How much marinara sauce would you need for 525 1" meatballs, if you were making them for meatball subs?
I think this would just boil down to basic math. Find a recipe for meatball subs, divide the the number of meatballs into 525, get your total. And then increase the sauce items by the total. There are programs on the net that will increase recipes.
I made 144 1" meatballs for a buffet this weekend and used 4-28 oz cans of tomato sauce, 1 cup of red wine & the assorted spices and seasonings of choice. We had plenty of sauce for the meatballs and they easily could've been put on bread for a sub, which is what we're doing with the leftovers this week. Hope that this gives you a starting point. Have fun simmering :)
a lot is going to depend on if your meatballs sit overnight in the sauce (they absorb); the size of your meatballs; the amount of bread in your meatballs; how saucy you want your finished product, etc.