Free Mulch Calculator
Turn garden measurements into bags, cubic yards and costs.
Imperial or metric. One bed or a whole garden.
Start with one bed. Add more if you need to.
Rectangles, circles, tree rings and more. One bed or your whole garden, all in one plan.
Get whole-bag quantities and compare bulk prices, including delivery, before you buy.
Account for mulch already on the ground. Buy what you need to reach your target depth.
A little know-how goes a long way
A few simple choices make all the difference.
01 / Find your depth
For many beds, start with 2–3 inches (5–7.5 cm) of organic mulch in total. Finer material and sensitive plants may need less. Coarse mulch can call for a different depth.
Leave a clear gap around stems and trunks. Around trees, keep mulch about 3 inches from the trunk and avoid piling it over the root flare.
02 / Freshen things up
Measure the layer that is still there before buying more. The target is your finished depth, including existing mulch.
Open “Top-up & extra allowance” in the calculator. It works out the new layer for you and never gives a negative quantity.
Plan your top-upSimple maths. Clear answers.
Area × depth gives you volume. We handle the unit conversions and round your shopping quantities up.
A 20 × 5 ft bed is 100 ft². At 3 inches deep: 100 × 3 ÷ 324 = 0.926 yd³. That is 25 ft³, or 13 whole 2-ft³ bags.
A 5 × 2 m bed is 10 m². At 5 cm deep: 10 × 5 ÷ 100 = 0.5 m³. That is 500 litres, or 10 bags of 50 litres.
A quick reference for common US and UK bag sizes.
| Bag size | At 2 in / 5 cm | At 3 in / 7.5 cm | Bags per yd³ / m³ |
|---|---|---|---|
| 1.5 ft³ | 9 ft² | 6 ft² | 18 per yd³ |
| 2 ft³ | 12 ft² | 8 ft² | 14 per yd³* |
| 3 ft³ | 18 ft² | 12 ft² | 9 per yd³ |
| 50 litres | 1 m² | 0.67 m² | 20 per m³ |
| 60 litres | 1.2 m² | 0.8 m² | 17 per m³* |
| 100 litres | 2 m² | 1.33 m² | 10 per m³ |
US bags use 2 and 3 inch depths; litre bags use 5 and 7.5 cm. *Whole bags rounded up. No extra allowance included. “Bulk bags” sold by weight need a stated volume from the supplier before they can be used here.
A mulch calculator turns the size of your garden beds and your chosen layer depth into a volume you can buy. Free Mulch Calculator shows cubic yards, cubic feet, cubic metres, litres and whole bags together. Use it for a new flower bed, a border around a lawn or a seasonal refresh. You can combine several beds, account for existing mulch and compare bagged material with a bulk order before visiting a store or contacting a supplier.
Choose US / Imperial or UK / Metric, then select your bed shape. Enter length and width for a rectangle, diameter for a circle, or inner and outer diameters for a tree ring. Choose Known area if you already have the square footage. Add other beds or increase Identical beds for repeated sections. Set your desired total depth, check the result and open the optional settings to enter bag capacity, current mulch depth, extra allowance or local prices.
The estimate updates as you type. All beds share the same depth settings, so calculate separate plans when different sections need different layers. Read our calculation method to see the geometry and unit conversions behind the results.
For a rectangular bed, multiply length by width to get square feet. A 20-foot-long bed that is 5 feet wide covers 100 square feet. In a mulch calculator, square feet describe the surface area; depth determines how much material fills that space. The same bed requires twice as much mulch at 4 inches as it does at 2 inches. Measure the area you will actually cover, excluding patios, paths and other unmulched sections.
For an irregular border, divide it into non-overlapping rectangles, circles or triangles and add them as separate beds. Use decimal feet for partial measurements: 10 feet 6 inches is 10.5 feet. Avoid counting overlapping sections twice.
When suppliers sell mulch by the “yard,” they usually mean a cubic yard, a measure of volume. One cubic yard equals 27 cubic feet. A square yard measures area and cannot tell you how much mulch to order without a depth. To calculate cubic yards from square feet and inches, use: area × depth ÷ 324. For the 100-square-foot bed at 3 inches, that gives 100 × 3 ÷ 324 = approximately 0.93 cubic yards.
Use the exact volume estimate when requesting a quote, then check the supplier’s order increments and minimum delivery quantity. The optional bulk settings round your order up to the increment you enter.
Divide the total volume by the volume printed on one bag, then round up to a whole bag. Our example needs 25 cubic feet: that means 17 bags of 1.5 cubic feet, 13 bags of 2 cubic feet or 9 bags of 3 cubic feet. Changing bag size changes the bag count, not the amount needed to cover the bed. The calculator adds all bed volumes before rounding, so separate partial bags are not rounded up unnecessarily.
Depth also changes coverage per bag. A 2-cubic-foot bag covers 12 square feet at 2 inches or 8 square feet at 3 inches. For metric bags, 50 litres covers 1 square metre at 5 cm. Check the mulch bag coverage table for more sizes.
Use the mulch cost calculator by opening Bag size & cost comparison and entering your local prices. Bagged material cost equals whole bags × price per bag. Bulk cost equals the rounded order volume × price per bulk unit, plus the delivery fee you enter. Choose the supplier’s pricing unit and order increment so the comparison reflects what you can actually purchase.
For example, our 100-square-foot bed at 3 inches needs 13 bags of 2 cubic feet. At an illustrative $4 per bag, that costs $52. A supplier selling half-yard increments would round 0.93 cubic yards up to 1 yard. At an illustrative $40 per yard plus $20 delivery, bulk costs $60. Replace these example prices with your own quote. Tax, spreading labour and any bag delivery charges need to be budgeted separately.
