Mulch Calculator

How much mulch do you need? Multiply bed area by depth in feet, then divide by 27 for cubic yards. A 200-square-foot bed at 3 inches deep needs 50 cubic feet, about 1.85 cubic yards or 25 bags of 2 cubic feet. This mulch calculator runs that math instantly from length, width, and depth, and adds a 10% buffer so you only make one trip.

The core idea is simple: mulch is sold by volume, and volume is just area multiplied by depth. A 200-square-foot bed spread 3 inches deep needs the same 50 cubic feet of mulch whether it is dyed hardwood, cedar, or pine bark. What changes between materials is the weight and the price, not the cubic yards. That is why this tool focuses on getting the volume right first, then converts it into bags, yards, and an approximate weight so you can plan delivery or hauling.

This tool is for the landscaping bed part of a yard project. For hardscape and structure, reach for a sibling: pour a slab, footing, or path with the Concrete Calculator, coat a fence or shed with the Paint Calculator, and if the project touches the roof, size shingles with the Roofing Calculator after finding your slope with the Roof Pitch Calculator.

A worked example with real numbers

Say you have a front garden bed that measures 20 feet long by 10 feet wide, and you want a 3-inch layer of mulch. Here is the math step by step:

• Area: 20 ft × 10 ft = 200 square feet.
• Depth in feet: 3 inches ÷ 12 = 0.25 feet.
• Cubic feet: 200 × 0.25 = 50 cubic feet.
• Cubic yards: 50 ÷ 27 = 1.85 cubic yards.
• Bags (2 cu ft each): 50 ÷ 2 = 25 bags.

So that one bed needs roughly 1.85 cubic yards of bulk mulch, or 25 bags. Add the recommended 10% extra and you would order about 2 cubic yards or 28 bags. Those three extra bags are cheap insurance against coming up short on the last few square feet.

How to figure mulch, step by step

The same five steps work for any bed. Here they are for the 20 ft × 10 ft bed at 3 inches deep:

The formula

Every result on this page comes from one formula, applied in plain U.S. units:

Breaking it down: depth in inches ÷ 12 converts your depth to feet, multiplying by area gives cubic feet, and dividing by 27 (the number of cubic feet in a cubic yard) gives cubic yards. To get bags instead, divide the cubic feet by the bag size: cubic feet ÷ 2 for the common 2-cubic-foot bag.

How to measure and use this calculator

You only need a tape measure and a minute. Work through the fields in order:

1. Measure the bed: for a rectangle, measure length and width in feet. For an irregular bed, break it into rectangles, measure each, and add the square footage, then switch the calculator to "Total sq ft" and enter the sum.
2. Pick a depth: 2 to 3 inches suits most beds (extension services advise against piling organic mulch much deeper in beds); 3 to 4 inches is suggested for rings around trees. The quick buttons set 2, 3, or 4 inches instantly.
3. Choose how you will buy: the calculator shows both cubic yards (for bulk) and bag count. Set the bag size to match what your store sells; 2 cu ft is the default.
4. Read the results: the big number at the top is cubic yards. Below it you will find cubic feet, bag count, approximate weight, and a coverage-by-depth table.
5. Add the buffer: use the "with 10% extra" figures when you place your order. It is the line item that keeps you from a second trip.

Who this calculator is for

If you are putting down mulch this season, this tool saves you guesswork. It is built for:

• Homeowners refreshing flower beds, shrub borders, or the strip along the driveway each spring.
• New gardeners who want a clear, no-jargon answer to "how many bags do I need?"
• DIY landscapers deciding whether a bulk delivery beats hauling dozens of bags.
• Budget planners who want a cubic-yard or bag count before pricing it out at the store.
• Anyone with an oddly shaped yard who needs to add up several beds into one order.

Key terms explained

• Cubic foot: a one-by-one-by-one-foot box of material. Bagged mulch is measured this way; a common bag holds 2 cubic feet.
• Cubic yard: 27 cubic feet, the unit bulk mulch is sold and delivered in. One yard equals about 13.5 bags of 2 cubic feet.
• Depth (or coverage depth): how thick the mulch layer is, in inches. Doubling the depth doubles the volume you need.
• Coverage: the square footage one yard or bag covers at a given depth; a cubic yard covers about 108 sq ft at 3 inches.
• Waste factor: the extra you add (about 10%) for settling, spillage, and irregular beds.
• Bulk vs. bagged: bulk is loose material sold by the yard; bagged is pre-packaged and easier for small jobs.

How many bags is a yard of mulch? (cubic yards to bags)

A cubic yard is 27 cubic feet, so the bag count depends only on bag size. This table converts bulk yards into bags at the three common sizes and shows how many square feet each amount covers at 2, 3, and 4 inches deep.

Round bag counts up when you buy: you cannot purchase half a bag. One 2-cubic-foot bag itself covers about 12 sq ft at 2 inches, 8 sq ft at 3 inches, or 6 sq ft at 4 inches.

Three common scenarios

Here is how the numbers play out for jobs of different sizes, all at a 3-inch depth with 2-cu-ft bags:

• Small bed (100 sq ft): 25 cubic feet, about 0.93 cubic yards or 13 bags. Bagging it is fine here.
• Medium yard (400 sq ft): 100 cubic feet, about 3.7 cubic yards or 50 bags. At 50 bags, it is worth pricing a bulk delivery against the bags.
• Large landscape (1,000 sq ft): 250 cubic feet, about 9.3 cubic yards or 125 bags. Hauling 125 bags is a lot of lifting and trunk space, so bulk is the practical choice.

Notice the pattern: the bag count climbs quickly (13.5 bags of 2 cu ft per cubic yard), so on larger jobs it pays to price a bulk delivery against the bags.

