How much does 1 sq meter of fiber glass weigh?

Question

average thickness (normal cloth, not Robin) and not too much resin.

Would it weigh more than 1 sq/m of a Caliber 22 aluminium sheet?

Answer 1

what is the thickness?

no thickness, no weight calculation possible.

measure it!

If it comes on a roll count the number of layers, measure the total and divide.

Answer 2

The reason that this question is so tough to answer is that the cloth you mention will weigh so much less, compared to the weight of the resin used.  You say that you will use "not too much resin", but that will be the largest determinant of the final weight of the sheet.

If you are able to get away with using about 800 ml. of resin, you will have a sheet that is under 1 kg.

If it is a 22 ga. aluminum sheet you are referring to, that should weigh just about 1.75 kg.