Find your perfectly fitting bra size using the comprehensive “A Bra That Fits” (ABTF) method. Input your six essential measurements below for an accurate suggestion.
A Bra That Fits Calculator
Detailed Calculation Steps
A Bra That Fits Calculator Formula
Avg. Bust (in) = (Standing Bust + Leaning Bust + Lying Bust) / 3
Cup Volume (in) = Avg. Bust – Band Size
Cup Size = Volume Difference (1=A, 2=B, 3=C, etc. based on US/UK progression)
Formula Source: A Bra That Fits Official, Busty Resources
Variables Explained
The calculation requires five measurement inputs, taken in inches or centimeters, and one gender-specific input.
- Snug Underbust: How tight the tape should be for comfortable wear. Used to determine the band size.
- Tight Underbust: The tightest measurement when exhaling fully. Used as a baseline for the smallest possible band size.
- Standing Bust: Measurement taken standing up, around the fullest part of the bust.
- Leaning Bust: Measurement taken leaning over at a 90-degree angle. Helps capture tissue mobility.
- Lying Bust: Measurement taken lying down flat on your back. Helps account for various tissue shapes.
- Assigned Gender: Affects the final cup size progression used in the calculation, as some methods are optimized for specific body types.
What is the A Bra That Fits Calculator?
The “A Bra That Fits” (ABTF) method is a specialized bra sizing technique designed to provide a more accurate and nuanced size recommendation than traditional methods. Unlike the outdated “+4” method, the ABTF calculator uses five distinct bust measurements—standing, leaning, and lying—combined with two underbust measurements (snug and tight).
This approach is highly regarded in online communities for accommodating various breast shapes, volumes, and tissue types, resulting in a more precise fit. The final size is generated not just on average differences but also on factors like body composition and assigned gender, which can influence how breast tissue distributes.
The goal is to eliminate common fitting issues like a riding up band, digging straps, or “quad-boob” spillage, leading to improved posture and comfort. Always treat the result as a starting point for trying on bras, as individual brand shapes will vary.
How to Calculate Your Bra Size (Example)
Let’s use an example of measurements taken in inches: Snug Underbust (32), Tight Underbust (31), Standing Bust (38), Leaning Bust (39), Lying Bust (37).
- Determine the Band Size: The snug underbust is 32 inches. Rounding to the nearest even number gives us a Band Size of **32**.
- Calculate Average Bust: $$(38 + 39 + 37) / 3 = 114 / 3 = 38 \text{ inches}$$
- Calculate Cup Volume: Average Bust minus Band Size gives the cup volume difference: $$38 – 32 = 6 \text{ inches}$$
- Determine Cup Size: A 6-inch difference corresponds to a **F** cup (US/UK progression: 1=A, 2=B, 3=C, 4=D, 5=DD/E, 6=DDD/F).
- Final Suggested Size: The result is **32F**.
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- US/UK Shoe Size Converter
Frequently Asked Questions (FAQ)
Using standing, leaning, and lying measurements ensures the calculator accounts for different types of breast tissue and how they respond to gravity. This averages out variations in tissue density and shape, providing a more accurate baseline for cup volume.
US and UK sizing are identical up to a D cup. After that, US sizing uses double letters (DD, DDD, G, H), while UK sizing uses single letters (DD, E, F, FF, G). This calculator uses the UK progression (DD, E, F, FF…) as it is more consistent, and will display both standard equivalents.
Yes. Many people wear a band size that is too large and a cup size that is too small, often due to the outdated “+4” fitting rule. The ABTF method often results in a smaller band and a larger cup size than conventionally measured, which generally leads to a much better fit.
No. The calculator automatically detects your selected unit (inches or centimeters) and converts all input values to inches for the core calculation, ensuring the final size recommendation is consistent regardless of the input unit.