A science-backed estimate of your child's adult height and biological maturity stage — with training guidance for their stage of development.
The original researchers recommend the present parent estimate the absent parent's height — reported heights work reasonably well. As a last resort you may use Australian averages (male ~175 cm, female ~162 cm), but this will reduce accuracy.
Peak Height Velocity and Mirwald maturity offset answer a different question from adult-height estimation. To keep this calculator simple, that assessment is now a separate Youth OS module.
Open Module 02 — Growth Spurt & PHV →During the spurt, long bones lengthen faster than the muscles and tendons attached to them can adapt. The muscle-tendon unit is effectively stretched taut across a lengthening frame — flexibility drops, and tension rises at the points where tendons anchor into bone.
In an adult, that anchor is solid bone. In a growing child it is an apophysis — an active growth plate. It is softer than the tendon pulling on it, so under repeated load the bone gives before the tendon does. That is what produces the classic growing-athlete injuries:
Osgood-Schlatter — the patellar tendon pulling on the shin bone, just below the knee.
Sever's disease — the Achilles pulling on the heel bone.
Sinding-Larsen-Johansson — the tendon at the bottom of the kneecap.
Bone lengthens before it fully mineralises. There is a window where the skeleton is longer but not yet as strong, and the growth plates are especially vulnerable to shearing and twisting forces — the exact loads in cutting, landing and pivoting sports.
Limb lengths change faster than the nervous system can recalibrate. Motor control and balance temporarily get worse, starting around six months before peak growth. Landing mechanics degrade at exactly the moment the levers are longest and the body is heaviest. Encouragingly, the research suggests staying in structured training limits this dip — the answer is smarter training, not stopping.
In girls, hormonal changes increase joint laxity, which is linked to more knee and ankle injuries. In boys, rising testosterone is associated with a more aggressive, impulsive playing style — part of the added risk is behavioural, not just structural.
Don't stop. Adjust. Trim volume and high-impact load through the window, protect sleep and food, keep technical and strength work going, and take new knee or heel pain seriously rather than coaching through it. Then rebuild load as the spurt passes.
How strong is this evidence? The biological mechanism is well established. The injury statistics are suggestive but not settled — a 2025 systematic review of youth football found injury burden highest around peak growth in five of eight studies, and consistently lowest before the spurt, but graded the overall certainty of evidence as very low. Read this as a well-founded reason for caution, not as a proven law. Note also that this app's %PAH bands mirror how that literature defines the risk window (circa-PHV ≈ 88–93% of predicted adult height).
A statistical estimate — not a diagnosis, not a guarantee, and not a substitute for a GP or paediatrician. Khamis-Roche method (Pediatrics 1994;94:504–507). If you have any concern about your child's growth, speak to a doctor.