Garden Soil Calculator
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How much topsoil, compost or mulch you need for a bed, lawn, pot or grow bag, in cubic yards, cubic meters, liters or bags.
Quick answer: To work out how much soil you need, multiply the area by the depth. For example, a 600 square foot lawn at 4 inches of topsoil needs 200 cubic feet, 7.4 cubic yards. Enter your length, width and depth below, or the volume of a pot or grow bag, for cubic yards, cubic meters, liters, bags, cost and weight. Penn State Extension gives 4 to 6 inches of firmed topsoil for a new lawn, and Iowa State Extension gives 2 to 4 inches for mulch.
Material needed
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📐 Formula
Volume = area x depth x number of beds x (1 + settling %). Feet and inches: cubic feet = square feet x inches / 12, cubic yards = cubic feet / 27. Meters: cubic meters = square meters x centimeters / 100, liters = cubic meters x 1,000. A round bed or pot has area = pi x diameter squared / 4. A container is its stated volume (1 US gallon = 0.1337 cubic feet = 3.785 liters). Bags = volume / bag size, rounded up. Weight = volume x the weight per cubic yard or cubic meter.
How to Use the Garden Soil Calculator
Choose the material, shape and units
Pick topsoil, compost, wood chip mulch or straw mulch. Then choose a rectangle, a round bed or pot, or a container by volume, and feet and inches or meters and centimeters.
Enter the size and depth
Type the length and width, or the diameter, and the depth. For a pot, grow bag or bucket, enter the volume of one container. Depth is required, because it changes the answer most.
Add the number of beds and a settling allowance if you want them
Both are optional. Blank means one bed and no allowance.
Add bag size, prices and weight if you want them
Optional inputs give a bag count, bagged and bulk costs in your currency, and a weight. Compost uses a typical density if you leave the weight blank.
Read the result
See the volume in cubic yards or cubic meters and in cubic feet or liters, with bags, costs and weight below.
How much soil do I need?
The amount of soil, compost or mulch you need is the area times the depth. In feet and inches, multiply the area in square feet by the depth in inches, divide by 12 to get cubic feet, and divide by 27 to get cubic yards. In meters, multiply the area in square meters by the depth in centimeters and divide by 100 to get cubic meters; one cubic meter is 1,000 liters. People search for this as a garden soil calculator, a garden dirt calculator, a yard soil calculator, a landscape soil calculator or a topsoil calculator. All of these names describe the same sum, and this page does it for beds, lawns, pots and mulch.
How deep should the layer be?
The depth is the number that changes the answer most, and it depends on the job. These figures come from extension service publications. The calculator asks you for a depth and does not guess one, so you can work to your own site and your supplier's advice.
| Use | Depth | Source |
|---|---|---|
| Compost top-dressing on a lawn | about 1/4 inch | Virginia Cooperative Extension |
| Topsoil or compost over sown lawn seed | 1/4 to 1/2 inch | University of Maryland Extension |
| Topsoil to establish a new lawn | 4 to 6 inches, firmed | Penn State Extension |
| Mulch in garden beds | 2 to 4 inches; keep it no more than 4 inches deep around trees and shrubs | Iowa State Extension |
| Shredded bark mulch | 2 to 3 inches | Iowa State Extension |
Garden bed soil calculator
For a garden bed, enter the length, width and depth of the soil you want to add. Choose "Bed or lawn" for a rectangle or "Round bed or pot" for a circle, and use the number of beds if you have several of the same size. For an in-ground bed, Iowa State Extension suggests adding a few inches of the soil mix, incorporating it into the existing soil, and repeating until the bed is filled, so there are no sharp layers. For a raised bed with sides, use the raised garden bed calculator, which adds a soil mix and a board count. This calculator has its own settling allowance field if you want extra for fill that will drop.
| Bed size | Depth | Volume | Cubic yards |
|---|---|---|---|
| 4 x 8 ft | 6 in | 16.0 cu ft | 0.59 |
| 4 x 8 ft | 12 in | 32.0 cu ft | 1.19 |
| 10 x 10 ft | 6 in | 50.0 cu ft | 1.85 |
| 3 x 6 ft | 10 in | 15.0 cu ft | 0.56 |
| 6 x 3 ft | 12 in | 18.0 cu ft | 0.67 |
Topsoil calculator for a lawn: new lawn, sod and overseeding
A new lawn needs a real layer of soil. Penn State Extension says a minimum of 4 to 6 inches of good-quality topsoil, measured after it has firmed or settled, is typically needed to establish good turf. That depth applies to topsoil under seed or sod. For overseeding or covering sown seed, University of Maryland Extension says to use only about 1/4 to 1/2 inch of topsoil or finished compost on top, and elsewhere caps compost or straw at about 1/4 inch and soil at about 1/2 inch, so stay near 1/4 inch with compost. And for top-dressing an established lawn with compost, Virginia Cooperative Extension recommends about 1/4 inch. Because the depths differ by a factor of ten or more, enter the depth for your job.
