Common Mistakes When Measuring for Bra Size and How to Fix Them

Why Accurate Bra Sizing Matters

Common Bra Sizing Mistakes and Solutions

1. Avoid the Mistake of +4/+5 Sizing Method

• Mistake: Adding 4–5 inches to the underbust measurement to determine band size, a US retail practice from decades ago, is still common in stores like Victoria’s Secret. For example, a 30” underbust becomes a 34” band, resulting in a loose band and smaller cups (e.g., 34B instead of 30D). 
• Impact: Loose bands ride up, reducing support, while small cups cause spillage or quad-boob, especially for projected breasts.
• Solution:
  • Use the snug underbust measurement, rounded to the nearest even number, as your band size (e.g., 31.5” → 32 band).
  • Measure underbust three ways (loose, snug, tight) to account for ribcage and tissue compressibility. 
  • Example: Snug underbust 30”, bust 35” → 35 - 30 = 5” → DD cup → 30DD.
  • Tip: Avoid +4 fittings; if in-store, request a snug band and try sister sizes (e.g., 30DD → 32D).

2. Measuring Over Clothing or a Padded Bra

• Mistake: Taking measurements over a shirt, bra, or padded bra adds extra inches, inflating band and bust sizes. Padded, molded bras compress tissue, skewing bust measurements.
• Impact: Inaccurate measurements lead to loose bands or oversized cups, causing gapping or insufficient coverage, especially for shallow breasts.
• Solution:
  • Measure bare-skinned or in a thin, non-padded bra to capture true dimensions.
  • Use a soft tape measure, keeping it level (check in a mirror) and parallel to the floor for underbust and bust.
  • Tip: Take measurements post-menstrual cycle to avoid hormonal swelling, which can add 0.5–1 inch to bust. If you have fit issues during your cycle, consider adding a bra or two specifically for that time. 

3. Incorrect Tape Placement

• Mistake: Measuring the underbust too high (above the IMF) or bust at the wrong point (e.g., under or above nipples) distorts results. Misplacing the tape is common for pendulous or sagging breasts.
• Impact: High underbust measurements yield loose bands; incorrect bust placement underestimates cups, causing spillage for projected breasts or gapping for shallow ones.
• Solution: Correct Bra Measurement Placement
  • Underbust: Measure directly under breasts, where the bra band sits, ensuring the tape is snug and level.
  • Bust: Measure at the fullest part (usually nipple level) in three positions: standing, leaning forward 90 degrees, and lying down, as per ABTF’s six-measurement method. Leaning captures pendulous tissue, standing suits firm breasts.
  • Tip: Use a mirror or phone's camera screen to ensure tape alignment. For sagging breasts, lift tissue gently to find the IMF.

4. Ignoring Breast Shape and Fullness

• Mistake: Assuming a calculated size (e.g., 32F) fits all bra styles ignores breast shape (shallow, projected, full-on-top, full-on-bottom) and root width (wide, narrow). Shape confusion is frequent and ultra-common.
• Impact: Mismatched shapes cause fit issues: shallow bras spill for projected breasts; deep cups gap for shallow breasts.
• Solution:
  • Assess shape: lean forward to check fullness (top-heavy = FOT, bottom-heavy = FOB) and trace breast root for width.
  • Choose style based on shape:
    • Projected, Narrow Roots: Unlined plunges.
    • Shallow, Wide Roots: Molded t-shirt bras.
  • Tip: Try multiple styles in your size to match shape.

5. Not Re-Measuring Regularly

• Mistake: Using old measurements despite weight changes, pregnancy, menopause, or hormonal shifts leads to outdated sizes. Breasts can change 0.5–2 cup sizes during life stages.
• Impact: Outdated sizes cause discomfort, with loose bands or tight cups exacerbating back pain or tissue migration.
• Solution: When to Re-Measure Bra Size
  • Re-measure every 6–12 months or after significant changes (e.g., 10-pound weight shift, pregnancy, menopause).
  • Use ABTF’s calculator for consistency, inputting all six measurements to track changes.

6. Relying Solely on Calculator Results

• Mistake: Treating calculator outputs (e.g., 32F) as definitive without trying bras overlooks brand variations and fit nuances. 
• Impact: Rigid adherence leads to persistent fit issues, like tight bands or gapping cups.
• Solution:
  • Use the calculator as a starting point, trying the recommended size and sister sizes (e.g., 32F → 34E, 30FF) to account for brand differences.
  • Check brand fit notes.

Practical Steps to Avoid Mistakes

1. Use the Right Tools: Invest in a soft tape measure and use ABTF’s six-measurement calculator for precision.
2. Measure Bare-Skinned: Remove clothing or padded bras to ensure accuracy, checking tape alignment in a mirror.
3. Account for Shape: Use ABTF’s shape quiz or community feedback to match styles to your breast shape.
4. Try Sister Sizes: Order your calculated size and two sister sizes (e.g., 32DD, 34D, 30E) to find the best fit.
5. Re-Measure Regularly: Update measurements every 6–12 months or after life changes, logging results for consistency.
6. Seek Expert Advice: Reach out to us here, visit specialty stores or post on r/ABraThatFits for professional or community input, avoiding +4 fittings.

Final Thoughts