About this app
This app calculates Z-scores for testicular volume. Enter volume (in case of ultrasound: PI/6 x W x L x H), date of birth, date of observation, chose orchidometer or ultrasound, and click calculate! Lines in the graph represent -2, -1, 0, 1, and 2 SD scores. Designed by Sjoerd Joustra. Programmed by Marc Engelen. Data from Joustra et al, Acta Paediatrica, 2015. For more information: sjoerd.joustra@gmail.com
Latest release
What’s New
This app has been updated by Apple to prepare for watchOS 27 compatibility. No new features are included.
Audience growth
Ratings growth
Baseline captured. Growth appears after the crawler observes a changed rating count.
Momentum comes from crawler snapshots for the tracked storefront. “Viral growth signal” means unusually fast recent rating gains; it is an indicator, not download data.
Price tracking
Price intelligence
First snapshot captured. The trend line starts after the next crawler price observation.
- First observed Sep 1, 2026 · 2:06 PM Free
Screenshots
