vloglady,
If you need to know the volume of a square or rectangle pan, measure and multiply length x width x height.
To calculate the volume of a circular pan (a cylindrical shape)
go here.
If you visit each link, you will find that they are not all the same, they provide different sized pans:
fantes: 4" x 13.5
Sweet Celebrations: ~10 x 7,~ 8 x 8
kitchengadgetscentral: don't know, looks big like ~8" x 11"
cooking.com: 14 x 4.5
bakedeco: 8" x 11 1/4" x 1"