Mulch Calculator

How to calculate how much mulch you need

Mulch is sold by volume, so you need the bed area and the depth. Multiply them and convert to cubic yards for bulk, or cubic feet for bags:

Cubic yards = area (ft²) × depth (in) ÷ 324

The 324 is 12 inches per foot × 27 cubic feet per cubic yard. For bags, use cubic feet instead: area × depth (in) ÷ 12, then divide by the bag size printed on the bag.

1. Measure each bed. Rectangles are length × width. Use the circle option for tree rings. Split curved beds into rough rectangles and add them.
2. Subtract nothing for plants. Shrubs take up little volume at ground level, and the small surplus covers settling.
3. Pick a depth. Aim for a finished layer of 2–3 in (Clemson Extension). For a new bed, use 3 in. When topping up, enter only the difference between that and the depth still there.
4. Add about 10% for uneven ground and settling, then round to the nearest ½ yard you can order, or up to the next whole bag.

How much mulch for common bed sizes?

Most people search for their own bed: “mulch for 200 sq ft”, “how many bags for a 10×10”. This table answers the common sizes at 2 in and 3 in deep. Bag counts are exact, before any extra.

At 4 in deep every figure is one third larger than at 3 in. For metric beds, each centimetre of depth needs 10 litres of mulch per square metre, so a 7.5 cm layer is 75 L per m². Twenty square metres at 7.5 cm is 1.5 m³; a 2 ft³ bag holds about 56.6 L, so that is 27 bags.

At this size bulk is usually less work: 50 bags means 50 bags to lift, cut and dispose of, while 4 yd³ is a single delivery. Enter both prices in the calculator before deciding.

How far does a yard of mulch go?

One cubic yard covers 108 ft² at 3 in deep. Depth is the whole story: halving the depth doubles the coverage.

This also answers “how much will 25 bags of mulch cover”. Twenty-five 2 ft³ bags hold 50 ft³, enough for 300 ft² at 2 in or 200 ft² at 3 in.

How deep should mulch be?

For most beds, 2–3 in. Clemson Extension recommends keeping a 2–3 in layer of organic mulch over the roots of trees, shrubs and plant beds.

• Topping up existing mulch: only the difference needed to bring the layer back to 2–3 in (see the top-up steps below).
• New flower and shrub beds: 3 in, the top of Clemson’s 2–3 in range.
• Around trees: 2–3 in, spread out toward the outermost branches where possible, with at least a hand’s width of bare ground left around the trunk (Clemson Extension).
• Paths: our sources give no depth for mulch paths, so ask your supplier what depth they recommend for their chips. Playground surfacing has its own safety guidance, so follow the equipment maker’s instructions rather than a garden depth.
• Pine straw instead of wood mulch: it is sold by the bale, not the yard; use the pine straw calculator to count bales for the same beds.

Bags or bulk mulch: which should you buy?

Bags make sense for small jobs. Bulk makes sense once you need more than a couple of yards. The conversion that settles it:

• 1 yd³ = 27 ft³ = 13.5 bags of 2 ft³, 9 bags of 3 ft³ or 18 bags of 1.5 ft³.
• Multiply your bag price by 13.5 and compare it with the bulk price per yard plus delivery.
• Bulk mulch arrives as a loose pile, so you also need a wheelbarrow, a tarp to protect the driveway and time to spread it.

Prices change by region and season, so we do not quote averages. Enter your own bag or yard price in the calculator to see the total. Wood mulch is light: our calculator assumes about 0.4 tons (800 lb) per cubic yard, but wet mulch weighs more, so ask the supplier if you are hauling it yourself.

How much mulch per square foot and per 100 sq ft?

Each square foot of bed needs depth (in) ÷ 12 cubic feet of mulch: 0.167 ft³ at 2 in, 0.25 ft³ at 3 in and 0.333 ft³ at 4 in. Working in blocks of 100 ft² is easier, because most beds can be counted that way by eye.

Multiply the row by the number of hundreds you have. A 300 ft² bed at 3 in is three times 25 ft³, or 75 ft³ (2.78 yd³, 38 bags of 2 ft³). At 2 in the same bed takes 1.85 yd³, or 25 bags. Bag counts per 100 ft² are rounded up, so for big areas compute the total cubic feet first and divide once; multiplying rounded bag counts overstates the order.

Mulch for tree rings and the 3-3-3 rule

Tree rings are circles, so the area is π × radius². The ring grows fast with diameter: doubling the width from 4 ft to 8 ft quadruples the mulch.

The “3-3-3 rule” that shows up in search is a memory aid for tree mulch: a layer about 3 in deep, kept about 3 in away from the trunk, spread in a ring about 3 ft out from the trunk. It is not an extension standard: Clemson Extension recommends a 2–3 in layer with mulch kept at least a hand’s width from the trunk, so leave at least a hand’s width rather than exactly 3 in. A 3 ft radius is a 6 ft diameter ring, so one tree takes about 7.07 ft³, or 4 bags of 2 ft³. The trunk gap removes so little area that it does not change the bag count. Treat the rule as a starting point; larger trees benefit from wider rings, and your local extension office can advise for specific species.

