Prince William appears eight years older than his real age because of his hair loss, according to a new Crown Clinic survey.
The heir to the throne has the looks of a 42-year-old man even though he is only 34.
That is because balding ages men more quickly than any other physical trait - putting up to eight years on the age of sufferers.
The second fastest ageing factor is greying hair which puts seven years on the age of the average man.
It means a silver-haired star like George Clooney would look 48 rather than his real age of 55 if he were to start dying his hair.
The third fastest ageing trait is having a full beard - which puts five years on the age of men.
So 41-year-old David Beckham would look 36 if he were to have a shave.
The fourth biggest ageing factor was having a goatee which ages men by four years.
Hollywood actor Leonardo DiCaprio looks 37 when he is clean shaven but his real age of 41 when he is sporting a goatee.
The fifth biggest ageing factor is being heavily unshaven, like Simon Cowell on the X Factor, which ages men by three years.
So Cowell would look 54 if he shaved rather than his real (unshaven) age of 57.
The findings came from survey of 1,000 people by Crown Clinic in Manchester, Britain's leading hair transplant centre.
Other ageing factors include being overweight, having man boobs and sporting a moustache, which all age men by an average of two years.
England football captain Wayne Rooney is 31 but would have the looks of a 39-year-old if he had not take steps to address his baldness.
Hair transplant surgeon Asim Shahmalak from Crown Clinic said: "Nothing ages a man faster than losing his hair.
"Prince William was one of the most desirable men in the world when he was in his early 20s but he has aged fast because he has done nothing to remedy the Windsors' strong baldness gene which has also affected his father and his grandfather.
"Wayne Rooney has turned back the clock very successfully by having two hair transplants. Just image how much less attractive he would look to sponsors if had let nature take its course and and now had the looks of a 39-year-old man. I am sure it has also helped to prolong his football career because he looks younger and fresher with hair."
Dr Shahmalak is Britain's leading hair transplant surgeon and his celebrity clients include model Calum Best, TV doctor Christian Jessen and Chris Steed, star of Gogglebox. Calum and Chris had FUE (follicular unit extraction) procedures at Crown Clinic while Christian Jessen opted for the more traditional FUT (follicular unit transplantation) method.
He has seen a 25% rise in young men seeking hair transplants since Rooney had his first procedure five years ago.
How balding ages men With hair Without hair (real age)
1 Prince William 34 42
2 Jude Law 35 43
3 Jason Statham 41 49
4 Woody Harrelson 47 55
5 Bruce Willis 53 61