Pooled erect length averaged 13.93 cm across 55,761 men. Erect length rose significantly over time across regions and age groups. Increase persisted after adjusting for region, age, and population. Erect length grew from 12.27 cm in 1992 to 15.23 cm in 2021. No temporal trends in flaccid or stretched length. Significant geographic differences with sub-Saharan Africans longest. Europeans, South Asians, North Africans intermediate in length. East Asians shortest penile lengths. Increase observed in Asia and Europe separately. Trend held in urology patients and volunteers. Measurements consistent regardless of erection technique. Heterogeneity high but publication bias absent for erect length. Stretched length unreliable due to variable clinician force. Flaccid length poor predictor of erect size. Earlier puberty linked to longer penises. Environmental exposures speculated as cause.