The Tanner Scale addresses the maturity stages that occur throughout puberty. 



Breast development has on onset of 3-6 months and plateaus around the second year. When discussing breast development, it is often referred to by their respective stage on the Tanner Scale (view the context bar below). Typically, individuals undergoing feminizing hormone therapy will have breast development up until Tanner Stages 3 or 4, with a breast cup size ranging from a "AA" to "B". Complete breast maturity may not occur with hormone therapy alone and you may consider breast augmentation surgery if the effects are not what you desired.

There are also many online calculators for measuring breast cup size, such as one from Bare Necessities here.

Anatomy & Orientation

Before Therapy, Tanner 1

The illustration above depicts mature anatomy of the biological male, post puberty. If you are transitioning after puberty, this process will be referred to as your "second puberty". Thus, Tanner 1 will be in reference to your physique before the start of transitioning.

Scroll down to see illustrations of the Tanner Scale in reference to breast anatomy & development. 


Tanner 1


Budding Stage

Tanner 2

Breast Elevation

& Areolar Changes

Tanner 3

Areolar Elevation & Breast Fullness

Tanner 4

Mature Female Breast

Tanner 5

You can find a PDF from Vermont Department of Health that further outlines the Tanner Scale here.

Breast Changes Over a Timeline

Surface Anatomy

3-6 Months, Tanner 2

1 Year, Tanner 3

2-3 Years, Tanner 4

  • Budding Stage

  • Fat Collects around Areola

  • Sensitive Bumps on Areola

  • Rise of Papilla


  • Underlying Breast Tissue Development

  • Increased Areolar Diameter

  • Chest Hair Thinning

  • Papilla Elevation

  • Areolar Mound Develops

  • Further Papilla Elevation

  • Chest Hair Thinning

  • Increased Breast Fullness

Over the first six months, you may find changes to your areolas and a slight increase in fat around this area. This is known as the “budding” stage, as the first stage in breast maturity. The illustrations of the breast longitudinal section anatomy (seen below) at Tanner 2 Stage provide insight to what is happening beneath your breasts at this stage. Your glandular tissue is starting to develop as well as small lobules illustrated in purple. These lobules are involved in lactation, or breast milk production. Your areolas will develop small bumps around them, which may become more sensitive and painful to touch. Pain should resolve over several months, although you may find that your nipples remain sensitive. Over the course of two years, they should continue to grow and may even seem uneven (which is normal).

Over time, you could expect your breasts to continue onto Tanner Stages 3 or 4. As your breasts enlarge, your lobules will continue to proliferate as your glandular tissue further develops. Because of the development of glandular mammary tissue, it is possible that you will have the ability to breastfeed. Although this hasn’t been widely studied, few reports  of this occurrence have been made.

Your glandular tissue are the glands and ducts that are involved in transporting breast milk, such as the lactiferous ducts & sinus. They are both identified in the cross sections below.

Lobules are sac-like pouches where breast milk is drained into from milk-producing cells that surround them. The lobules are the purple sacs illustrated in the longitudinal section breast anatomy below.

Lactation is breast milk production. 


It is important to remember that the level of breast maturity that you achieve is individual to you and reliant on genetics.

Anatomy & Orientation

Longitudinal Breast Anatomy, Tanner 4

Lactiferous Sinus
Lactiferous Ducts
Mammary Lobules
Pectoralis Maj.

The illustration to the left depicts a longitudinal section of breast anatomy at Tanner 4. Here you can see the muscles behind the breast, including the pectoralis major (your "pecs"). Suspensory ligaments are illustrated as the white fibers spanning the width of the breast. Most importantly, you can see the mammary glandular tissue illustrated in purple, The mammary lobules collect breast milk which then travel down the ducts, drain into the sinus and exit out through the papilla.

Suspensory Ligaments are the fibrous ligaments that hold your breast tissue upright.

A longitudinal section is a cut plane of anatomy along the long axis of the structure.


Anatomy & Orientation

Longitudinal Breast Anatomy

Subcutaneous Fat
Glandular Tissue
Suspensory Ligaments

3-6 Months, Tanner 2

1 Year, Tanner 3

2-3 Years, Tanner 4

Before Therapy, Tanner 1

  • Minimal Glandular Tissue

  • Subcutaneous Fat Dominates the Breast


  • "Budding Stage"

  • Development of Glandular Tissue

  • Continued Glandular Tissue Development

  • Areolar Diameter Increase

  • Elevation of Areola

  • Breast Tissue Almost Developed Completely

© 2019 Sam Nigro, Augusta University

Hormone therapy is not required for any transition or queer experience. Changes from hormone therapy that are outlined in this website are not guaranteed. All changes from hormone therapy are dependent on genetic makeup and can be different for everyone. 

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