TOOL_02 · Landscape mulch
Mulch calculator
Bags or bulk — depth-aware, bed-size presets, and the skid-steer scoop math nobody else shows you.
① Your beds
Bags (3 cu ft)
0bags
25 bags if buying 2 cu ft
Bulk delivery
0.0cu yd
4 skid-steer scoops (½ yd each)
Material Cost Estimator
Estimated Total for Mulch Bags
$76.50
17 units × $4.50 per 3 cu ft bag
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How to measure it on site
Mulch is sold by volume, so the only numbers that matter are bed area and the depth you actually want. Measure the bed once, decide the depth, and let the calculator turn those two figures into cubic yards and bags.
Measure the bed as simple shapes. Break curved beds into rectangles and triangles. A 4 ft × 20 ft strip is 80 sq ft; a triangular corner with a 6 ft base and 4 ft height is 12 sq ft. Add the pieces rather than guessing the total.
Decide whether this is a top-up or a new bed. An existing bed that is still covered needs about 1 inch to refresh the color. Bare soil that has never been mulched needs the full 3 inches. The difference is three times the material.
Check the depth you already have. Push a finger or a trowel into the bed in three or four spots. If you find 1 inch or more of sound mulch, top up rather than layer. If you find bare soil, measure for the full depth.
Subtract hardscape and plant crowns. Pavers, stepping stones, and tree wells do not take mulch. Subtract their footprint from the bed area, and keep the mulch 1 to 2 inches away from trunks and siding rather than piling it against them.
Common mistakes
Most mulch shortfalls and waste come from four habits that are easy to fix before you order.
- Treating a yearly top-up as a fresh bed. A 500 sq ft bed at 1 inch takes about 1.55 cubic yards. At 3 inches it takes 4.63. Spreading the full depth every spring builds a layer that sheds water and suffocates roots.
- Buying 2 cu ft bags when 3 cu ft bags are stocked. A 3 cu ft bag holds 50 percent more than a 2 cu ft bag, so the same volume needs a third fewer bags. On 125 cubic feet that is 42 bags instead of 63 — 21 fewer bags to lift and open.
- Forgetting that a cubic yard is 27 cubic feet. Bags are labeled in cubic feet and bulk is sold in cubic yards. Dividing cubic feet by 27 converts between them; skipping that step turns 4.63 yards into 125 yards on paper.
- Piling mulch against trunks and siding. Mulch held against bark keeps moisture on the trunk and invites rot; mulch against siding does the same to the wall. Pull it back 1 to 2 inches and keep the crown of the bed flat rather than cone-shaped.
- Ordering bulk before checking access. A cubic yard of mulch is a pile roughly 3 ft on each side and weighs several hundred pounds. If a truck cannot reach the bed, bags are the practical choice even though the unit volume is smaller.
Worked example
A 500 sq ft bed at 3 inches
This is a new bed with bare soil, so it needs the full depth. The bed is a simple rectangle and there is no hardscape to subtract.
- Area
- 500 sq ft
- Depth in feet
- 3 in ÷ 12 = 0.25 ft
- Volume
- 500 × 0.25 = 125 cu ft
- Cubic yards
- 125 ÷ 27 = 4.63, rounded up to 4.75 cu yd
- 2 cu ft bags
- 125 ÷ 2 = 62.5, rounded up to 63 bags
- 3 cu ft bags
- 125 ÷ 3 = 41.7, rounded up to 42 bags
Result: 4.75 cubic yards of bulk mulch, or 63 bags in 2 cu ft size, or 42 bags in 3 cu ft size. The volume is the same; only the packaging changes.
What this calculator doesn't cover
This calculator converts bed area and depth into volume. It does not cover these cases:
- Sloped beds — measure the horizontal footprint, then add material for the slope; the calculator assumes a flat surface.
- Soil amendment — tilling mulch into the soil is a different product and rate from a surface layer.
- Weight limits — bulk mulch is sold by volume but delivered by truck weight; check the supplier's load limit and access.
- Long-term buildup — three years of full-depth top-ups can raise the bed above the siding line, which the volume math cannot see.
Reviewed . Sources: Unit conversion: 1 cubic yard = 27 cubic feet (ASTM International); Bagged mulch volumes (2 cu ft and 3 cu ft packaging) (ASTM International). Full methodology.
How the math works
Volume: area × depth. One inch of depth over 1 sq ft is 1/12 cu ft. Total cubic feet ÷ 27 = cubic yards. Bags: divide by 2 or 3 depending on bag size, always rounding up.
Scoops: bulk deliveries are often priced per "scoop" — a skid-steer bucket load, roughly ½ cubic yard. The result card converts your yards to scoops so you can order like the locals do.
Pro move: order 5–10% extra bulk mulch. It settles within weeks, and a thin top-up next season is much easier than a full re-mulch.
Common questions
How deep should mulch be?
3 inches is the sweet spot for most beds: enough to suppress weeds and hold moisture without smothering roots. Use 2 inches for beds with shallow-rooted plants like azaleas and rhododendrons. Never pile mulch against tree trunks or stems — that invites rot and pests ('volcano mulching' kills trees slowly).
How much area does a bag of mulch cover?
A 3 cu ft bag covers about 12 sq ft at 3 inches deep, or 18 sq ft at 2 inches. A 2 cu ft bag covers about 8 sq ft at 3 inches. Bulk mulch is sold by the cubic yard (27 cu ft) — one yard covers about 108 sq ft at 3 inches deep.
Is bulk mulch cheaper than bags?
Almost always, and the reason is packaging. One cubic yard is 27 cubic feet, so a single yard is 9 bags of 3 cu ft — or about 14 bags of 2 cu ft. At 3 cubic yards you are looking at 27 bags to load, unload, and spread by hand, which is where bulk starts winning on handling as much as on material. The calculator returns the cubic-yard figure and both bag counts from the same area, so you can put the pallet and the truckload side by side before you commit.
How many bags of mulch do I need for 200 square feet?
At 3 inches deep, 200 sq ft needs about 50 cubic feet of mulch — that's 17 bags of 3 cu ft, 25 bags of 2 cu ft, or roughly 2 cubic yards bulk.
Estimates are for planning purposes. Actual coverage varies by mulch type, moisture, and how uneven your beds are.