HMP Isle of Wight is currently holding more prisoners than it was designed to, according to Ministry of Justice statistics.
The facility, which combines the former HMP's Albany, Camp Hill, and Parkhurst, was designed to hold 1,550 prisoners, but currently has 1,590 - 40 more than capacity.
A Ministry of Justice spokesperson told Isle of Wight Radio that the prison is still able to operate safely
It's claimed around two thirds of jails in England and Wales are operating at an overcrowded level.
The Prison Reform Trust says there are nearly seven-thousand-three-hundred more people in the system than there should be.