How to Know Your Bust Size: Expert Guide to Accurate Bra Fitting

Knowing your true bust size is the foundation of a supportive, flattering, and comfortable bra fit. Yet, many women wear the wrong size without realizing it—leading to discomfort, poor posture, and compromised confidence. Whether you're shopping for a new everyday bra, a special occasion piece, or supportive swimwear, an accurate bust measurement is key.

In this expert guide, we walk you through how to measure your bust size correctly, understand what the numbers and letters mean, and recognize signs of a well-fitted bra.

Why Bust Size Matters

A properly fitted bra does more than lift and shape—it enhances your silhouette, improves posture, and prevents back and shoulder pain. Bras that are too tight or too loose can cause bulging, gaping cups, slipping straps, and even skin irritation. Knowing your correct size helps ensure:

• Proper support for your breast tissue

• Longer-lasting bras due to reduced wear and tear

• Confidence in clothing, from tees to tailored pieces

Step-by-Step: How to Measure Your Bust Size at Home

All you need is a soft measuring tape, a mirror, and ideally, a non-padded bra for accurate results.

1. Measure Your Band Size (Underbust)

• Wrap the tape snugly around your ribcage, directly under your bust.

• Make sure the tape is level across your back.

• Round to the nearest whole number.

  • If the number is even, add 4.

  • If the number is odd, add 5.

• The result is your band size.

Example: If your underbust measurement is 31", your band size is 36 (31 + 5).

2. Measure Your Bust (Overbust)

• Place the measuring tape around the fullest part of your bust.

• Keep it level and slightly looser than the band measurement.

• Round to the nearest whole number.

Example: If your bust measures 40", write it down.

3. Calculate Your Cup Size

Subtract your band size from your bust measurement. The difference corresponds to a cup size:

Example: Bust = 40", Band = 36" → 40 - 36 = 4 → Cup Size D
Your bra size = 36D

Common Signs You're Wearing the Wrong Bra Size

• Straps digging in or falling off your shoulders

• Band riding up your back

• Cups gaping or overflowing

• Underwire poking or not sitting flat

• Discomfort after a few hours of wear

If you’re nodding yes to any of the above, it’s time for a reassessment.

Professional Fittings: Why They're Worth It

While home measuring is helpful, professional fittings—like those offered at Olivia Paisley Intimates—provide personalized attention, access to a wider size range, and recommendations based on real-life body shape and support needs. Fitters are trained to consider not just numbers, but breast shape, tissue distribution, and bra construction.

Bust Size vs. Bra Size: Know the Difference

• Bust Size: Your overbust measurement (in inches)

• Bra Size: A combination of band size and cup size (e.g., 36D)

Both are essential to finding bras that fit and feel great.

Final Tips for Getting the Best Fit

• Re-measure every 6–12 months, especially after weight changes, pregnancy, or hormonal shifts.

• Different brands fit differently—always try on or read sizing guides.

• Comfort comes first—a well-fitting bra should support without digging, pinching, or riding up.

Conclusion

Knowing your bust size isn’t just about numbers—it’s about empowerment. A properly fitted bra enhances your daily life with better support, comfort, and confidence. Use these measuring tips at home, or visit a local expert fitter like Olivia Paisley Intimates to ensure every bra in your drawer works with you, not against you.