4 feet by 6 feet 8 feet tall. When you get the mylar up it's hard to tell. I wish I could of made it bigger but that's what I had to work with it's in a small tool shed away from my house. The lights look close but you can almost touch them without burning your hand. I got AC blowing right across them. My ballast are in there with a dehumidifier that would do my house. I'm middle east coast US. A big problem with humidity,great for vegging but sucks for flowering. I light at night so I can go in there after work and it keeps them just warm enough when it gets cold. All I need now is co2. Tried everyway I could think of but it looks like tanks. Having a flame in there scares me. Any way thanks for asking. I will show more of my next grow.