Bra Size Calculator - Find Your Perfect Fit
Use this bra size calculator to determine your correct band and cup size. Enter your underbust and bust measurements for instant results in US, UK, or EU systems.
Bra Size Calculator
Results
Sister sizes have the same cup volume but different band widths.
What is a Bra Size Calculator?
A bra size calculator is an essential tool designed to help you find your perfect fit by converting your body measurements into a standard band and cup size. Finding the right bra size is crucial for comfort, posture, and confidence.
- • Finding your starting size before shopping for new lingerie
- • Checking if your body shape has changed after weight loss or pregnancy
- • Converting between different international sizing systems
- • Identifying 'sister sizes' for specific bra styles
To find your overall fit, explore our Circle Skirt Calculator to estimate your full wardrobe dimensions.
How This Calculator Works
The calculation works by determining the mathematical relationship between your underbust and overbust measurements. Your band size is derived from your underbust measurement (rounded to the nearest even number), while your cup size is calculated by subtracting your band size from your fullest bust measurement.
According to ThirdLove Fit Guide, a perfectly fitting bra depends on the relationship between your band and bust measurements, where the band provides 80% of the support.
To ensure a complete fit, explore our Body Type Calculator to find your accessory sizes too.
Key Concepts Explained
Band Size
The numeric part of your bra size representing the circumference of your ribcage.
Cup Size
The lettered part representing the volume of breast tissue relative to your band.
Sister Sizing
Alternative sizes that share the same cup volume but have different band lengths.
Gore
The center piece between the cups that should lie flat against your breastbone.
To explore body proportions more deeply, use our Waist-to-Hip Ratio Calculator to understand your body composition.
How to Use This Calculator
Measure Underbust
Measure snugly against your ribcage while wearing a non-padded bra.
Measure Bust
Measure around the fullest part of your bust, level across your back.
Enter Data
Enter both measurements and select your preferred sizing system.
Review Size
Review your calculated size and suggested sister sizes for alternatives.
Once you have your measurements, check out our Body Fat Percentage Calculator to understand your overall body composition.
Benefits of Using This Calculator
- • Shopping Confidence: Eliminate guesswork when shopping for lingerie online.
- • Physical Comfort: Reduce physical discomfort caused by ill-fitting bands or straps.
- • Better Silhouette: Improve your silhouette and how clothes drape over your body.
- • Save Time: narrowing down your options to the most likely sizes.
To maximize health benefits, also use our BMI Calculator to track your weight-to-height benchmarks.
Factors That Affect Your Results
Breast Shape
Fullness at the top or bottom can affect how a cup fits, even if the volume is correct.
Brand Inconsistency
Manufacturers often use slightly different patterns, making charts brand-specific.
As published by Wikipedia Bra Size Standards, regional differences in cup labeling mean that a US 'DDD' is typically equivalent to a UK 'E' cup.
To control other clothing factors, explore our Calorie Calculator to find your footwear dimensions.
Frequently Asked Questions (FAQ)
Q: How do I know my correct bra size?
A: Your bra fits correctly when the band is level and snug (not digging in), the center gore lies flat against your chest, and there is no spillage or gaping in the cups. If you experience these issues, it is time to remeasure using our bra size calculator.
Q: How often should I measure my bra size?
A: Experts recommend measuring your bra size every six to twelve months. Significant life events such as weight fluctuations, starting a new exercise routine, or pregnancy can all lead to changes in your bust and band measurements.
Q: Is a 34C the same as a 36B?
A: Yes, 34C and 36B are 'sister sizes,' meaning they share the same cup volume. When you go up in band size, you must go down in cup size to maintain the same volume. This is useful if a 34C cup fits but the band is too tight.
Q: How should a bra fit correctly?
A: A well-fitting bra should feel supportive but comfortable. The band should provide the majority of the support, while the straps should remain in place without digging into your shoulders. The cups should fully contain your breast tissue without any wrinkles or gaps.
Q: What are sister sizes in bras?
A: Sister sizes are groups of bra sizes that have the same cup volume but different band measurements. For example, if you find your calculated size is a 32D but the band is too tight, a 34C will offer the same cup space with a more comfortable band.
Q: How do I measure myself for a bra at home?
A: To measure at home, you need a soft tape measure. Wrap it snugly under your bust for the band measurement, then loosely around the fullest part of your chest for the bust measurement. Ensure the tape is parallel to the floor for both steps.