Sister sizes in bras refer to equivalent bra sizes that maintain the same cup volume despite having different band sizes and cup letters. This concept allows for adjustments in fit when the band feels too tight or loose while preserving the cup’s capacity, offering women more flexibility in finding their ideal bra fit.
Understanding Cup Volume Equivalence Using 36G as an Example
Understanding cup volume equivalence is crucial when exploring sister sizes. Let’s use 36G bras as an example to illustrate this concept:
- 36G has the same cup volume as 34GG, 38FF, 40F, and 42E.
- Moving up in band size (e.g., 38FF) requires going down in cup letter to maintain volume.
- Moving down in band size (e.g., 34GG) requires going up in cup letter to keep the same volume.
This equivalence occurs because cup size is relative to band size. A G cup on a 36 band contains the same volume as an FF cup on a 38 band or a GG cup on a 34 band. However, while the volume remains constant, the shape and distribution of the cup may vary slightly between sizes, potentially affecting fit and comfort.
It’s important to note that sister sizing works best when adjusting one size up or down from your true size to ensure optimal support and fit.
Adjusting Band and Cup Sizes
When adjusting band and cup sizes, it’s essential to understand how these changes affect the overall fit of the bra. If the band feels too tight but the cups fit well, go up one band size and down one cup size to maintain the same cup volume. For example, if a 34C feels snug in the band, try a 36B. Conversely, if the band is too loose but the cups fit properly, go down one band size and up one cup size, such as moving from a 34C to a 32D.
- For a tighter band: Go down one band size, up one cup letter (e.g., 34E to 32F).
- For a looser band: Go up one band size, down one cup letter (e.g., 32F to 34E).
- If cups are too small: Keep band size, go up one cup letter (e.g., 34E to 34F).
- If cups are too large: Keep band size, go down one cup letter (e.g., 34E to 34DD).
Remember that these adjustments work best when moving one size up or down from your true size. Making drastic changes in band size may affect the overall support and fit of the bra, potentially leading to discomfort or inadequate support.
Common Misconceptions About Sister Sizes
Sister sizes are often misunderstood, leading to common misconceptions that can hinder finding the perfect bra fit. One prevalent myth is that sister sizes are interchangeable for everyday wear. While they can be useful alternatives, relying on sister sizes too frequently may compromise support and comfort.
Another misconception is that sister sizing works equally well in all directions. In reality, sizing up in the band tends to be more forgiving than sizing down, as a too-tight band can cause discomfort and affect breast tissue.
- Sister sizes are not always suitable for long-term wear.
- Sizing up in the band is generally more comfortable than sizing down.
- Cup volume remains constant, but overall bra proportions change with sister sizing.
- Sister sizing works best when adjusting only one size up or down from your true size.
It’s important to remember that sister sizing is a tool for fine-tuning fit, not a substitute for finding your correct bra size through proper measurement and fitting. While it can be tempting to use sister sizes to buy a bra in an unavailable size, this should be done sparingly to ensure optimal support and comfort in your everyday bras.
US vs UK Sizing
US and UK bra sizing systems differ significantly, particularly in cup sizes beyond DD. Understanding these differences is crucial when converting between systems or finding sister sizes across countries. Here’s a comparison of US and UK bra sizes, including their sister size relationships:
US Size
UK Size
Sister Sizes (US/UK)
34D
34D
32DD/32DD, 36C/36C
34DD
34DD
32DDD/32E, 36D/36D
34DDD/F
34E
32G/32F, 36DD/36DD
34G
34F
32H/32FF, 36DDD/36E
34H
34FF
32I/32G, 36G/36F
34I
34G
32J/32GG, 36H/36FF
In the US system, cup sizes typically progress as A, B, C, D, DD, DDD (or F), G, H, I, and so on. The UK system, however, uses double letters after DD: A, B, C, D, DD, E, F, FF, G, GG, and so forth. This difference becomes more pronounced in larger cup sizes, where a US G cup is equivalent to a UK F cup.
When considering sister sizes, the principle remains the same in both systems: moving up a band size requires going down a cup size to maintain the same volume, and vice versa. However, it’s important to note that while the volume may be equivalent, the fit and shape can vary between sister sizes and across different sizing systems.
For example, a US 34DDD (UK 34E) has the following sister sizes:
- US: 32G, 36DD
- UK: 32F, 36DD
This equivalence allows for some flexibility when shopping across different brands or countries, but it’s crucial to remember that sister sizing works best when adjusting only one band size up or down from your true size.
When converting between US and UK sizes or finding sister sizes across these systems, always refer to a reliable conversion chart or consult with a professional fitter to ensure the best fit and support.
Cross-Sizing Between Brands
Cross-sizing between brands is an important concept to understand when shopping for bras, especially for those with fuller busts. Different brands may have slight variations in their sizing, which can affect how a bra fits even if it’s labeled as your usual size. Here’s a breakdown of cross-sizing considerations:
Brand Type
Sizing Characteristics
Cross-Sizing Tip
US Brands
Often use stretchier fabrics
May need to size down in band
UK Brands
Typically use firmer materials
May need to size up in band
European Brands
Use centimeter measurements
Convert to inches for US/UK equivalence
Australian Brands
Similar to UK sizing
Use UK size as a starting point
When cross-sizing between brands, it’s important to consider the following factors:
- Band firmness: Brands like Natori use softer, stretchier fabrics, resulting in a looser band fit compared to UK brands like Panache, which use firmer materials. You may need to adjust your band size accordingly.
- Cup construction: Some brands use different cup grading methods, which can affect how the cup fits across sizes. For example, a US G cup may fit differently than a UK F cup, even though they’re technically equivalent.
- Wire shape and width: Different brands use varying underwire shapes and widths, which can impact fit and comfort. A brand known for wider wires may require a different size than one with narrower wires.
- Fabric composition: The elasticity and strength of the materials used can affect how a bra fits and supports. Brands using power mesh or firmer elastics may provide a more secure fit in your usual size.
- Style variations: Plunge, balconette, and full-cup styles from the same brand may fit differently even in the same size. Always consider the bra style when cross-sizing.
When trying a new brand, it’s often helpful to order multiple sizes around your usual size to find the best fit. Remember that sister sizing can be useful when cross-sizing between brands, but it’s most effective when adjusting only one band size up or down.
Lastly, some brands like Curvy Kate provide both US and UK sizes on their website to help customers navigate the sizing differences. Always refer to brand-specific size charts and fitting guides when available to ensure the best possible fit across different brands.