Worked example: how much topsoil for a 600 square foot lawn
A lawn 30 ft by 20 ft is 600 square feet. At 4 inches of topsoil, that is 600 x 4 / 12 = 200 cubic feet, or 7.4 cubic yards. With a 10% allowance for settling it is 220 cubic feet, 8.1 cubic yards. In metric, a lawn 10 m by 6 m is 60 square meters; at 10 cm deep that is 6 cubic meters, or 6,000 liters. Choose "Bed or lawn", enter the size and the depth, add the settling allowance, and the calculator returns the same figures.
How much soil do I need for pots, grow bags and buckets?
For a pot, grow bag or bucket, use the volume. Choose "Container by volume", enter the size in US gallons or liters, and set the number of containers. For a round pot, choose "Round bed or pot" and enter the diameter and depth. Container sizes are nominal, and a pot is rarely filled to the very top, so treat the figure as the most you will need. The table shows common sizes.
| Container | Soil volume | In liters |
|---|---|---|
| 5 gallon bucket | 5 gal = 0.67 cu ft | 18.9 liters |
| 10 gallon grow bag | 10 gal = 1.34 cu ft | 37.9 liters |
| 15 gallon grow bag | 15 gal = 2.01 cu ft | 56.8 liters |
| 20 gallon grow bag | 20 gal = 2.67 cu ft | 75.7 liters |
| 12 inch pot, 12 inches deep | 5.9 gal = 0.79 cu ft | 22.2 liters |
| 30 cm pot, 30 cm deep | 5.6 gal = 0.75 cu ft | 21.2 liters |
Mulch: how deep and how much
Iowa State Extension says 2 to 4 inches of mulch is generally effective, with coarser mulches such as wood chips at the higher end and finer ones at the lower end, and recommends keeping mulch no more than 4 inches deep and feathering it away from the trunks of woody plants. It gives 2 to 3 inches as best for shredded bark. Pick a mulch in the material list to see a depth guide, then enter your own depth. Mulch is lighter and bulkier than soil, so bag sizes are often larger.
Worked example: 100 square feet of wood chip mulch at 3 inches
100 square feet at 3 inches deep is 100 x 3 / 12 = 25 cubic feet. That is 0.93 cubic yards. In 2 cubic foot bags that is 13 bags (12.5 rounded up). In your currency, if a bag costs 4.50, 13 bags cost 58.50; if bulk costs 35 per cubic yard, 0.93 cubic yards costs 32.41. The prices are only an illustration; enter your own.
Settling and compaction allowance
Loose fill compacts as it is watered and as the season's rain falls on it, so the level drops after you fill a bed. The calculator has an optional settling allowance in percent, added to the volume. There is no single figure that fits every material and mix, so the field is yours to set. A mix with a lot of compost in it settles more than a mineral topsoil, and your supplier or the product label is the best guide. Leave it blank to see the exact volume.
Bags, bulk or delivery
Bags are convenient for small jobs and bulk is cheaper per cubic yard for large ones. To compare, divide your bag price by the bag size to get the price per cubic foot or liter, and multiply by 27 for cubic yards, or by 1,000 for cubic meters when you work in liters, to compare with a bulk price. A cubic yard is 27 one-cubic-foot bags. Enter the bag size, bag price and bulk price in the calculator and it shows both costs side by side. Delivery charges are not included, so add them for bulk.
Weight of soil, compost and mulch
Bulk material is sold by volume and delivered by weight. The calculator shows the weight when it knows the density. For compost it uses about 1,000 pounds per cubic yard, which is Oregon State University Extension's rule of thumb for screened compost at 50% moisture, and it varies with moisture and compaction. For topsoil, mulch and other materials the weight depends on moisture and type, so enter your supplier's figure in pounds per cubic yard or kilograms per cubic meter.
