How to Measure Bra Size for Kids & Teenagers at Home

Parents often wonder how to choose the first bra for their kid. Well, the first bra stage is about helping your daughter feel comfortable, confident, and supported with the correct bra size. Learning how to measure bra size for kids makes the process easier.

A simple at-home method using a kids' bra size chart ensures a snug fit. While children’s bras often use youth sizes (XS–XL), older teens may shift to band-and-cup measurements. That’s where Plan B’s Training Bra Size Chart and Sports Bra Size Chart, come in handy. 

This article covers when your daughter needs a bra, how to measure, how to measure for a good-fitting bra, common mistakes, and FAQs.

When Will My Daughter Need Her First Bra?

Most girls need their first bras between the ages of 8 and 13, depending on their growth and comfort. However, if you’re unsure whether it's time to buy a bra, look for the following early signs:

• Breast budding: Development of breast tissues

• Tenderness: Soreness/sensitivity around the chest. 

• Nipple show-through: Their nipples may show through light T-shirts/crop tops. Thus, light coverage can help them feel more confident.

• Extra support during sports: Movement during P.E. or sports may feel uncomfortable without support.

Most parents start with a training bra that offers gentle support and a sports bra for active days. It’s important to reassess the bra size for teenagers from time to time due to growth spurts. Re-measure every 3–4 months or before a new school term to ensure the correct bra size for your kids. 

 

Explore options such as Plan B’s Training Bras and Trunk Sets for comfortable everyday styles.

How to Measure Bra Size for Kids and Teens Easily at Home

Learning how to measure bra size at home is straightforward since you only need to know the full bust and under bust size to find the right bra.

Things You Will Need

• Tools: Soft measuring tape or string/ribbon and ruler.

• Clothing: A non-padded camisole and a mirror.

• Posture & breath: Place their arms at their sides as they breathe naturally. Keep the tape parallel to the floor. 

Kids & Teen Bra Measurement: Step-by-step

Below is a step-by-step process on how to measure bra size for teenagers:  

• Step 1 - Find out the band (under bust size): Wrap the tape around the rib cage, under the bust. Note the number in inches/centimeters and round off to the nearest whole number.

• Step 2 -  Measure the fullest bust (Over bust size): Wrap around the fullest part of her chest. The tape should lie flat but not too tightly. Level it all around, and note the number. This measurement helps determine the right cup size/cup volume.

• Step 3 - Find size:

• Youth sizing: Most kids' bras, like non-wired bras and sports/tube bras, follow XS–XL sizing to determine the perfect bra size. After a considerable amount of research and customer surveys, Plan B has devised a sizing system based on the age of the child. 

• Band and cup size: Traditional bras, such as underwired or padded bras, use cup size. Bust size − Band size = Cup Size, where 1 inch = A, 2 inches = B, and so on. Check for alternative bra sizes too. They have the same cup volume but different band widths, allowing for better band fit. This system can get complicated for preteens who aren’t developed enough. 

• Fit check: A bra fits properly if there’s no band arching, tight hooks, and bra straps digging into the shoulders. Furthermore, there's smooth coverage under T-shirts with no gaping or spillage. Your daughter should be able to fit two fingers comfortably under the band. If there are red marks, the bra is too tight. 

Pro tip: Cross-check with Plan B’s Training Bra Size Guide and Sports/Tube Bra Size Chart for brand-specific mapping.

The image below shows sizes in inches and cms corresponding to the age range for kids and teenagers.

How to Measure Bra Size Without a Tape

Here’s how to measure a kid's bra size for a perfect fit without a soft tape measure:

• String/Ribbon size: Wrap a string/ribbon around the underbust, and mark the meeting point. Now lay it against a ruler and note the number. Repeat for fullest bust.

• Convert & size: Use these calculated sizes and check for the corresponding XS–XL or cup size.

Common Measuring Mistakes & Quick Fixes

Errors can lead to the wrong size and can result in neck and shoulder pain, bad posture, or irritation. Here’s how to avoid them with quick checks: 

• Tape pulled too tight or loose: Re-measure in a relaxed posture with the tape snug and level all around.

• Measuring over padded tops: Bulky layers add a few inches/centimeters. Measure over a non-padded layer, such as a light camisole, for an accurate kids' bra size.

• Ignoring brand charts: Sizing varies widely across brands. It’s best to cross-check with Plan B’s bra size charts to ensure the best fit.

• Not re-measuring after growth spurts: Body shape changes quickly during pre-teen and teenage years. So, re-measure every 3-4 months to ensure the right bra size for continued comfort.

Confident First Fit Starts at Home

Buying a new bra with the right fit starts at home with simple steps. Take quick underbust and overbust measurements and match them to a reliable kids bra size chart to avoid brand-to-brand variations. Re-check every 3-4 months to ensure that the bra fits correctly for consistent support and comfort. 

For starters, choose skin-friendly fabrics like premium cotton and look for details such as adjustable straps for a better fit. It is best to try the first bra at home and build confidence in a relaxed environment. Your daughters can swap between styles, like gentle coverage for daily wear, sport bras for active routines, or multiway styling bras as they grow. 

Come, explore Plan B’s collection of training bras, sports bras, and girls innerwear to lock in a comfy first fit for your young daughters! 

FAQs

How often should I re-check my teenage daughter’s bra size as she grows?

Every 3-4 months or before the start of a new school term. This helps to buy the right bra size from premium bra brands that feel snug.  

Which comes first, a training bra or a sports bra for teenagers?

Most girls start wearing a training bra first for gentle support. A sports bra becomes essential once they begin active routines or school sports.

When does a girl need a bra with cups vs. one without?

A cup-based bra works well for fuller breast development, gaping, or when more shape is needed. Before that, non-padded styles work well.

How do I measure my 10-year-old for a bra?

Use a soft tape for bust measurements (under bust and fullest bust), then map the numbers to a kids' bra size chart. Prioritise comfort over labels.