Im making 3 raised beds they are 40 inches on all 4 sides and 11 inches tall i read online to do a 60% topsoil 30% compost and 10% potting soil mix i was just wondering if someone can help me calculate how many bags of each i will need to fill them approx. i already have been growing in 5 gallon buckets that contain mostly potting soil with compost mixed in so i would like to use that up if i could for the potting soil

40x40"x11" is just a bit over 10 cu/ft. So you'd want 6cu/ft of topsoil, 3 cu/ft of compost and 1 cu/ft of potting soil per bed.

Looks like local box stores sell .75 cu/ft bags, so 8-9 (40lb) bags of topsoil, 3-4 (40lb) bags of compost, and 1-2 (40lb) bags of potting soil would be what I'd buy- ( per raised bed that is)

You could dump the buckets in the bottom, and level it out, and measure the remaining depth. If you need 5-6 more inches to fill the beds, just cut the above quantities in half.

Never hurts to have extra dirt, it doesn't really expire