.
Then adjust each strap. Do not judge the fit before positioning the bra correctly.
Try Nearby Sister Sizes
A sister size has similar cup volume. However, it uses a different band size. For example, moving up one band usually requires a smaller cup letter. Moving down one band usually requires a larger cup letter. Sister sizing may improve band comfort. However, it can also change wire width and strap placement.
Use our Bra Sister Size Chart for guidance.
Complete the Six-Point Fit Check
Check these six areas:
The band should remain level. The cups should contain all breast tissue. The underwires should surround the breasts. The straps should feel secure. The bra should remain comfortable while moving.
Visit our Six-Point Bra Fit Check.
Test More Than One Bra Style
Do not test your size in only one bra. A single style may not suit your breast shape.
Try different cup constructions. Compare full-cup, balconette and plunge designs. Also compare different brands when possible.
Compare Moulded and Seamed Cups
Moulded cups provide a smooth shape beneath clothing. However, they hold one fixed shape. Seamed cups adapt more easily to varied breast shapes. They can also provide greater cup depth. Try both before deciding your calculated size is wrong. Sometimes the size is correct. Only the cup shape needs changing.
Move Around
Stand, sit and bend. Raise your arms above your head. Twist gently from side to side.
The band should remain in position. Your breasts should remain inside the cups. Nothing should pinch, rub or feel restrictive. Sports bras need a more active movement test. Jog, jump and reach before removing the tags. Follow the retailer’s returns conditions while testing.
Record What Fits
Keep a simple bra fit record.
Write down:
This information makes future purchases much easier. It also helps when comparing international brands.
Ask for Personalised Advice
Measurements can sometimes produce confusing results. Perhaps the band fits while the cups gape. Maybe one breast fits differently from the other. You may also sit between two sizes. Sports Bras Direct can help interpret these problems. Provide your measurements, current size and usual brand. Also explain exactly where the bra feels wrong. The more detail you provide, the more useful the advice becomes.
A well-fitting bra should feel secure. However, it should not feel painful.
The band should sit level around your body. It should provide most of the bra’s support.
The cups should contain your entire breast area. There should be no major overflow or empty space.
The centre front should sit appropriately. Most underwired bras should sit close to the sternum. The wires should not rest on breast tissue.
The straps should remain secure without digging.
Finally, the bra should stay comfortable during normal movement.
Measuring at home gives you valuable information. It can reveal why your usual bras feel wrong. It also creates a sensible starting size.
However, numbers cannot capture every part of bra fit. Breast shape matters. Bra construction matters. Brand sizing matters. Your personal comfort matters too.
Use your measurements to narrow the choices. Then let the real bra confirm the answer. Try several styles.
Complete the Six-Point Fit Check. Keep notes about brands that work well. With practice, finding your best fit becomes much easier.
Can I measure my bra size while wearing a bra?
Yes, when the bra is non-padded and fits reasonably well. Avoid padded, push-up or compressive bras.
Should I measure in centimetres or inches?
Use centimetres for Australian sizing. International calculators may also accept inches.
How tight should the underbust measurement be?
It should feel firm and secure. You should still breathe normally.
Why is my leaning measurement much larger?
Your breasts may have more projection or softer tissue. The difference can help guide cup-shape choices.
Which bust measurement should I use?
Start with the over-bust measurement. Use leaning and lying measurements as extra context.
Can a calculator guarantee my correct bra size?
No.It provides a starting size for trying bras.
Why do different calculators give different sizes?
Calculators may use different sizing formulas and charts. Brands also grade their bras differently.
Is a DD cup always large?
No. Cup volume depends on the accompanying band size. A 10DD is smaller than a 16DD.
Should a new bra fit on the tightest hook?
Usually, no. Most adjustable bras should begin on the loosest comfortable hook. This leaves room for tightening as the band stretches.
How often should I measure myself?
Measure whenever your usual bras fit differently. Also remeasure after meaningful body or hormonal changes.
What should I do when I sit between band sizes?
Try both options. You can also compare their sister sizes.
What happens when the size seems right but the bra still gaps?
The cup shape may not suit your breasts. Try a seamed, stretch or lower-coverage style.
Should I measure both breasts separately?
The main circumference measurement includes both breasts. Fit the final cup size to the larger breast. Use strap adjustments or inserts for the smaller side.
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