Find your perfect bra size with our accurate measurement calculator
Enter Your Measurements
All measurements should be in inches. Measure snugly but not tightly.
Underbust Measurements
Bust Measurements
Your Recommended Size
Enter your measurements to see your recommended size
Size Visualization
How to Measure Correctly
Underbust Measurements
Measure around your ribcage directly under your bust. Take three measurements: loose, snug, and tight.
Bust Measurements
Measure around the fullest part of your bust. Take measurements while standing, leaning forward, and lying down.
Calculate
Our calculator uses the ABraThatFits algorithm to determine your perfect size based on all six measurements.
Cup Size Reference Chart
Finding the Perfect Fit
Band Fit
The band should be snug and parallel to the ground. It should provide most of the support.
Cup Fit
Your breasts should fully fill the cups without spillage or gaping. The wire should encase all breast tissue.
Comfort
A well-fitting bra should be comfortable to wear all day without digging, pinching, or riding up.
Mastering Bra Sizing with the ABraThatFits Calculator
The ABraThatFits calculator has revolutionized how women approach bra fitting, moving away from outdated sizing methods to a scientifically-backed system that considers individual breast shape, distribution, and body proportions. This comprehensive guide will help you understand and utilize this powerful tool to find your perfect fit.
Research suggests that 70-85% of women wear incorrectly sized bras, leading to discomfort, poor posture, and even health issues. The ABraThatFits method addresses these problems through a nuanced approach that recognizes the diversity of women’s bodies and breast characteristics.
The Problem with Traditional Bra Fitting Methods
Traditional bra fitting methods, particularly the “+4 method” still used by many retailers, often result in poorly fitting bras that compromise comfort and support.
The +4 Method: An Outdated Approach
The +4 method involves adding 4 inches (or 5 inches for odd-numbered band sizes) to the underbust measurement to determine band size. This approach dates back to a time when bras had less elastic content and doesn’t account for modern materials and construction.
Common Issues with Incorrect Sizing
Wearing an incorrectly sized bra can cause numerous problems:
- Band riding up in the back, reducing support
- Shoulder straps digging in or slipping off
- Breast tissue spilling out of cups (quadboob)
- Gaps in cups causing improper shape
- Underwire sitting on breast tissue rather than ribcage
- Back, shoulder, and neck pain
Percentage of Women Wearing Incorrect Bra Sizes by Age Group
The ABraThatFits Methodology: A Scientific Approach
The ABraThatFits calculator uses six precise measurements to determine bra size, accounting for breast shape, distribution, and individual body characteristics.
The Six Essential Measurements
Unlike traditional methods that use only two measurements, ABraThatFits requires six precise measurements:
1. Underbust Measurements
- Snug Underbust: Tape comfortably snug around ribcage
- Tight Underbust: Tape as tight as possible, exhaling fully
2. Bust Measurements
- Standing Bust: Tape loosely around fullest part of breasts
- Leaning Bust: Measure while bending forward 90 degrees
- Lying Bust: Measure while lying flat on your back
Why Six Measurements Matter
Multiple measurements account for breast characteristics that affect fit:
- Projection: Difference between standing and leaning measurements indicates projection
- Firmness: Difference between measurements helps determine breast firmness
- Distribution: Measurements reveal where breast tissue is distributed
Band Size = Snug Underbust Measurement (Rounded to nearest even number)
Cup Size = Difference between Bust and Underbust Measurements
Comparison of Measurement Methods: Traditional vs. ABraThatFits
Understanding Cup Sizes and Volume
Cup size is relative to band size, meaning a D cup on a 32 band has different volume than a D cup on a 38 band. This concept, called “sister sizing,” is crucial to understanding bra fit.