For a row of trees, add the volumes before buying. Five trees with 6 ft rings at 3 in need 35.34 ft³ together, or 1.31 yd³. Counted one tree at a time that is 5 × 4 = 20 bags; counted as one total it is 18 bags, because the part-bag rounded up at each tree adds up.

Mulch for paths, slopes and odd-shaped beds

Paths and irregular beds are where estimates drift, because people guess the area instead of splitting it into shapes.

• Paths. Work out a path the same way as a bed, and ask your supplier how deep to lay it for foot traffic. For example, a 3 ft wide, 40 ft long path at 4 in is 120 ft² × 4 ÷ 324 = 1.48 yd³ (40 ft³), or 14 bags of 3 ft³. With 10% extra that is 1.63 yd³.
• L-shaped and wrap-around beds. Split them into rectangles that do not overlap, then add the areas. A 3 × 30 ft border plus a 3 × 15 ft return is 90 + 45 = 135 ft².
• Kidney and free-form beds. Measure the longest length and the average width (take three widths and average them). Length × average width is usually close enough for mulch, since the 10% extra absorbs most of the error.
• Slopes. Measure along the ground, not the flat plan distance, because the mulch lies on the slope surface. On steep banks, ask your supplier which product stays put best; fine, light mulch is the most likely to wash down.

Mulch in metric: litres and cubic metres

Outside the US, mulch is sold in litre bags and by the cubic metre. One centimetre of depth over one square metre is exactly 10 litres, so the arithmetic is simple: m² × depth (cm) × 10 = litres.

US bag sizes convert as 1.5 ft³ ≈ 42.5 L, 2 ft³ ≈ 56.6 L and 3 ft³ ≈ 85 L. If your bag is labelled in litres, divide the total litres by the bag size; if it is labelled in cubic feet, divide the total cubic feet instead.

Topping up old mulch: how much to order

Wood mulch breaks down and thins out, so most beds get a top-up rather than a fresh full layer. Order only the difference between the depth you want and the depth still there.

1. Push a trowel or ruler down in three or four spots until you hit soil, and average the readings.
2. Subtract from your target. A 3 in target over 1 in of old mulch needs 2 in.
3. Enter the difference as the depth in the calculator.

On a 300 ft² bed that change is significant: a full 3 in layer is 2.78 yd³ (38 bags of 2 ft³), while a 2 in top-up is 1.85 yd³ (25 bags). If the old layer is matted, rake it loose first so water still gets through, and remove any that has built up against stems or trunks before adding more.

How much does mulch weigh to haul?

Our calculator uses about 800 lb (0.4 US tons) per cubic yard of wood mulch, roughly 363 kg. That puts 2 yd³ at about 1,600 lb and 3 yd³ at about 2,400 lb before rain soaks in. The 40 ft³ path in the list above weighs about 1,185 lb dry. Fresh, wet or fine-ground mulch is heavier, so ask the supplier what their product weighs per yard and compare it with the payload on your vehicle’s door-jamb label before loading.

Common mistakes when ordering mulch

Most mulch orders go wrong on units or depth, not arithmetic. These are the errors that matter most, with what each one does to the order.

• Treating the bag size as coverage. A 2 ft³ bag does not cover 2 ft². At 3 in deep it covers 8 ft², and at 2 in it covers 12 ft². Divide the volume you need by the cubic feet on the bag.
• Entering depth in the wrong unit. Typing 3 into a feet field instead of inches multiplies the order by 12. A 200 ft² bed at 3 in is 1.85 yd³; at 3 ft it would be over 22 yd³. If a result looks huge, check the depth unit first.
• Adding an extra inch “to be safe”. Going from 3 in to 4 in on a 200 ft² bed raises the order from 1.85 yd³ to 2.47 yd³, a third more mulch that also sits deeper over roots. Add 10% for settling instead.
• Measuring the whole yard instead of the beds. Lawn, paths and paving inside the outline do not need mulch. Measure each bed and add the areas together.
• Ignoring last year’s mulch. If 1 in is still there, a 3 in target needs only 2 in more. On 200 ft² that drops the order from 1.85 yd³ to 1.23 yd³.
• Piling mulch against trunks. A cone of mulch around a tree keeps bark wet and uses mulch you did not plan for. Spread a flat ring and leave at least a hand’s width of bare ground around the trunk.

Mulch calculator vs other landscape calculators: which one to use

Use this page for loose organic cover spread over a bed: wood chips, bark or shredded hardwood sold by volume. Switch tools when the material or the job changes:

• Filling or building beds with soil: the topsoil calculator gives cubic yards and tons for lawns and in-ground beds, and the raised bed soil calculator works in cubic feet and bags for framed beds. Size the soil first, then mulch on top.
• Stone instead of wood: the river rock calculator and pea gravel calculator also return tons, because stone is often sold by weight. At our assumed densities a yard of stone weighs more than three times a yard of wood mulch.
• Just converting units: if you know the area and depth and only need yards, the square feet to cubic yards converter does that single step.