Mulch needed by bed size and depth

Find your bed's square footage down the left, read across to your depth. Each cell shows cubic yards / 2-cu-ft bags (bags rounded up). Add 10% before ordering.

The 3-inch column is the everyday default. Reading it confirms the rule of thumb: at 3 inches, one cubic yard covers about 108 sq ft, so cubic yards needed ≈ bed area ÷ 108.

What changes the result the most

Adjust the inputs and you will see a few factors dominate the total:

• Area: the biggest driver. Doubling the bed size doubles the mulch needed.
• Depth: a hidden multiplier. Going from 2 inches to 4 inches doubles your order even though the bed is the same size.
• Bag size: only affects the bag count, not the volume. Switching from 2-cu-ft to 3-cu-ft bags cuts the number of bags by a third.
• Bed shape: irregular and curved beds waste more, which is exactly what the 10% buffer is for.
• Material type: changes weight and price, not cubic yards: useful for hauling, irrelevant for how much to order.

Tips for ordering and spreading mulch

• Always order about 10% extra. Settling and irregular beds eat into coverage, and a leftover bag is cheaper than a second trip.
• Keep mulch off trunks and stems. A "mulch volcano" piled against a tree traps moisture against the bark and invites rot and rodents; leave 2 to 3 inches of clearance.
• Don't pile it too deep. University of Maryland Extension advises that organic mulch should not exceed 3 inches; deeper layers can starve roots of oxygen and hold too much moisture.
• Refresh, don't replace. Organic mulch breaks down over time; top up to bring the layer back to 2 to 3 inches rather than stripping and starting over.
• Check your vehicle's capacity. A cubic yard of wood chips weighs roughly 243 to 473 pounds by EPA's factors, so check the payload on your vehicle's tire and loading placard before hauling several yards.

Limitations and assumptions

This is a planning estimate, not a guarantee. Keep these assumptions in mind:

• It assumes a level, evenly spread layer at the depth you enter; slopes and mounding change real coverage.
• The weight range uses EPA factors for wood chips (243 lb per cubic yard dry, 473 lb green). Bark, rubber, and stone "mulch" weigh differently, and wet material is heavier.
• It does not account for edging, paths, plants, or obstacles inside the bed: subtract those areas if they are large.
• Supplier measurements vary slightly: a "yard" delivered loose can differ from the calculated volume after it settles.
• The 10% buffer is a guideline; very irregular or steeply sloped beds may need a bit more.

Bagged vs. bulk: estimating the cost

Once you know the cubic yards, turning that into a dollar figure is straightforward, and it is usually where the bagged-vs-bulk decision is settled. Bagged mulch is priced per bag, so multiply the bag count by the per-bag price. Bulk mulch is priced per cubic yard, often plus a delivery fee. To compare like for like, multiply the bag price by the bags in a yard (13.5 for 2-cubic-foot bags) and set that against the bulk price per yard. On a small job a flat delivery fee can outweigh any bulk savings; on a large one, hauling dozens of bags becomes the bigger cost. Remember to price the with-10%-extra figure, not the bare estimate. If you are quoting several materials for one project, the Gravel Calculator and Topsoil Calculator report tons too, which many suppliers also price by.

Mulch depth by use: a quick guide

Depth is the input people get wrong most often, and it changes both the result and the health of your plants. Match the depth to the job:

• Annual flower beds and vegetable gardens: 1 to 2 inches. Thin layers let seedlings emerge and soil warm in spring while still cutting weeds.
• Perennial beds and shrub borders: 2 to 3 inches, the all-purpose default for moisture retention and weed suppression.
• Around trees: Mississippi State University Extension suggests 3 to 4 inches in a ring reaching 3 to 6 feet from the trunk, pulled 2 to 3 inches back from the bark. Wide, flat rings beat deep mounds.
• Pathways (wood chips): 3 to 4 inches for a stable surface that resists tracking.
• Under swings and play equipment: this is impact surfacing, not a garden bed. The CPSC playground handbook calls for at least 9 inches of compressed wood mulch or wood chips, so install about 12 inches.
• Slopes: a slightly heavier coarse mulch resists washout; this is one case where adding a bit more than the 10% buffer pays off.

Whatever depth you pick, set it before you measure: because depth is a multiplier, changing your mind from 2 to 4 inches doubles the order, as the Cubic Yard Calculator will also show for any loose material.

Related materials and calculators

The same area-times-depth math powers most landscaping estimates. If you are working with a different material, a sister tool fits better:

• For loose stone or rock, use the Gravel Calculator, which reports tons as well as yards.
• For dirt, soil, or raised beds, use the Topsoil Calculator.
• To convert any dimensions into yards for a generic material, use the Cubic Yard Calculator.
• To find the square footage of a bed or room first, use the Square Footage Calculator.
• For slabs and footings, use the Concrete Calculator; for walls and ceilings, the Paint Calculator or Tile Calculator.

Sources

• University of Maryland Extension: Excess Mulch Problems (organic mulch no deeper than 3 inches; pull it about 3 inches back from the bark).
• Mississippi State University Extension: How to Mulch (3 to 4 inches around trees, kept 2 to 3 inches from the trunk).
• U.S. Environmental Protection Agency: Volume-to-Weight Conversion Factors, April 2016 (PDF) (wood chips: 243 lb per cubic yard dry, 473 lb green).
• U.S. Consumer Product Safety Commission: Public Playground Safety Handbook (PDF), Table 2 (minimum compressed loose-fill surfacing depths).
• National Institute of Standards and Technology: NIST Handbook 44 (2026), Appendix C (PDF) (27 cubic feet = 1 cubic yard).