Sister Sizing Explained
Sister sizes are bras with different band sizes but the same cup volume. When you go up a band size, you need to go down a cup size to maintain the same volume, and vice versa.
| Band Size | Cup Size | Sister Size Up | Sister Size Down | Approx. Cup Volume (ml) |
|---|---|---|---|---|
| 32 | D | 34C | 30DD | 710 |
| 34 | D | 36C | 32DD | 810 |
| 36 | D | 38C | 34DD | 920 |
| 38 | D | 40C | 36DD | 1040 |
| 40 | D | 42C | 38DD | 1180 |
Cup Size Progression
Cup sizes follow an alphabetical progression that continues beyond D with double and eventually triple letters in many sizing systems:
Standard Progression: A, B, C, D, DD, E, F, FF, G, GG, H, HH, J, JJ, K…
US vs. UK Sizing: DD=E, DDD=F, DDDD=G in US sizing
Cup Volume Comparison Across Band Sizes
Understanding Breast Shape Characteristics
Breast shape is as important as size when finding the right bra. The ABraThatFits method considers several shape characteristics that affect fit.
Projection: Shallow vs. Projected
Projection refers to how far breasts extend from the chest wall when supported:
- Shallow Breasts: Tissue spread over a larger area of chest wall
- Projected Breasts: Tissue extends more directly forward from chest wall
- Even Projection: Balanced between shallow and projected
Fullness Distribution
Fullness describes where breast tissue is concentrated when supported:
- Full on Top (FOT): More tissue above nipple
- Full on Bottom (FOB): More tissue below nipple
- Even Fullness: Balanced distribution above and below nipple
Root Width and Height
Root characteristics determine where breast tissue attaches to the chest wall:
Narrow Root: Tissue concentrated in a smaller area
Wide Root: Tissue spread across a larger area of chest
Short Root: Vertical tissue distribution is shorter
Tall Root: Vertical tissue distribution is longer
Breast Shape Distribution in Population
The ABraThatFits Calculator Algorithm
The calculator uses a sophisticated algorithm that goes beyond simple arithmetic to provide accurate size recommendations.
Band Size Calculation
Band size is primarily determined by the snug underbust measurement, with adjustments based on the tight measurement:
If (Tight Underbust – Snug Underbust) ≤ 2 inches → Band Size = Snug Underbust
If (Tight Underbust – Snug Underbust) > 2 inches → Consider sizing up for comfort
Cup Size Calculation
Cup size uses an average of the three bust measurements, weighted differently based on breast characteristics:
For even fullness: Average = (Standing + Leaning + Lying) ÷ 3
For FOT: Average weighted toward leaning measurement
For FOB: Average weighted toward lying measurement
Size Adjustments for Specific Scenarios
The algorithm makes adjustments for:
- Pregnancy and breastfeeding
- Post-surgical considerations
- Hormonal fluctuations
- Weight changes
- Age-related tissue changes
Algorithm Accuracy Compared to Professional Fittings
Bra Styles for Different Breast Shapes
Once you know your size and shape, selecting the right bra style is essential for optimal fit and comfort.
Balconette Bras
Ideal for many shapes, particularly good for:
- Shallow to average projection
- Even to full-on-bottom shapes
- Creating rounded, lifted appearance
Full Cup Bras
Provide maximum coverage and support for:
- Larger cup sizes (D+)
- Full-on-top shapes
- Those needing maximum support
Plunge Bras
Low center gore works well for:
- Close-set breasts
- Even to center-full shapes
- Wearing with low-cut clothing
For Projected Breasts
- Seamed cup styles
- Narrow wires
- Projected cup designs
- Balconette or full cup
For Shallow Breasts
- Molded or seamless cups
- Wide, shallow wires
- Demisphere styles
- Half-cup or balconette
For Full-on-Top
- Open-on-top styles
- Stretch lace at top
- Vertical seam emphasis
- Balconette or half-cup
For Full-on-Bottom
- Closed-on-top styles
- Horizontal seam emphasis
- Full cup or balconette
- Side support panels
Bra Style Effectiveness by Breast Shape
Special Considerations and Adjustments
Certain life stages and conditions require special fitting considerations that the ABraThatFits calculator accommodates.
