Mulch Calculator: Bags to Buy, Cubic Yards & Total Cost
Turn your bed size, mulch depth, and bag size into the cubic yards and bags to buy, plus an estimated cost at your local price.
Inputs
ft ×
ft
in
$
Results update as you type — no submit
ResultsLIVE
Bags to buy
15
Volume
1.1 cu yd
= 30 cu ft ≈ 0.85 m³
Volume1.1 cu yd ≈ 0.85 m³
Estimated cost @ $4.50/bag$67.50
Formula
volume = 10 × 12 × (3 ÷ 12) = 30 cu ft = 1.1 cu yd
bags = ceil(30 ÷ 2) = 15
bags = ceil(30 ÷ 2) = 15
MeasureShedmeasureshed.com/calculator/mulch-calculator
Mulch — material listUNITS: FT · SCALE: NTS
Inputs
Bed size10 × 12 ft
Depth3″
Bag size2 cu ft
Price per bag$4.50
Results
Bags to buy15
Volume1.1 cu yd (30 cu ft)
Estimated cost$67.50
Shopping list
☐ 15 × 2 cu ft bags of mulch
Formula
volume = 10 × 12 × (3 ÷ 12) = 30 cu ft = 1.1 cu yd
bags = ceil(30 ÷ 2) = 15
cost = 15 × $4.50 = $67.50
How it works
Mulch is sold by volume, so the math is bed length × width × depth. The only trap is units: depth is measured in inches while the bed is measured in feet, so the calculator divides the depth by 12 before multiplying. That gives cubic feet; dividing by 27 converts to cubic yards, which is how bulk mulch is quoted.
Bags always round up to the next whole bag — you can't buy four-fifths of a bag. The cost estimate multiplies the rounded bag count by your price per bag, so it matches what the register will actually charge.
Worked example
Bed 10 ft × 12 ft · depth 3″ · 2 cu ft bags @ $4.50
volume = 10 × 12 × (3 ÷ 12) = 30 cu ft = 1.1 cu yd
bags = ceil(30 ÷ 2) = 15 → cost = 15 × $4.50 = $67.50
volume = 10 × 12 × (3 ÷ 12) = 30 cu ft = 1.1 cu yd
bags = ceil(30 ÷ 2) = 15 → cost = 15 × $4.50 = $67.50
Questions from the yard
2–3 in for beds; 3–4 in for weed suppression around trees. Keep it off trunks and stems.
Bulk usually wins past about 1 cu yd — roughly 14 two-cubic-foot bags. Below that, bags come out ahead once you add a delivery fee, and they're far easier to carry to a back yard.
A cubic yard is 27 cu ft, so it takes 14 two-cubic-foot bags or 9 three-cubic-foot bags to cover the same ground — rounding up in both cases.
Directly. One cubic yard covers about 108 sq ft at 3 in deep, 162 sq ft at 2 in, and only 81 sq ft at 4 in — halve the depth and you double the coverage.
SOURCES — NIST Guide to the SI (Special Publication 811), Appendix B.8: Factors for Units Listed Alphabetically (the definitions behind every conversion on this page: 1 in = 2.54 E-02 m, 1 ft = 3.048 E-01 m, 1 yd = 9.144 E-01 m, printed in boldface, which the table's key defines as exact. NIST lists the volume factors rounded to seven digits (1 ft³ = 2.831 685 E-02 m³, 1 yd³ = 7.645 549 E-01 m³) and does not mark those exact; this calculator uses the exact cubes of the linear definitions, 0.3048³ and 0.9144³, from which 1 cubic yard is exactly 27 cubic feet.) · International Society of Arboriculture, Proper Mulching Techniques (©2021, v02.2021) ("The recommended mulching depth is 2–4 inches (5–10 cm)"; fine mulches such as composted materials go in a 2–3 inch layer and coarse mulches such as arborist wood chips in a 3–4 inch layer, applied "near, but not touching, the trunk".) · Colorado State University Extension, CMG GardenNotes #245: Mulching (revised December 2015, reviewed April 2023) ("In order to suppress weed growth, wood chip, gravel, grass clipping, and other mulch should be four inches deep. More is not better, though!", and "Keep the mulch back at least six inches from the trunk".)
Estimates for planning only — verify before purchase