Average penis size study reveals SAME results as previous research Average penis size remains at 5.57 inches (that's roughly half an inch shorter than the average $20 bill) The latest research into the average penis size has yielded some interesting results. The results, published this week, held few new surprises - the average penis size remains at 5.57 inches (that's roughly half an inch shorter than a $20 bill). However what the study did reveal was that men appear to tell the truth about the size of their manhood when it comes to the important business of scientific research. Measuring up: A new study on average penis size appears to show that men did not lie about their manhood The study, conducted by Dr Debby Herbenick at Indiana University, asked 1,661 men in the U.S. to give the size of their penis. Researchers were not involved in the measuring, rather left this practical aspect to each individual. Dr Herbenick told Psychology Today that she trusted men to give accurate measurements - as the study was part of broader research into condom sizes. She added: ' If they reported a bigger-than-reality size to us, they would get a baggier condom. If they reported a smaller-than-reality size to us, the condom would be too tight. Size matters: The average penis size remains at 5.57 inches (that's roughly half an inch shorter than a $20 bill) Other interesting outcomes of the study included the varying lengths - from 1.5 inches to just over 10 inches. Scientists also found that the size of the erect penis varied depending on how it was achieved. Oral sex proved more arousing than masturbation or being stimulated only by sexual fantasies. Dr Herbenick told the magazine that she would like to see more research conducted into the size of female genitalia to encourage women to think more positively about their bodies. The scientist is co-Director of the Center for Sexual Health Promotion at Indiana University School of Public Health-Bloomington and also works as a sexual health expert at The Kinsey Institute for Research in Sex, Gender and Reproduction. In the name of science Dr Debby Herbenick, who conducted the study at Indiana University, said she trusted men to give accurate measurements