Bags or bulk — what should I actually order?
Mulch isn't just square feet × depth. The real ordering decision is bags vs bulk, and it flips around 3 cubic yards — but supplier minimums and delivery fees move the line.
- Small touch-up — usually bags. A single bed or a shrub border under 1 yd³ goes home in the car. No delivery fee erases the savings.
- Weekend project, several beds — compare. At 1-3 yd³ run the bag count against bulk + delivery. Most Chicago-suburb yards charge for the short-load anyway, so bagged often still wins.
- 3+ cubic yards — bulk usually wins, with a caveat. Bulk is cheaper per yard, but only if the truck can reach a drop point (driveway, curb, level grass). A 3 yd³ pile dumped two yards from the bed turns into wheelbarrow trips that erase the savings.
- Always check the supplier minimum first.Some yards won't deliver under 3 yd³; others charge a $50-$120 short-load fee under their threshold. That fee is the number to beat, not the bag price.
One concrete example: on a Chicago flip in 2022 the four front beds penciled to 3 yd³ practical, which usually means bulk. The alley wouldn't take a delivery truck, so we went bagged — 41 of the 2 cu ft bags or 27 of the 3 cu ft. Access overrode the math. If you're unsure how the bag count and yard math line up, the cubic-yard coverage table shows what a yard actually covers and how the 14-vs-9 bag count shakes out.
14 × 2 ft³ bags
≈ 1 cubic yard
28 ft³ (27 ÷ 2 = 13.5, rounds up to 14)
9 × 3 ft³ bags
= 1 cubic yard
27 ft³ exactly (27 ÷ 3 = 9 even)
1 yd³ bulk pile
= 1 cubic yard
27 ft³ delivered loose
New bed vs refresh — different depth, different math
Two beds with the same square footage can need very different amounts of mulch. The settling toggle in the calculator is built for this.
- New bed.Bare soil, no previous mulch — usually 2-3″ for ornamental beds, 1.5″ for vegetable beds. Leave the first-year settling cushion ON. Fresh wood-chip mulch loses about a quarter of its volume in the first six weeks; the cushion is what gets you to next year's refresh without a midsummer top-up.
- Refresh.Bed has settled mulch from last year — usually 1-2″ of new mulch is enough to bring the surface back to full depth. Toggle the settling cushion OFF; the new layer sits on top of stable material that's already done its compressing.
- Don't stack mulch year after year.Refresh mulch displaces last year's decomposing layer, not piles on top of it. If the bed surface is climbing year-over-year, that isn't deeper mulch — it's buried root flare and suffocated crowns. Pull some back before adding more, and check that the soil grade still sheds water away from the house.
Per-bed math at 3″ ornamental depth lives in the garden-bed mulch guide — same formula, walked through for a typical foundation bed.
Tree rings — the one place where more mulch hurts
Tree-ring mode in the calculator surfaces a warning for a reason. For every other bed, slightly more mulch is at worst wasteful. Around a tree, mulch piled against the trunk kills it. The shape matters as much as the depth.
Correct — flat ring
Trunk flare visible · ~3″ deep
Mulch pulled ~3″ back from the bark
Don't — volcano
Mulch piled against bark
Rots cambium · invites pests · kills the tree
- 3-3-3 rule (young trees). About 3 inches deep, 3 feet wide, and 3 inches pulled back from the trunk. Easy to remember, hard to mess up.
- Larger or established trees. Extend the flat ring outward toward the canopy edge (the dripline) when you have the space — same flat shape, same trunk gap, just a wider ring.
- Root flare should be visible.If you can't see where the trunk widens into the roots, the mulch is too high.
- Tree mode in the calculator uses the ring area at the canopy edge, not the depth at the trunk. The number it surfaces is for the flat ring, never for the cone.
Where mulch orders go wrong
The math itself is simple. Most bad mulch orders come from process mistakes upstream of the formula:
- Measuring bed area too loosely.Pacing it off and calling it 200 sq ft when it's 280 is how you end up two yards short on Saturday morning. Use a tape on the long edge and short edge of each bed; add the squares.
- Forgetting depth.Plugging in length and width without thinking about whether this is a new bed (3″) or a refresh (1-2″) gives a number that's right for someone else's project.
- Mixing 2 cu ft and 3 cu ft bag math.A pallet sticker says “3 cu ft”; the next aisle says “2 cu ft”; price-per-bag tricks you into thinking you're comparing the same thing. Always compare price per cubic foot, or use the calculator's bag-size selector. The square-yard vs cubic-yard guide covers the unit-confusion trap that quietly costs people 27× the mulch.
- Ordering exact geometry with no settling cushion. Bare math gives you the depth at spread time. Six weeks later the surface is a quarter shorter. The cushion isn't padding — it's the difference between “still looks mulched in August” and “needs a top-up by July.”
- Piling mulch against trunks. Volcano mulching is the single most common way to kill a young tree. See above.
- Assuming bulk is always cheaper. Bulk is cheaper per yard. After the delivery fee + short-load surcharge + the wheelbarrow trips, a 2 yd³ order can pencil out the same as bagged or worse.
- Ignoring supplier minimums and delivery windows. Many landscape yards won't deliver under 3 yd³ at all, and spring delivery windows can stretch to 7-10 days when everyone else is mulching too. Call the supplier before you build a weekend around a delivery.
Worked example — one big bed, 240 sq ft × 3″
Four landscape beds across the front of a house combined to roughly 240 sq ft on a Chicago flip in 2022. The math: 240 × (3/12) / 27 = 2.22 yd³ exact. With the 25% first-year settling cushion, that rounds to 3.0 yd³ practical — right at the typical supplier bulk minimum. In bags: 41 of the 2 cu ft, or 27 of the 3 cu ft.
