The quantity of epoxy, polyester laminating resin, or polyester finishing resin needed to completely wet out fiberglass reinforcement fabric is dependent on the weight of the fiberglass cloth.
Fiberglass chopped strand mat (CSM) is rated in ounces per square foot. To saturate it, you'll need an amount of resin that's two times the weight of the mat.
Example: 1.5 oz. of CSM needs 3 oz. of resin per square foot.
Fiberglass cloth is rated in ounces per square yard. One gallon of resin will wet out 60 oz. of fiberglass cloth.
Examples:
4 oz. fiberglass cloth  -  Takes 1 gallon of resin to wet out 15 square yards
6 oz. fiberglass cloth  -  Takes 1 gallon of resin to wet out 10 square yards
10 oz, fiberglass cloth - Takes 1 gallon of resin to wet out 6.5 square yards
Biaxial fiberglass cloth is rated in ounces per square yard and requires 3 times its weight in resin.
Example: The weight of 1708 biaxial fiberglass cloth is 17 ounces per square yard. It takes 51 ounces of resin, per square yard, to saturate it.