Mulch Calculator

Two to three inches suppresses weeds and holds moisture; one inch is decoration that weeds push straight through; four or more starves roots of oxygen and traps damp against stems. Volume is area × depth in feet, divided by 27 for cubic yards — so depth is the number that actually drives the size of your order.

At 3 inches deep that is 200 × 0.25 = 50 cubic feet, or 1.85 cubic yards. In bags it is 25 of the 2 cu ft size or 17 of the 3 cu ft size. The rule of thumb behind it: one cubic yard covers about 100 sq ft at 3 inches deep, or 160 sq ft at 2 inches.

Bags make sense below about one cubic yard, when you want consistent color, and when you have nowhere to dump a pile. Above a yard, bulk delivery is often half the price per yard and far less plastic to haul — but you need a spot on the driveway and a free weekend, since a yard of damp hardwood mulch weighs 800–1,000 lb and moves one wheelbarrow at a time.

Leave a 2–3 inch gap around trunks and crowns. Mulch piled against bark — the classic mulch volcano — holds moisture there, invites rot and borers, and gives voles a covered place to chew. Pull the ring back to the flare of the trunk, and never bury the graft union on a shrub or rose.

Organic mulches break down and settle roughly an inch a year, which is why an annual one-inch refresh maintains a 3-inch bed rather than adding to it. Before topping up, rake and fluff what's already there: old mulch often mats into a water-shedding crust, and breaking that up matters more than adding volume.