For most trans men, testosterone will not make you noticeably taller. The key factor is whether your growth plates have fused, which typically happens around age 16 to 17 in people assigned female at birth. If you’ve already finished growing, testosterone cannot lengthen your bones, regardless of the dose or how long you take it. If you start testosterone while your growth plates are still open, some additional height is possible.
Why Growth Plates Matter More Than Hormones
Height is determined by the length of your long bones, and those bones grow from soft cartilage zones near their ends called growth plates. During puberty, sex hormones (both estrogen and testosterone) gradually cause these plates to harden and fuse into solid bone. Once that fusion is complete, no hormone can restart the process. In people assigned female at birth, the growth plates in the forearm typically close around age 16, with other bones following a similar timeline. By 18, most people have no remaining growth potential.
This is why the WPATH Standards of Care, Version 8, states plainly that sex hormone treatment will not affect height in postpubertal adolescents because bone maturation is already complete. The same applies to adults. Testosterone changes many things about your body, but vertical height after growth plate fusion is not one of them.
Starting Testosterone Before Growth Plates Close
If you begin testosterone while your growth plates are still open, you can gain height. A study published in The Journal of Clinical Endocrinology and Metabolism followed trans boys through treatment and found that even those with little remaining growth potential still gained an average of 2.5 cm (about 1 inch) during treatment, reaching a mean adult height of 169 cm (roughly 5’6″). Of the 85 subjects in this group, 82% grew at least 1 cm.
Trans boys who started treatment at an earlier pubertal stage ended up about 3 cm taller than those who started later. Their adult height also exceeded their predicted adult height by nearly 2 cm on average, meaning testosterone didn’t shortchange their growth. This counters an older concern that androgen therapy might cause bones to mature too quickly and cut growth short. Multiple controlled trials have shown that testosterone accelerates the rate of growth without advancing skeletal maturation fast enough to reduce final adult height.
The Role of Puberty Blockers
Some adolescents use puberty blockers (GnRH agonists) before starting testosterone. These medications pause estrogen-driven puberty, which delays growth plate fusion and keeps the window for vertical growth open longer. When testosterone is then introduced, it drives a growth spurt similar to what cisgender boys experience. The combination of blockers followed by testosterone generally results in a taller adult height compared to going through estrogen-driven puberty to completion and then starting testosterone afterward.
What Testosterone Does Change in Adults
Even though testosterone won’t lengthen your bones after fusion, it does reshape your body in ways that can subtly affect how tall you appear or feel. Increased muscle mass in the back, shoulders, and core can improve posture, and some trans men report standing a bit straighter after months on testosterone. This isn’t true skeletal growth, but it might add a centimeter or so in measured standing height if your posture was previously poor.
Testosterone also increases bone mineral density. A study of trans men on testosterone found a significant 7.8% increase in hip bone density over two years, with a smaller 3.1% increase at the spine. Denser bones are stronger bones, which matters for long-term skeletal health. But denser and thicker bones don’t translate into taller bones. The effect is similar to what happens with weight-bearing exercise: your skeleton gets more robust without getting longer.
Some trans men notice their shoes feel tighter after starting testosterone. This is likely related to soft tissue changes (thicker skin, increased muscle and connective tissue in the feet, and fluid shifts) rather than actual bone lengthening. The foot bones are fused just like the rest of the skeleton.
Realistic Height Expectations
If you’re an adult or a late teen whose growth is complete, your height on testosterone will be essentially the same as your height now. The average height for people assigned female at birth is around 5’4″ (163 cm), and most trans men will remain in that range. This can be a source of dysphoria, but it helps to know that plenty of cisgender men are also in the 5’3″ to 5’6″ range.
If you’re younger and still growing, the timing of treatment makes a real difference. Starting puberty blockers before or during early puberty, followed by testosterone, gives you the best chance of reaching a height closer to the male average. The earlier the intervention, the more growth potential remains. If you’re a teen wondering about this, a doctor can order a bone age X-ray, a simple hand and wrist scan that shows how much growth potential you have left. That single test gives you a much clearer answer than age alone, since growth plate fusion varies from person to person.
For those already past the window for vertical growth, the changes testosterone does bring (fat redistribution, muscle development, voice deepening, facial hair) tend to have a far greater impact on how you’re perceived than height does. Height is one dimension of a much larger physical picture that testosterone reshapes significantly.