How do I estimate how many yards of topsoil I need for a lawn? How do I estimate how many yards of mulch I need for garden beds?

Measure the length and width of the area that you need to cover and multiply those together. This will give you the area

Figure out the thickness of the mulch/topsoil that you need and multiply this times the area that you calculated above. This will give you the volume of material that you need to buy. For simplicity, all of your measurements should be in feet.

One cubic yard equals 27 cubic feet, so divide your volume by 27 to get cubic yards