How much mulch or soil do you need?
2–3″ for established beds; new beds up to 4″. More than 4″ can suffocate roots.
Worked examples: what common beds actually need
The numbers below use the same formula as the calculator: area in square feet, times depth in feet, divided by 27 to get cubic yards. They include no waste cushion, so add 5 to 10 percent when you order.
| Front foundation bed, 20 ft by 4 ft at 3 inches | 0.74 cubic yards, about 10 bags of 2 cu ft |
| Backyard border, 30 ft by 3 ft at 3 inches | 0.83 cubic yards, about 12 bags |
| Tree ring, 6 ft diameter circle at 3 inches | 0.26 cubic yards, about 4 bags |
| Raised vegetable bed top-up, 8 ft by 4 ft at 2 inches of compost | 0.20 cubic yards, about 3 bags |
| Whole front yard refresh, 500 sq ft at 3 inches | 4.63 cubic yards, about 63 bags |
That last example is the one that changes the buying decision. At a typical $4 per 2 cu ft bag, 63 bags cost about $252 and fill a car several times over. The same 4.63 yards in bulk at $45 per yard delivered is about $208 before any delivery fee, and it arrives in one drop. Below about 1 yard, bags are usually simpler and cheaper once delivery is counted. Between 1 and 3 yards, compare your local delivery fee carefully. Above 3 yards, bulk almost always wins on price and on labor.
Choosing depth by planting, not by habit
Established shrubs and perennials do well at 2 to 3 inches. New beds over bare soil can take 3 to 4 inches in the first year because the material settles and begins to break down. Annual flowers need only about 2 inches, kept away from the stems. Vegetable beds do better with 1 to 2 inches of compost or aged mulch than with a thick layer of fresh bark, because fresh wood ties up nitrogen at the soil surface while it decomposes. Around trees, hold the layer at 2 to 3 inches and pull it back 3 to 6 inches from the trunk so the root flare stays visible.
Topsoil and compost are not mulch with a different label
Topsoil is for filling and grading, not for covering beds. A low spot that is 10 ft by 10 ft and 3 inches deep needs about 0.93 cubic yards, roughly a full bulk yard once settling is counted. Compost is a soil amendment: work a 1 to 2 inch layer into a new bed, or lay about 1 inch on top of an established bed in spring. Ordering mulch math for a grading job, or topsoil math for a bed covering job, is the most common reason homeowners end up a yard short or a yard long. Run each material as its own calculation.
Ordering checklist
Measure each bed separately and add the volumes together, rather than guessing a yardage for the whole yard. Note whether your supplier sells by the cubic yard, by the scoop, or by the ton, and confirm a scoop is actually a yard. Ask whether the delivery fee is included in the per-yard price in the calculator. Pick a drop spot the truck can reach that is not on a septic field or a soft lawn after rain. Finally, order the 5 to 10 percent cushion: a spare bag can be returned or stored, a bare patch in July cannot be fixed at the same price.
Content reviewed October 2026. Prices in the examples are planning figures, not quotes; enter your local bag and bulk prices above for a real comparison.