Your recipe makes 4 servings but you need to make 7? Or does it make enough for an 11" x 7" pan and your pan is 9" x 9"?
Or say you know that you need 2/3 of a recipe... just what IS 2/3 of 1-3/4 cups? Or of 4 Tbs?
Recipe Elf makes it easy to find out. First enter the amount that the recipe makes and the amount that you want to make, and then for all of the ingredients you can just dial in the called-for amount and read how much you should use.
Recipe Elf lists several different ways to make the resulting amounts. For instance, it will tell you that 2/3 of 1-3/4 cups is 9.33 fl oz, and that you can make that by using 1 cup + 1 Tbs + 2 tsp ...or that 1 cup + 2-1/2 Tbs is about 1% too little (almost certainly close enough) ...or that 1-1/4 cup is 7% too much (maybe OK, too.)
Like most elves Recipe Elf is small, quick, and really good at just one thing: scaling measurements of volume used in a kitchen. It knows about fluid oz, ml, tsp, Tbs and cups, but can't tell you how many cups are in a pound of sugar.
Give it a try.