So. I tend to not use store bought sauces, can’t give advice on that.
But, if you haven’t considered it, you can reduce your overall work load by making sauces in bulk, and then freezing them. I got myself some giant icecube-molds to freeze into 1/2 cup blocks, and then transfer them to sealed vacuum bags.
Simply thaw and reheat for use. This also works quite well for stocks, or anything that takes hours of simmering.
for the record, you also need to consider the height. [height] * pi * [radius]^2 = v.
it should also be noted that two 6 inch pizzas are smaller by area and volume than an otherwise similar 10 inch pizza (the combined area of 2 6 inch pizzas are 226.19 in^2, verses 314.15 in^2 for a 10 inch.)