Mulch is deceptively bulky — a bed that looks small can swallow a dozen bags, and a full-sun bed breaks down faster than most people expect, so "how much did I buy last time" is a bad way to plan a refresh. This calculator converts your area and depth into cubic yards, cubic feet, and tons, using a supplier-sourced density instead of a rounded-off average. Enter the length and width of your bed, pick a depth — or tap a preset for a refresh, a standard bed, or a new bed — and the results update as you type. Add a price per yard or ton and you'll get an estimated cost range too. Whether you're topping off an existing bed or establishing a new one, the numbers below are the ones to bring to the garden center or supplier.
Enter your dimensions above to see results.
The calculator first finds the volume of the area in cubic feet: length (ft) × width (ft) × depth (in ÷ 12). That's converted to cubic yards by dividing by 27, since a cubic yard is 3 ft × 3 ft × 3 ft. A waste percentage is added on top to cover spillage and an uneven bed surface, and the adjusted cubic yardage is multiplied by mulch's density (tons per cubic yard) to get the weight in tons. Bag counts divide the adjusted cubic feet by each bag's yield; truckloads divide the adjusted cubic yards by the truck's capacity.
A 10 ft × 10 ft bed at 3 inches deep: volume = 10 × 10 × (3 ÷ 12) = 25 cubic feet. In cubic yards, that's 25 ÷ 27 = 0.93 yd³. Adding a 10% waste factor: 0.93 × 1.10 = 1.02 yd³. At 0.30 tons per cubic yard, that's 1.02 × 0.30 = 0.31 tons — or 0.20–0.51 tons across the full 0.20–0.50 density range, since mulch's weight swings more than any other material here depending on species and moisture. In 2 cu ft bags, the adjusted 27.5 cu ft (25 × 1.10) needs 14 bags.
Mulch depth depends on whether you're maintaining an existing bed or building a new one, and going too deep causes real problems rather than just wasting material. A 2" refresh layer is right for a bed that already has mulch down — most of the prior application is still there, just broken down, so you're topping it off rather than starting over. 3" is the standard depth most landscapers default to for an established bed, deep enough to suppress weeds and hold moisture without smothering roots. 4" suits a brand-new bed that needs a head start on weed suppression while plants establish. Avoid going meaningfully past 4" anywhere, and always keep mulch pulled back a few inches from tree trunks and plant stems — piling it up against a trunk (a "mulch volcano") traps moisture against the bark and invites rot, fungus, and pests, regardless of how deep the rest of the bed is.
| Type | Dry (lbs/yd³) | Wet (lbs/yd³) |
|---|---|---|
| Shredded hardwood | 500–700 | 800–1,000+ |
| Cedar | 400–600 | 700–900 |
| Pine bark nuggets | 350–500 | 600–800 |
| Rubber | 800–1,200 | 800–1,200 |
| Compost / leaf mulch | 600–1,000 | 1,000–1,400+ |
| Straw | 350–500 | 900–1,400+ |
Mulch varies more than any other material on this site, because the product itself differs by species and processing, and because it absorbs water readily. Best Bark Mulch, a bulk mulch supplier, puts a cubic yard of wood mulch at 400–800 lbs dry and over 1,000 lbs after rain, with roughly 600 lbs (0.30 tons) per yard as the working estimate for typical hardwood. North Bay Materials lists mulch/bark more broadly at 0.50–0.70 tons/yd³. Rained-on hardwood can weigh 30–50% more than the same material dry — rubber mulch is the exception and doesn't change with moisture. The published 0.20–0.50 ton/yd³ range spans dry pine bark nuggets at the low end to wet hardwood at the high end; see the weight-by-type table below for specifics. We use 0.3 tons/yd³ as the display figure, drawn from:
Read more in our density methodology.