How to Measure Your Strapless Bra Size Correctly

Getting an accurate measurement is the foundation of finding a strapless bra that actually stays in place. Unlike regular bras where straps can compensate for minor fit issues, strapless bras rely entirely on the band and cups to provide support. Here's how professional bra fitters measure for the perfect fit.

Step 1: Measure Your Band Size

Your band size is the foundation of strapless bra support. Without straps to distribute weight to your shoulders, the band does approximately 80% of the work in a strapless bra—even more than in a regular bra.

The Correct Measurement Technique

Stand in front of a mirror and wrap your measuring tape around your ribcage, directly under your bust where your bra band normally sits. The tape should be:

• Level all the way around — not dipping down at the back
• Snug but not tight — you should be able to fit one finger underneath
• Against your skin — not over clothing

Take a normal breath and note the measurement in centimetres. Australian band sizes work differently from US sizes, so here's how to convert your measurement:

Step 2: Measure Your Bust

Next, measure around the fullest part of your bust. This is typically across the nipple line, but if your breasts sit lower, measure wherever they are fullest. Keep the tape level and don't pull it tight—it should just rest against your skin.

For the most accurate measurement, lean forward at a 90-degree angle and let your breasts hang naturally. This technique, known as the "leaning method," captures your full breast volume and is especially helpful for those with soft or pendulous breast tissue.

Why the Leaning Method Matters for Strapless Bras

Standard standing measurements often underestimate cup size because breast tissue can spread across your chest when you're upright. In a regular bra, straps help gather this tissue into the cups. Without straps, your strapless bra cups need to accommodate your full breast volume on their own—making an accurate bust measurement critical.

Step 3: Calculate Your Cup Size

Your cup size is determined by the difference between your bust measurement and your band measurement:

• 10 cm difference = A cup
• 12.5 cm difference = B cup
• 15 cm difference = C cup
• 17.5 cm difference = D cup
• 20 cm difference = DD/E cup
• 22.5 cm difference = E/F cup
• 25 cm difference = F/G cup

For example, if your underbust measures 75 cm (band size 12) and your bust measures 92.5 cm, the difference is 17.5 cm, giving you a cup size of D. Your starting size would be 12D.

Common Measurement Mistakes to Avoid

After fitting thousands of women, we've seen these errors repeatedly:

Measuring Over a Padded Bra

Padded bras add centimetres to your bust measurement, resulting in a cup size that's too large. Always measure over a thin, unpadded bra or no bra at all.

Pulling the Tape Too Tight

An overly snug measurement leads to a band size that's too small. While you want a firm band for strapless support, an excessively tight band causes spillage, discomfort, and that dreaded "back bulge."

Measuring at the Wrong Time

Breast size fluctuates throughout your menstrual cycle, with many women experiencing up to a cup size difference. For the most representative measurement, avoid measuring during the week before your period when breasts are often at their largest.

Using Old Measurements

Your bra size can change due to weight fluctuations, pregnancy, breastfeeding, hormonal changes, and ageing. Re-measure yourself at least once a year, or whenever your current bras feel uncomfortable.

Strapless Bra Fit Adjustment Tips

Even with perfect measurements, you may need to adjust for strapless styles:

• Consider sizing down in the band: Many women find that going down one band size (and up one cup size) provides better grip in strapless styles. The snugger band compensates for the lack of straps.
• Don't ignore cup shape: Some strapless bras have shallow cups while others offer more projection. If your calculated size gapes or feels tight, the cup shape may not suit your breast shape.
• Test with movement: Always do the "raise your arms" test when trying on a strapless bra. If it slips down when you lift your arms overhead, you need a tighter band or more supportive style.

When to Seek Professional Fitting

While self-measurement works well for most women, consider visiting a professional bra fitter if:

• Your measurements fall between sizes
• You have asymmetrical breasts (most women do!)
• You've recently experienced significant body changes
• You're shopping for a special occasion and need absolute certainty
• You're a larger cup size (DD and above) where fit is more critical

Many Australian department stores and lingerie boutiques offer free fitting services. Even if you end up purchasing online, a professional fitting can confirm your size and help you understand what features to look for.

Armed with accurate measurements, you're ready to start shopping for your perfect strapless bra. Remember that measurements are a starting point—you may need to try a few sizes and styles to find your ideal fit. Check out our Beginner's Guide to Strapless Bras for advice on choosing between different styles, or use our comparison tool to evaluate specific products.