Keep mulch 2–3 inches off trunks and stems. A yard of mulch weighs 400–800 lbs — bulk deliveries need a driveway spot and a free afternoon with a wheelbarrow.
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The mulch math
cubic yards = sq ft × depth (inches) ÷ 324 bags (2 cu ft) = cubic yards × 13.5
The 324 comes from a cubic yard being 27 cubic feet and an inch being a twelfth of a foot — every mulch, soil, and compost question on earth reduces to this one formula with different depths plugged in.
A worked example
200 sq ft of beds at 3 inches: 1.85 cubic yards — call it 2 yards bulk ($90) or 25 bags ($100). At this size bulk already wins, and the gap widens fast: 400 sq ft is 4 yards bulk ($180) vs 50 bags ($200) — plus 50 trips from the car.
Getting the most from it
Weed and edge BEFORE mulching (mulch suppresses new weeds; it politely blankets existing ones), water the beds first, then spread to even depth with a rake. Around trees: a flat donut, not a volcano. The same ÷324 math prices out thetopsoil and compost jobs on your list — and your bed square footage subtracts from the lawn number in the lawn size calculator.
Frequently asked questions
How much mulch do I need?
Square feet of bed × depth in inches ÷ 324 = cubic yards. At the standard 3-inch depth, one cubic yard covers about 108 sq ft, and one 2-cubic-foot bag covers about 8. The calculator does the division and the bags-vs-bulk price math.
How deep should mulch be?
2–3 inches. Under 2 lets light through and weeds germinate; over 3–4 suffocates roots and sheds water like thatch. And keep it 2–3 inches away from trunks and stems — the 'mulch volcano' against a tree slowly kills the tree.
Bagged or bulk mulch — which is cheaper?
Bulk wins on price at volume: a cubic yard delivered runs $30–60 while the same yard in bags (13.5 of them) runs $45–90. Bags win under about a yard, or when you're moving it through a house to a courtyard. The break-even is usually around 1–2 yards — the calculator shows both numbers for your area.
How often does mulch need topping up?
Yearly for looks, every 2 years for function — organic mulch composts itself into the soil from the bottom (that's a feature). Rake the old layer to break crusting, then top up only what's needed to get back to 3 inches, which is usually about half a first-time application.