A mulch coverage calculator connects the volume you buy with the ground area it covers at your chosen depth. Coverage in square feet equals cubic feet × 12 ÷ depth in inches. One cubic yard contains 27 cubic feet, so it covers 162 square feet at 2 inches, 108 square feet at 3 inches or 81 square feet at 4 inches. A thicker layer covers less ground with the same amount of material.
For metric measurements, coverage in square metres equals litres ÷ (depth in centimetres × 10). A 50-litre bag therefore covers 1 square metre at 5 cm. Use the coverage table to check common bag sizes, then enter your bed area and depth in the calculator to find the required volume and whole-bag quantity. These figures assume an even layer with no extra allowance.
A rubber mulch calculator uses the same area × depth volume formula as other loose materials. Enter the depth specified for your product and application, plus its stated bag volume. Do not convert a bag’s weight in pounds or kilograms directly into cubic feet: density and packaging vary. If the label gives only weight, ask the manufacturer for volume or coverage at a specified depth. Landscape depth presets are general garden examples, not rubber surfacing specifications.
Use the tool as a playground mulch calculator only after choosing an appropriate surfacing material and its required installed depth. Measure the full equipment use zone, not just the footprint of a slide or swing. The U.S. Consumer Product Safety Commission’s playground surfacing resources explain the relevant standards. Follow the product’s tested fall-height rating, installation and maintenance instructions, and applicable local requirements. This calculator estimates volume; it does not certify fall protection. Do not use the 2–4 inch garden presets to select a playground depth.
Measure the existing layer before refreshing a bed. With 1 inch remaining and a 3-inch target, you need 2 inches of new mulch. Enter both depths in Top-up & extra allowance. Add a measured allowance for uneven beds if needed; it increases the purchase volume, not the target layer depth. Compare whole-bag costs with bulk order rounding and delivery. Tax and spreading labour are separate. Calculate your mulch quantity, then share or print the plan for your shopping trip.
A few things worth knowing
From your first bag to your next garden refresh.
Use the mulch calculator above to enter your bed shape, measurements and desired depth. It estimates cubic feet, cubic yards and whole bags. For example, 100 square feet covered 3 inches deep needs 25 cubic feet, or about 0.93 cubic yards: 13 whole 2-cubic-foot bags before any extra allowance. For an existing bed, enter the current mulch depth to calculate only the top-up.
A yard of mulch usually means one cubic yard, or 27 cubic feet. It covers 162 square feet at 2 inches deep, 108 square feet at 3 inches or 81 square feet at 4 inches. Coverage in square feet equals 324 divided by depth in inches. These figures assume an even layer without extra allowance for uneven ground or settling.
For many garden beds and tree or shrub plantings, 2–3 inches (about 5–7.5 cm) is a useful starting point. Depth depends on the mulch texture, plants and drainage. Keep mulch away from stems and tree trunks, and include the existing layer when measuring total depth.
One cubic yard of mulch contains 27 cubic feet. A cubic yard is a volume measuring 3 feet long × 3 feet wide × 3 feet high. Multiply cubic yards by 27 to get cubic feet, or divide cubic feet by 27 to get cubic yards. A square yard measures area and requires a depth before you can calculate mulch volume.
Measure each garden bed and choose its shape in the calculator. For a rectangle, length × width gives the area. In US units, cubic feet = area in square feet × depth in inches ÷ 12; cubic yards = area × depth ÷ 324. A 20 × 5 foot bed at 3 inches needs 25 cubic feet, or about 0.93 cubic yards. Add separate sections for irregular beds without counting overlaps twice.
Divide the required mulch volume by the volume printed on one bag, then round up to a whole bag. Enter the bag size in the mulch calculator to do this automatically. For a 100-square-foot bed at 3 inches deep, you need 25 cubic feet: 17 bags of 1.5 cubic feet, 13 bags of 2 cubic feet or 9 bags of 3 cubic feet, without extra allowance.
One cubic yard contains 27 cubic feet. It equals 18 bags of 1.5 cubic feet, 13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet. To buy enough in whole 2-cubic-foot bags, round up to 14.
Exactly 13.5 bags of 2 cubic feet equal one cubic yard: 27 ÷ 2 = 13.5. Buy 14 whole bags to have enough. Fourteen bags contain 28 cubic feet, leaving 1 cubic foot extra when you use exactly one cubic yard.
The best depth depends on the material and planting. A total layer of 2–3 inches works for many organic-mulch beds, while fine mulch and shallow-rooted plants may need less. Count existing mulch toward that total and keep the tree root flare uncovered. More mulch is not always better; an overly thick layer can cause root problems.
There is no fixed weight for a bag of mulch. Bag volume, material and moisture all matter, and wet mulch can be much heavier than dry mulch. Check the product label or ask the supplier for its weight. For illustration, if your chosen 2-cubic-foot bag weighs 30 pounds, 14 bags weigh 420 pounds. Use the stated bag volume, rather than weight, to calculate coverage.
Choose mulch for your plants and site. Bark is a common choice around trees and shrubs; shredded leaves also work as organic mulch and improve soil as they decompose. Pine needles are another option. Gravel or stone suits some rock gardens. Consider drainage, texture and maintenance, then use a depth appropriate for that material and planting in the calculator.
A cubic yard of wood or bark mulch may weigh roughly 400–800 pounds (about 180–360 kg), but this is only a planning estimate. Material, moisture and compaction change the weight; some suppliers quote around 900 pounds per cubic yard. Ask your supplier for the weight of the actual product before arranging transport. A cubic yard always contains 27 cubic feet, regardless of its weight.