The number that beats the math is access. The alley wouldn't take a delivery truck, so even though 3 yd³ would normally swing bulk, the order went bagged. Default bulk above 2-3 yd³ if the truck can reach the drop; default bags if it can't — and check the supplier's minimum on the phone before you commit to a number.
Methodology
Every number on this page traces to one of three layers — site arithmetic for the volume math, manufacturer-conventional bag sizes (2 cu ft and 3 cu ft) for bag counts, and arboriculture + extension-service guidance for depth recommendations and tree protection. The per-calculator sourcing tier in methodology spells out which sources back which kinds of claims.
Show the formulas
- Volume:
(L ft × W ft) × (D″ / 12) / 27= cubic yards. - Practical order, with settling: exact × (1 + waste%/100) × 1.25, rounded UP to the next 0.25 yd³.
- Practical order, no settling: exact × (1 + waste%/100), rounded UP. Use for refreshing already-settled beds.
- Bag count, 2 cu ft:
ceil(practical × 13.5)— 13.5 bags / yd³. - Bag count, 3 cu ft:
ceil(practical × 9)— 9 bags / yd³.
Frequently asked
How much mulch do I need for 240 sq ft of beds at 3″ deep?
About 3 cubic yards. 2.22 yd³ exact, rounded to 3 with the cushion that absorbs settling. The math: 240 × (3/12) = 60 cu ft. Divided by 27 gives 2.22 yd³ exact. With the 5% waste cushion plus the 25% first-year settling adjustment, the practical order is 3.0 yd³. In bags: 41 of the 2 cu ft bags, or 27 of the 3 cu ft bags. Bulk vs bagged at this size: 3 yd³ is right at the typical supplier minimum — bagged is usually the cleaner call unless you're already paying for delivery.
How thick should mulch be in a landscape bed?
2-4 inches for ornamental beds and around landscape trees. 1.5 inches for vegetable gardens. Why not deeper: Above 4″, mulch traps too much moisture and starves roots. Why not thinner: Below 2″, it doesn't suppress weeds. Why the veggie garden is different: Vegetable beds want a shallower layer so soil temperature stays more responsive — warming faster in spring, cooling slower into early summer. The calculator's defaults: 3″ for ornamental beds and tree rings; 1.5″ for vegetable gardens.
Why does the calculator add 25% on top of the waste cushion?
Fresh wood-chip mulch loses 25-30% of its bulk in the first six weeks as it compresses and the surface settles. A 3″ application becomes 2-2.25″ by mid-summer. What the cushion buys you: Coverage that holds through the season, so you don't need a midsummer top-up. By next year's refresh, you're starting from a stable base. When to toggle the cushion OFF: You're refreshing an already-settled existing bed where last year's mulch has already compacted — the new layer goes on top of stable material, no settling adjustment needed.
How many bags of mulch are in a yard?
14 bags at 2 cu ft per bag, or 9 bags at 3 cu ft per bag. The math: One cubic yard is 27 cubic feet. Divide by bag size: 27 ÷ 2 = 13.5, rounded up to 14. 27 ÷ 3 = 9 even. Which bag size to pick: 2 cu ft bags are easier to lift and stack in a Subaru; 3 cu ft bags are the better deal per yard if you've got truck access and a wheelbarrow. The calculator computes the exact ceiling for whichever bag size you select.
Should I volcano-mulch my trees?
No. Piling mulch in a cone against the trunk traps moisture, rots bark, and invites pest damage. Most calculators won't tell you that. The correct shape: A flat ring, not a cone. 2-4″ deep at the canopy edge, with the mulch pulled back from the trunk so the root flare is visible. The easy-to-remember version: The 3-3-3 rule — 3 inches deep, 3 inches pulled back from the trunk, in a 3-foot-wide ring. Where this comes from: The arboriculture standard for tree mulching and Penn State Extension's mulching guidance. The calculator's “Tree ring” mode renders a warning when selected.
Should I use bagged or bulk mulch?
Above 3 cubic yards, bulk delivery is almost always cheaper per yard. Below 3 yd³, bagged usually wins. The physical trade-off: Bulk saves you a Saturday's worth of bag-opening, but adds a Saturday's worth of wheelbarrow runs. Pick the labor you'd rather do. Buy bulk when: Project is over 3 yd³, OR you have a truck and a wheelbarrow and the supplier delivers cheap. Use bagged when: Project is under 3 yd³, OR access is too tight for a delivery truck. The awkward middle: 1-3 yd³ — bulk is cheaper per yard, but most Chicago-suburb suppliers won't deliver under 3 yd³ without a short-load fee. The calculator flags this with a “below bulk minimum” status.
What I'd do next
- Per-bed math at 3″ depth
Most beds want 3″. The 25% first-year settling cushion is non-optional.
- What a cubic yard actually covers (bag math + coverage)
Bag count, cubic-yard coverage table, and the settling cushion — the bag-vs-bulk price flips at ~3 yd³.
- Square yard vs cubic yard
The unit confusion that costs people 27× the right amount of mulch. Worth 60 seconds before ordering.
By James Wu. Volume math is site arithmetic, formulas shown above. Mulch depth recommendations + tree protection from Penn State Extension — Mulching Landscape Trees (the 2-4″ depth range, the 3-3-3 rule, the trunk-distance guidance). Arboriculture standard via ANSI A300 (Tree Care Industry Association) for the formal 2-4″ depth specification + the volcano-mulching prohibition. Tree-protection cross-check from Iowa State Extension — Mulch Depth Around Trees and Shrubs. Settling adjustment (~25% bulk volume loss in first 6 weeks) tracks Penn State Extension on landscape-tree mulching. Engine logic in lib/sitework/mulch.ts. Not arboriculture advice — for tree-care decisions specific to your trees, work with an ISA-certified arborist. Full methodology.