Pregnancy and Nursing
Breast changes during pregnancy and lactation require specific fitting approaches:
- Increased ribcage expansion in later pregnancy
- Fluctuating breast size and sensitivity
- Nursing accessibility requirements
- Stretch fabrics for accommodation changes
Post-Surgical Fitting
After breast surgery, fitting considerations include:
- Asymmetry correction
- Scar tissue accommodation
- Specialized pocketed bras for prosthetics
- Front-closure options for limited mobility
Weight Fluctuations
Significant weight changes affect bra fitting in predictable ways:
Weight Gain: Typically increases both band and cup size
Weight Loss: Band size decreases more than cup size initially
Maintenance Phase: Fluctuations stabilize after 3-6 months
Common Fit Issues and Their Solutions
Even with accurate measurements, you may encounter fit issues that require specific adjustments.
Band Issues
Band problems are among the most common fitting issues:
| Problem | Likely Cause | Solution |
|---|---|---|
| Band rides up | Band too large | Decrease band size |
| Band feels tight | Cups too small | Increase cup size |
| Band digs in | Band too small or style mismatch | Try different style or extender |
Cup Issues
Cup fit problems indicate size or shape mismatches:
Quadboob (spillage): Cups too small or too shallow
Gapping: Cups too large, too tall, or shape mismatch
Wrinkling: Cups too projected or too large
Conclusion
The ABraThatFits calculator represents a significant advancement in bra fitting methodology, moving beyond outdated systems to a personalized, scientific approach. By considering individual breast characteristics and using multiple precise measurements, this method helps women find bras that offer superior comfort, support, and appearance.
Remember that the calculator provides a starting point rather than a definitive answer. Bra fitting involves trial and adjustment, and what works perfectly for one person might need modification for another. Use the calculator as a guide, but trust your comfort and how the bra makes you feel as the ultimate measure of success.
Frequently Asked Questions About Bra Fitting
Store fitters often use outdated methods like the +4 system or limit their size range based on what the store carries. The ABraThatFits calculator uses a more accurate, individualized approach that considers your specific measurements and breast characteristics. Additionally, store fitters may be incentivized to fit you into sizes they have in stock rather than your ideal size.
It’s recommended to remeasure every 6-12 months, or whenever you experience significant body changes such as weight fluctuation of 10+ pounds, pregnancy, breastfeeding, surgery, or hormonal changes. Even without noticeable changes, subtle shifts in breast tissue distribution can affect fit over time.
Many women are surprised by their ABraThatFits size because we’re accustomed to thinking of D+ cups as very large. In reality, cup size is relative to band size—a 30DD has similar volume to a 34C. If the size seems surprising, trust the measurements and try it. The calculator is based on extensive data from thousands of successful fittings.
The three bust measurements (standing, leaning, lying) provide information about breast characteristics that affect fit. The difference between these measurements helps determine projection, firmness, and how breast tissue is distributed. Using an average of these measurements provides a more accurate representation of your breast volume than a single measurement.
A well-fitting bra should: 1) Have a band that sits parallel to the floor and doesn’t ride up, 2) Contain all breast tissue without spillage or gaping, 3) Have underwires that follow your breast root without sitting on tissue, 4) Have straps that stay in place without digging in, and 5) Feel comfortable throughout the day without needing adjustment.
It’s common to have slight asymmetry, but for significant differences, fit the larger breast and use padding or cookies on the smaller side. Some brands offer bras with removable pads. For extreme asymmetry, specialty brands or custom options may be necessary. The calculator can provide a starting point based on your larger breast measurements.
Bra sizing isn’t standardized across brands, much like clothing sizes. Different manufacturers use different scaling, materials, and design philosophies. A 34DD in one brand might fit like a 32E in another. This is why it’s important to try on bras rather than relying solely on the size tag. The calculator gives you a starting point to begin your search.
A new bra might feel slightly different but shouldn’t be painful. Mild tightness that eases within 15-20 minutes is normal breaking-in. Painful underwires, red marks that last more than 30 minutes after removal, or any numbness indicates poor fit. A properly fitting bra should be comfortable from the first wear, with maybe minor adjustments as it molds to your shape.