You would need:
1) 16.88 lb for 0.5 in (fine sand)
2) 13.12 lb for 0.5 in (medium sand)
3) 33.75 lb for 1 in (fine sand)
4) 26.25 lb for 1 in (medium sand)
This is per CaribSea's calculator. Fine is defined as 90 lb/cubic foot; medium is 70 lb/cubic foot.
One 20 lb bag of their Moonlight sand fully covered my 50 gal tank at around 0.5 in. My tank has about the same footprint as yours. However, I later added 20 lb of Activ-Flora because I wanted plants, and needed a deeper layer of substrate.
I think you will just need one 20 lb bag.