Aerie Bra Size Calculator
Find your perfect Aerie fit in two simple steps. Measure your rib cage and bust, enter the values below, and we’ll calculate your recommended Aerie bra size.
Wrap a measuring tape snugly around your rib cage, just beneath your bust.
Please enter a valid number.
Measure around the fullest part of your bust. The tape should be level and not too tight.
Please enter a valid number.
What is an Aerie Bra Size Calculator?
An Aerie bra size calculator is a tool designed to help you find your most accurate bra size based on the specific sizing system used by Aerie. While many bra brands use a traditional “+4” method, Aerie’s sizing is unique and often aligns more closely with modern fitting techniques. This calculator interprets your personal measurements—your rib cage (underbust) and fullest bust measurement—to recommend a starting size specifically for Aerie bras. The goal is to move beyond the confusing and often inaccurate old rules to find a bra that offers superior support and comfort.
Aerie Bra Size Formula and Explanation
Unlike outdated methods, the modern formula used by this calculator focuses on two key measurements to determine your size. The logic is straightforward:
- Determine the Band Size: The Aerie method uses a size chart to convert your underbust (rib cage) measurement to a band size. For example, a rib cage measurement of 29-30 inches typically corresponds to a 34 band size in Aerie’s system. This calculator automates that lookup process for you.
- Determine the Cup Size: The cup size is found by calculating the difference between your fullest bust measurement and your *calculated band size*. Each inch of difference corresponds to a cup letter.
The final formula can be expressed as: Cup Size = Bust Measurement – Band Size
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| Rib Cage Measurement | The measurement in inches or cm directly under the bust. | in / cm | 26 – 44 in |
| Bust Measurement | The measurement in inches or cm around the fullest part of the bust. | in / cm | 28 – 50 in |
| Band Size | The numeric part of your bra size (e.g., 34). Derived from the Rib Cage measurement. | (Numeric Label) | 30 – 42 |
| Cup Difference | The difference (in inches) between the Bust Measurement and the Band Size. | inches | 0 – 8 in |
Practical Examples
Let’s see how the calculation works with some real-world numbers:
Example 1:
- Inputs: Rib Cage = 29 inches, Bust = 35 inches
- Band Calculation: A 29-inch rib cage measurement translates to a 34 band size based on Aerie’s chart.
- Cup Calculation: 35 inches (Bust) – 34 (Band Size) = 1 inch difference.
- Result: A 1-inch difference is a B cup. Your starting size is 34B.
Example 2:
- Inputs: Rib Cage = 33 inches, Bust = 39 inches
- Band Calculation: A 33-inch rib cage measurement translates to a 38 band size.
- Cup Calculation: 39 inches (Bust) – 38 (Band Size) = 1 inch difference.
- Result: A 1-inch difference is a B cup. Your starting size is 38B.
How to Use This Aerie Bra Size Calculator
- Select Your Unit: Choose between inches and centimeters from the dropdown menu. The calculator will automatically handle the conversion.
- Measure Your Rib Cage: Using a soft measuring tape, measure around your torso directly under your bust. Make sure the tape is level and snug, but not digging in. Enter this number into the “Rib Cage (Underbust)” field.
- Measure Your Bust: Measure around the fullest part of your bust. It’s best to do this while wearing a non-padded bra to ensure the most accurate measurement. Enter this number into the “Fullest Part of Bust” field.
- Interpret the Results: The calculator will instantly display your recommended Aerie bra size. It will also show your calculated band and cup letter.
- Consider Sister Sizes: Check the “Your Sister Sizes” table. If your recommended size doesn’t feel perfect, a sister size might be a better fit. For instance, if a 34C feels too loose in the band, try its sister size down: 32D.
Key Factors That Affect Bra Fit
- Band Snugness: The band provides about 80% of a bra’s support. It should be snug and sit parallel to the floor without riding up. You should be able to fit two fingers comfortably underneath it.
- Cup Fit: Your breast tissue should be fully contained within the cups with no spilling over the top (quad-boob) or gaping. The center gore (the part between the cups) should lie flat against your sternum.
- Strap Adjustment: Straps should be adjusted to provide a small amount of lift without digging into your shoulders. They should not be doing all the support work; that’s the band’s job.
- Bra Style: Different styles (like plunge, t-shirt, or full coverage) are designed for different breast shapes. A size that fits perfectly in one style might not work in another.
- Breast Shape: Whether your breasts are round, teardrop, wide-set, or shallow can influence which bra styles will fit you best, even if the size is technically correct.
- Material and Stretch: Bras with more elastane or stretch in the band may feel looser over time. You might start on the loosest hook and move inward as the bra stretches with wear.
Frequently Asked Questions (FAQ)
- 1. Why is my Aerie size different from other brands?
- Aerie often avoids the outdated “+4 inch” method, which can result in a smaller, more supportive band size and a larger cup size than what you might find from other brands. This calculator is calibrated for Aerie’s specific fit model.
- 2. What is a sister size?
- A sister size is an equivalent cup volume on a different band size. For example, a 34B, 32C, and 36A all have the same cup volume. Knowing your sister sizes gives you more options if a band or cup doesn’t fit perfectly.
- 3. The calculator gave me a size I’ve never worn. Is it correct?
- It’s very common for people to be wearing the wrong bra size. We recommend trying the suggested size, as it’s based on a modern fitting method that prioritizes support from the band. Give it a try, especially if you experience issues like a riding-up band or digging straps.
- 4. How often should I measure myself?
- It’s a good idea to remeasure every 6-12 months, or after significant body changes like weight fluctuation, pregnancy, or starting a new fitness routine. Your body changes, and your bra size can too.
- 5. What if I’m between sizes?
- If you’re between band sizes, consider how you prefer your band to fit. If you like a very snug fit, try the smaller band size with its corresponding sister-size cup. If you prefer comfort, try the larger band. Trying a sister size is often the perfect solution.
- 6. My cups are gaping. What does that mean?
- Gapping can mean the cups are too big. However, it can also happen if the band is too loose and not pulling the cups taut against your body. First, try tightening the band or trying a sister size with a smaller band and larger cup (e.g., moving from 36B to 34C).
- 7. Why shouldn’t I just add 4 inches to my rib cage measurement?
- The “+4 method” is a relic from a time when bras were made of non-stretch materials. With modern elastic fabrics, adding 4 inches almost always results in a band that is too loose to provide proper support, forcing the shoulder straps to do all the work.
- 8. How do I know if my band is too tight?
- A new bra should fit snugly on the loosest hook. If it’s digging in, leaving painful red marks, or feels restrictive when you breathe, it’s too tight. Try a sister size up (e.g., from 32C to 34B).
Related Tools and Internal Resources
Explore more of our resources to perfect your style and fit:
- Bra Fit Guide: A deep dive into diagnosing common fit issues.
- Understanding Bra Styles: Learn the difference between a plunge, balconette, and t-shirt bra.
- {related_keywords}: Explore our collection of comfortable and stylish bralettes.
- {related_keywords}: Perfect for workouts and an active lifestyle.
- {related_keywords}: Our guide to finding the perfect underwear to match your new bra.
- Care and Maintenance: Tips on how to wash and care for your bras to make them last longer.