I have not had success in accurately being able to measure loose wood. I've hauled wood to my house loose and it's varied quite a bit, like total load being anywhere from 1 to almost 1.5 cords.
I know 2 of my compete tors sell it loose and I've heard many complaints about being shorted. One for example has a 4x8x10ft bed and somehow figures that it's 2 cords, where it's more around 1.75 cords.
I've actually had several of his old customers call me back after I delivered to ask if I gave them a bunch of extra wood, their shed/rack/basement, etc was packed full and still had more wood.
Believe me I've tried to figure a way of not stacking. Short of selling by weight, I don't know a way. (Truck scales areally very expensive BTW)