About Mulch & Topsoil Calculator (Bags vs Bulk)
The mulch and topsoil calculator answers "how much mulch do I need" for beds and borders and "how much topsoil" for new or patched lawns. Enter up to 20 beds as length × width — or a single total area directly — plus the spread depth, and it returns the volume in cubic feet and cubic yards, the number of whole 2 or 3 ft³ bags, and the load weight from representative material densities so you can plan a pickup run or a bulk delivery.
Densities are stated as planning ranges, not product specs: hardwood mulch typically runs 400-800 lb/yd³ depending on moisture and species (600 midpoint used here), screened topsoil 2,000-2,400 lb/yd³ (2,200), and finished compost 1,000-1,600 lb/yd³ (1,300). Enter an optional bag price and bulk price and the tool shows both purchase totals side by side. Gravel, crushed stone, and stone mulch are deliberately out of scope — mineral materials live in the gravel & aggregate calculator, which handles compaction and tonnage properly.
How It Works
- Pick the entry mode: add each bed as length × width in feet (up to 20 beds), or switch to the direct entry and type the total square footage for irregular layouts you have already measured.
- Enter the spread depth in inches. Mulch is normally refreshed at 2-3 in; topsoil depends on the job — about 4-6 in for a new lawn, 1-2 in for patching or topdressing an existing one.
- Choose the material — hardwood mulch, screened topsoil, or compost — and the bag size your store sells (2 ft³ is the standard mulch bag, 3 ft³ the large one).
- The calculator computes ft³ = area × depth/12 and yd³ = ft³/27, rounds bags up to whole units, and multiplies the cubic yards by the representative density for the load weight in pounds and US short tons.
- Optionally enter a $/bag and a $/yd³ bulk price to see both purchase totals side by side — bagged material usually wins for small jobs, bulk delivery for anything beyond a couple of yards.
Worked Example
Take the 500 ft² mulch row from the table below — a typical season's worth of beds getting a 3 in top-up of hardwood mulch. The volume is 500 × 3/12 = 125 ft³ = 125/27 = 4.63 yd³. In standard 2 ft³ bags that is 125/2 = 62.5, so 63 bags; in 3 ft³ bags 125/3 = 41.7, so 42 bags. At the 600 lb/yd³ representative mulch density the load weighs 4.63 × 600 = 2,778 lb (1.39 tons) — the same volume of screened topsoil at 2,200 lb/yd³ would be 10,185 lb, about 5.09 tons, far beyond any pickup truck. The buy decision comes down to price: with mulch at $4 per 2 ft³ bag versus $45/yd³ bulk, the bagged total is 63 × $4 = $252 against 4.63 × $45 = $208.33 delivered loose — at this volume bulk already wins, and the gap widens with every additional bed.
How many bags or yards of mulch do I need?
Bed and lawn sizes people actually price out, entered as a direct total area in the tool. Bags are the standard 2 ft³ size, and the load weight uses each row's named material at the tool's representative density — hardwood mulch 600 lb/yd³, screened topsoil 2,200, compost 1,300.
| Project | Volume (yd³) | 2 ft³ bags | Load weight (tons) |
|---|---|---|---|
| 100 ft² flower bed, 3 in of mulch | 0.93 | 13 | 0.28 |
| 200 ft² of beds, 3 in of mulch | 1.85 | 25 | 0.56 |
| 500 ft² of beds, 3 in of mulch | 4.63 | 63 | 1.39 |
| 1,000 ft² of beds, 2 in mulch refresh | 6.17 | 84 | 1.85 |
| 1,000 ft² new lawn, 4 in of topsoil | 12.35 | 167 | 13.58 |
| 500 ft² vegetable garden, 2 in of compost | 3.09 | 42 | 2.01 |
Formulas
- Spread volume
V_ft3 = A × d / 12 ; V_yd3 = V_ft3 / 27- Whole bags
N_bags = ceil( V_ft3 / bag size )- Load weight
W_lb = V_yd3 × ρ ; tons = W_lb / 2000- Bagged vs bulk cost
C_bags = N_bags × $/bag ; C_bulk = V_yd3 × $/yd³
Standards & References
- Representative landscaping practice — loose bulk density ranges: hardwood mulch 400-800 lb/yd³, screened topsoil 2,000-2,400 lb/yd³, finished compost 1,000-1,600 lb/yd³
- US customary bagged sizes: 2 ft³ and 3 ft³ (27 ft³ per cubic yard)
Frequently Asked Questions
How many bags of mulch are in a cubic yard?
