MATERIALFOREMAN · SHEET M-001 · LANDSCAPE WORKS
CALC-001 · DRAWING NO. M-001 · REV A

Mulch calculator.

Drafted to scale · cited sources · honest numbers

Enter the bed dimensions and depth. The calculator returns cubic yards, bag count, and cost for both bulk delivery and bagged mulch. Fires a hard warning when depth exceeds 4 inches (the tree-killing mulch-volcano threshold).

◈ DRAFTING PANEL · MULCH TAKEOFF · N.T.S. SHEET M-001 · REV A
Redline · scope notice Landscape mulch only (shredded wood, bark, hardwood). Does not compute playground surfacing to ASTM F1292 critical fall height. Rubber mulch and decorative rock have different volumes per bag and are not covered.
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Note 01 · Field Procedure

How to measure the bed

  1. Measure the longest dimension of the bed in each direction. For curved beds, approximate with the smallest rectangle that contains the shape, then subtract roughly 20% for the curves.
  2. Decide on depth before ordering. New beds: 3 in. Refreshing existing mulch: 1.5-2 in. over what remains. Adding more than 4 in. total depth risks crown rot on trees and shrubs.
  3. Check existing mulch depth with a ruler pushed to the soil line. Subtract that from the target depth. Over-mulching year after year is the #1 cause of landscape plant decline.
  4. Keep a 3-6 in. gap between mulch and tree trunks, foundation walls, and wood siding. Mulch piled against wood accelerates rot and invites termites.
Note 02 · Equation

The formula

yd³  =  L × W × d  ÷  324  ×  ( 1 + waste ÷ 100 )
Lbed length in feet
Wbed width in feet
dmulch depth in inches
324ft²·in → yd³ factor (12 × 27)
Note 03 · Sanity Ranges

Mulch by project size

T Use case Notes
50 sfTree ring3 in. depth: ~0.5 yd³, 7 bags (2 cu ft). One wheelbarrow load.
100 sfSmall bed3 in. depth: ~0.9 yd³, 13 bags. One bulk-delivery minimum.
200 sfFoundation planting3 in. depth: ~1.9 yd³, 25 bags. Bulk delivery is cheaper above 2 yd³.
500 sfLarge landscape3 in. depth: ~4.6 yd³, 63 bags. Bagged at this volume costs 2-3x bulk.
1000+ sfFull property3 in. depth: ~9.3 yd³. Always bulk at this scale.
Note 04 · References

Sources

Authorities cited on this sheet
  1. Clemson University HGIC 1604: Mulch · Clemson Cooperative Extension. Recommends wood and bark mulches at 2 to 3 in. depth and advises keeping mulch 2 to 3 in. away from the stems of woody plants; do not pile against the trunk. Primary reference for the volcano warning. Does not publish bag sizes or a settlement percentage.
  2. Penn State Extension: Mulching Landscape Trees · Penn State Cooperative Extension. Confirms finely shredded mulches decompose faster and require more frequent replenishment. Does not quantify a year-one volume-loss figure; the 25 percent settlement constant in the calculator is a landscape trade rule-of-thumb, not a PSU value.
  3. International Society of Arboriculture: Proper Mulching · ISA consumer guide. Covers the 2-4 in. depth standard, mulch-volcano damage, and the 6 in. trunk-clearance rule. Industry-standard reference for proper mulching technique.
Note 05 · Field Manual

What the sheet count does not tell you

A 200-square-foot bed, worked out

Take a 200 square foot foundation bed mulched 3 inches deep. Volume is area times depth in feet: 200 times one-quarter of a foot is 50 cubic feet, or 1.85 cubic yards. In bags that is 25 of the standard 2 cubic foot bags. Here the money splits: bulk delivery of 1.85 yards runs about 56 to 111 dollars depending on the mulch, while 25 bags at roughly 4 dollars each is about 100 dollars. Bulk wins on price above two yards or so and wins bigger the larger the bed; bags win on small jobs where the delivery minimum and fee swamp the savings. Order depth is pre-settlement: shredded mulch loses about a quarter of its loose volume in the first year as it breaks down.

Depth, and the mulch volcano

Depth is where mulch goes from helping to killing. New beds want 3 inches; refreshing existing mulch wants 1.5 to 2 inches over what is left, not another full 3 on top. The failure mode university extensions call out the most is the mulch volcano: a cone of mulch piled against a tree trunk. Bark needs to breathe, and mulch packed against it traps moisture, rots the bark, and invites the pests and disease that kill the tree slowly over a few seasons. Keep a 3 to 6 inch gap around every trunk, and pull mulch back from foundation walls and wood siding for the same reason. The calculator fires a hard warning past 4 inches of depth, because that is the line where over-mulching starts doing damage instead of good.

Bulk versus bagged, and which mulch

Bagged mulch is convenient and portable, and it is the right call for a tree ring or a single small bed you can carry in a car. Past a couple of cubic yards, bulk delivery is dramatically cheaper per yard, and a yard of bulk is about 13 and a half of the 2 cubic foot bags. The trade-off is a wheelbarrow and an afternoon against stacking bags. On type, shredded hardwood is the workhorse: it knits together, holds a slope, and breaks down into the soil. Bark nuggets float and wash off in heavy rain, so they suit flat beds, not grades. Dyed mulch holds color longer but says nothing about what is underneath; the dye coats the surface of whatever wood got ground up. None of this changes the volume, but it changes what shows up on the truck.

Note 06 · Common Questions

Common questions

How much mulch do I need?
Multiply the bed area by the depth in feet. A 200 square foot bed at 3 inches is 50 cubic feet, or 1.85 cubic yards, which is 25 of the standard 2 cubic foot bags. New beds want 3 inches; refreshing wants 1.5 to 2 inches over what is left. The calculator returns both the bulk yardage and the bag count so you can price either.
How many bags of mulch are in a yard?
About 13 and a half of the standard 2 cubic foot bags make a cubic yard (27 cubic feet). Some premium and specialty lines ship 1.5 cubic foot bags, which take 18 to the yard. Past two yards, bulk delivery is cheaper than bags, and the gap widens with the size of the job.
How deep should mulch be?
Three inches for a new bed, 1.5 to 2 inches to refresh existing mulch, measured over what is already there. More than 4 inches total against trunks and stems causes rot. Keep a 3 to 6 inch gap around tree trunks, foundation walls, and wood siding; piling mulch against wood is how the mulch volcano kills the plant it was meant to protect.
Is it cheaper to buy mulch in bags or in bulk?
Bulk wins past about two cubic yards. A yard of bulk mulch costs far less than the 13 and a half bags it replaces, but bulk carries a delivery minimum and fee that make small jobs cheaper by the bag. For a tree ring or one small bed, buy bags; for a full property, order bulk by the yard.
PROJ MATERIALFOREMAN
SHT M-001 / 014
REV A · 2026-06-07
DRAWN MF