Mulch Calculator
Work out how much mulch a bed really needs with this mulch calculator. Pick the bed shape, type the size and the depth, and read the full order in one result. The tool shows cubic yards, the bag count for 2 and 3 cubic foot bags, the coverage of one yard at your depth, and the bag route and bulk route costs side by side. It suits garden beds, tree rings and play areas.
What the result numbers mean
The order number for bulk mulch. One cubic yard is 27 cubic feet, and it is the unit landscape yards sell by.
The same job counted in bags of your chosen size. The count rounds up, so the last corner of the bed never stays bare.
The ground one cubic yard covers at your depth. At 3 inches deep, one yard covers 108 square feet.
Depth drives the whole order. The same bed at 2 inches and at 4 inches takes half or double the mulch.
Add a price per bag and the tool prices the full bag count for this exact bed.
Add a price per cubic yard and the tool prices bulk. Compare both lines. Past a few yards, bulk usually wins big.
How much mulch do I need?
Multiply the bed length by the width by the depth in feet, then divide by 27. A bed 10 by 5 foot at 3 inches deep holds 0.46 cubic yards. That is 7 bags of 2 cubic feet.
How the math works
Choose a rectangle for beds and borders. Choose a circle for tree rings and round beds around a trunk or a post.
Type the length and the width in feet. A bent bed splits into sections. Run each section and add the yards together.
Match the depth to the purpose. A refresh takes 2 inches. A standard bed takes 3. A new bed that must block weeds takes 4.
Refresh 2 in, Beds 3 in, New 4 inThe tool multiplies length by width by depth for cubic feet, then divides by 27. Yards are the unit bulk sellers use.
Cubic feet / 27Divide the cubic feet by your bag size. One yard holds 13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet.
Cubic feet / Bag sizeRead both cost lines. Bags win on tiny jobs. Bulk wins as the yards climb, and past about 3 yards it often costs near half.
A garden bed, 10 by 5 foot at 3 inches deep
Here is the bed from the quick answer, on a breakdown slip, the way the tool builds it.
Read the slip top to bottom. The volume is the bare bed at depth. The yard line is the bulk order. The bag line is the shelf order. Add a price to both routes in the tool and this small bed shows bags ahead. A bed four times bigger flips the winner.
Shapes and depths, explained
This mulch calculator turns shape and depth into one order. The depth choice moves the number more than any other field, so pick it by the job the mulch must do. Tap a card to load it in the tool.
Garden beds, borders and vegetable rows. Measure the length and the width in feet. Long beds can run in sections when they bend.
Key measure: length and width in feetTap to load in the calculatorRings around trees and round beds. Measure straight across the middle for the diameter. Keep mulch a few inches away from the trunk itself.
Key measure: diameter across the middleTap to load in the calculatorA tired bed that still holds its shape needs a top up, not a rebuild. Two inches brings the color and cover back.
Key measure: depth 2 inTap to load in the calculatorThe working depth for most beds. Three inches holds moisture, cools the soil and slows weeds through the season.
Key measure: depth 3 inTap to load in the calculatorFresh ground and strong weed pressure want a deep layer. Four inches blocks light well while the plants fill in.
Key measure: depth 4 inTap to load in the calculatorOne yard is about 13.5 bags of 2 cubic feet. When a job passes 3 yards, the bag count passes 40 and bulk delivery usually takes the win.
Key measure: about 3 cubic yardsOrganic and synthetic mulch
Mulch splits into two families, organic and inorganic. The family decides what the bed gets over time, not just how it looks on day one.
Organic mulches
Bark, shredded hardwood, cedar chips and pine straw all rot down in time. The rot feeds the soil and holds moisture on the way through. Beds need a fresh top layer every year or two as the old layer thins.
Synthetic mulches
Rubber mulch and stone never rot. Gardeners call this family inorganic, or synthetic. They hold color for years and stay put in windy spots. They add nothing to the soil, and stone bakes roots in hot summer sun.
Pick by the bed
Living beds with shrubs and flowers suit organic mulch. Play areas, paths and dry slopes suit rubber or stone. Match the mulch to what lives in the bed.
Landscape fabric under mulch
Fabric under organic mulch causes more trouble than it saves. The mulch rots on top of the cloth and builds a soil layer where weeds root anyway. Plant roots tangle into the fabric, and old fabric turns bed cleanouts into a fight.
Fabric earns its place under stone, gravel and paths. Nothing needs to reach the soil there, and the cloth keeps stone from sinking into soft ground.
How to apply mulch the right way
Weed the bed first and water the soil well. Spread the mulch 2 to 4 inches deep and keep the layer even from edge to edge.
Pull mulch a few inches back from trunks and stems. A mulch volcano piled against bark traps moisture and invites rot, pests and disease. Leave the root flare of a tree in open air.
Edge the bed or add a border so the layer stays put. Top up thin spots each season. A fresh thin layer beats a full strip and rebuild.
Mulch numbers, in one place
| Depth | One cubic yard covers |
|---|---|
| 2 in | 162 sq ft |
| 3 in | 108 sq ft |
| 4 in | 81 sq ft |
| 6 in | 54 sq ft |
Common mistakes
One inch of the old layer often stays in the bed. Order for the full depth anyway and the bed mounds up and spills onto the path.
A refresh and a new bed need very different depths. Two inches tops up. Four inches builds. The purpose picks the number.
Past about 3 yards, bags cost near double and the trips pile up. Read the yard count here before you choose the route.
A part bag never sells. A count that stops short leaves one corner of the bed bare. The tool rounds up for you.
How to buy mulch for your beds
The result moment is the buying moment. Use the yards and the bag count from this mulch calculator at the shelf or on the phone with the yard. Two routes cover almost every job.
Option A: The bag route
- Bags keep colors apart. One bed can take black and the next can take natural.
- A car carries a small bed in one trip, with no delivery fee.
- Pick one brand and size for the whole job, so the color matches.
- Stack bags flat and dry. A torn wet bag makes a heavy mess.
Option B: Bulk by the yard
- Bulk runs near half the bag cost per yard at this size.
- Ask for the full price with delivery before you book.
- Pick the drop spot near the beds. Mulch moves by the barrow load.
- Cover the pile with a tarp when rain threatens. Dry mulch spreads fast.
For the soil under a new bed, the topsoil calculator gives yards, tons and bags in the same style. For a stone bed or a path instead of mulch, the gravel calculator weighs the job by type.
Questions, answered
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