Volume of concrete in a slab of uniform thickness is calculated by multiplying the length in feet x the width in feet x the thickness in feet and dividing by 27 ( the number of cubic feet in a cubic yard). For your project 16'x10'x.333'=53.28 cubic feet 53.28 cubic feet divided by 27 cubic feet /cubic yard=1.97333 cubic yards, rounded off equals 2 cubic yards of concrete.
Concrete blocks with the mortar would be 16" in length. A pad 16'x10' would be 12 blocks long x 7.5 blocks wide .

Are you considering using a slab instead of block walls for a foundation?

If so, you may need to consider the frost depth in your area in comparing prices. Most places, you need to go deeper with your foundation than the most extreme depth to which the ground will freeze. If you don't do so, your foundation will move with the ground freeze/thaw cycles.

Probably not an issue with RR ties (unless you have glass glazing), but the movement will definitely crack block or a slab foundations. And will make the GH structure attached to them move too, which may cause doors not to open, or break brittle glazing, like glass.

Most slabs are poured with a thicker perimeter, say 8" wide or so which goes down to the frost line. Usually some rebar is put in as well. There are also potentially other requirement in various areas depending upon your soil types and ground moisture, etc.

If you were just doing a block wall foundation, you typically would still need to dig them down below the frost line, and pour a footing for them (a concrete ledge, usually 16" wide and 8" deep with rebar), and then set them on that footing. (I said this poorly, it is the bottom of the footing which needs to be below frost line).

Unless you are in a temp zone where ground freezing isn't an issue, you should investigate the frost line depth in your area. And other foundation practices there too. They may not be needed for a simple (and flexible) GH, but always good to know how things are being done in your area, so you can decide how much to do for your project.

Thank both of you. i didnt consider the frost line. Im in Nw Alabama, so we may have a light winter for a few years and then a hard winter.