A cubic yard is 27 ft³, so it equals 13.5 standard 2 ft³ bags or 9 of the large 3 ft³ bags. That ratio is the quickest bags-vs-bulk sanity check: a job needing more than a yard or two is usually cheaper delivered loose, while under half a yard the bags win on convenience and no delivery fee.
How deep should mulch be?
A 2-3 in settled layer is the standard recommendation: enough to suppress weeds and hold moisture without smothering roots. An annual refresh over old mulch often needs only 1-2 in. Keep mulch pulled a few inches back from trunks and stems — piling it against bark ("volcano mulching") traps moisture and invites rot and pests.
How much topsoil do I need for a new lawn?
Seeding or sodding a new lawn typically wants 4-6 in of quality topsoil, while patching bare spots or topdressing an existing lawn needs only 1-2 in (about 1/4-1/2 in per topdressing pass is common). At 4 in, every 1,000 ft² takes roughly 12.3 yd³ — new-lawn topsoil is almost always a bulk delivery, not a bag purchase.
How much does a yard of mulch or topsoil weigh?
Representative loose weights per cubic yard: hardwood mulch 400-800 lb depending on moisture and species (600 is a good planning midpoint), screened topsoil 2,000-2,400 lb, and finished compost 1,000-1,600 lb. Weight is why delivery planning matters: a half-ton pickup can carry about one yard of dry mulch, but only a fraction of a yard of topsoil — a ton of soil is well under half a yard.
Is bulk mulch cheaper than bags?
Per cubic yard, bulk is usually much cheaper — a yard of bagged mulch at $4 per 2 ft³ bag costs 13.5 × $4 = $54 in material alone, where bulk often runs $30-50/yd³. Bags win on small quantities, storability, and no delivery fee. Enter both prices in the calculator and it shows the two totals side by side for your exact volume.
How much mulch do I need for 500 square feet?
At the standard 3 in depth, 500 ft² takes 500 × 3/12 = 125 ft³ = 4.63 yd³ — 63 standard 2 ft³ bags or 42 of the large 3 ft³ bags. That is the 500 ft² row in the table above and the volume where bulk delivery usually starts beating bagged prices. A lighter 2 in refresh over existing mulch drops the order to about 3.09 yd³, or 42 of the 2 ft³ bags.
How much area does a yard of mulch cover?
A cubic yard is 27 ft³, so its coverage is 27 ÷ (depth ÷ 12): about 108 ft² at 3 in deep, 162 ft² at 2 in, and 324 ft² at a 1 in topdressing. Divide your bed area by the coverage for a quick yard estimate, or enter the exact area and depth in the calculator to get the volume, bag count, and load weight together.
How many bags of mulch for a 100 square foot bed?
A 100 ft² bed at 3 in deep needs 25 ft³ of mulch — 13 standard 2 ft³ bags (12.5 rounded up to whole bags), weighing roughly 560 lb at the 600 lb/yd³ representative density. That is comfortably a single car-trunk-and-weekend job, which is exactly the quantity range where bagged mulch beats arranging a bulk delivery.
Does this calculator cover gravel or stone mulch?
No — gravel, crushed stone, river rock, and other mineral mulches are handled by the gravel & aggregate calculator, which carries the right densities (roughly 2,400-2,900 lb/yd³, several times heavier than bark mulch) plus compaction and truckload logic. This tool covers organic materials: wood mulch, screened topsoil, and compost.