Soil calculator in liters, cubic meters and metric tons
Choose meters and centimeters to work in cubic meters and liters. To convert a volume to metric tons, multiply cubic meters by the density in metric tons per cubic meter from your supplier. Use the table to compare a bulk load quoted in cubic yards with one quoted in cubic meters, or a bag labeled in liters with one labeled in cubic feet.
| From | To |
|---|---|
| 1 cubic yard | 27 cubic feet = 0.765 cubic meters = 765 liters |
| 1 cubic meter | 1,000 liters = 35.3 cubic feet = 1.31 cubic yards |
| 1 cubic foot | 28.3 liters = 7.48 US gallons |
| 1 US gallon | 3.79 liters = 0.134 cubic feet |
Using this calculator in the US, UK, Australia and Canada
In the US, bagged topsoil and mulch are sold by the cubic foot and bulk loads by the cubic yard, so the default feet and inches setting fits. Canada uses both systems, so match your supplier's bag label and bulk unit. In the UK and Australia, bags are sold in litres and bulk topsoil or mulch by the cubic metre or by the tonne, so choose metres and centimetres, and ask the supplier for the weight per cubic metre to turn volume into tonnes. The words differ too: dirt, topsoil, garden soil and loam are used for similar things, and yard and garden are used for the same space. Prices and bag sizes vary by supplier, so you enter your own.
Related garden calculators
For compost on its own, with a lawn top-dressing preset and a browns to greens check, use the compost calculator. For a raised bed with a board list, use the raised garden bed calculator. After the soil is in, the plant spacing calculator shows how many plants fit, and the garden watering calculator turns the bed size into a weekly water figure.
Frequently Asked Questions
Multiply the length, width and depth of the fill, then add a settling allowance if you want one. The raised garden bed calculator adds a soil mix and a board count for beds with sides.
A 4 ft by 8 ft bed is 32 square feet, so every inch of depth takes 2.67 cubic feet. The raised garden bed calculator has the soil mix and board list for that size.
A bed 6 ft long, 3 ft wide and 1 ft deep holds 18 cubic feet, which is 0.67 cubic yards or about 510 liters. If you work in meters, a bed 1.8 m by 0.9 m and 30 cm deep is about 0.49 cubic meters.
Multiply one container's volume by the count. Twelve 5 gallon buckets come to 8.0 cubic feet, about 0.30 cubic yards, and a single 20 gallon grow bag is 2.67 cubic feet. Round up to whole bags when you buy bagged mix.
Choose round bed or pot, enter the diameter and the depth of soil, and the calculator works out the volume of the cylinder. Measure the depth of soil, not the height of the pot, so you leave room below the rim for watering.
Lay a straight board or string line across each dip, then measure down to the soil at the deepest point and at the edges. Enter the average of those readings as the depth. If several dips are about the same size, enter one and set the number of beds, then add a settling allowance because the fill will drop.
Enter only the depth you need to add, not the total depth. If the yard already has some topsoil, subtract it from the 4 to 6 inch target. For a 100 square meter lawn at 10 cm that is 10 cubic meters, or 10,000 liters.
At the 1/4 inch that Virginia Cooperative Extension gives for top dressing, 1,000 square feet takes 20.8 cubic feet, or 0.77 cubic yards. Topsoil over sown seed can go to about 1/2 inch, which would double the order to 1.54 cubic yards, but compost stays at about 1/4 inch.
Enter the lawn's length and width in feet, the depth in inches, and choose topsoil. The result is in cubic yards and cubic feet. For weight, enter your supplier's pounds per cubic yard and the calculator shows pounds and US tons. In meters, enter kilograms per cubic meter to get metric tons.
Choose meters and centimeters. Area is in square meters, depth in centimeters, and the answer is in cubic meters and liters. A depth of 1 cm over 1 square meter is 10 liters.
Each inch of mulch over 100 square feet takes 8.3 cubic feet, about 0.31 cubic yards, so going from 2 to 4 inches doubles the order.
Topsoil is the upper layer of mineral soil, garden soil is usually topsoil blended with organic matter, and compost is decomposed organic matter. Suppliers use the names loosely, so check what a product contains. The material list sets the depth guide and the result note, and compost also gets a typical weight.
Yes. The allowance is added to the volume before bags, cost and weight are worked out, so 10% on a 32 cubic foot bed gives 35.2 cubic feet, which is 36 one-cubic-foot bags instead of 32.
Divide the bag price by the bag size and multiply by 27 to get a price per cubic yard. A 1 cubic foot bag priced at 6 (in your currency) works out to 162 per cubic yard, so a bulk price below that wins before delivery, which is extra.
Sources & Methodology
Depth and mix guidance comes from named extension publications. Read as text on 2026-10-04: Virginia Cooperative Extension (Prince William County Office), "Composting the Lawn", adapted from The Weekend Gardener website, for about 1/4 inch of compost on a lawn; University of Maryland Extension, "Starting a New Lawn", for 1/4 to 1/2 inch of topsoil or finished compost over sown seed; Iowa State Extension, "Using Mulch in the Garden", for 2 to 4 inches of mulch and no more than 4, and 2 to 3 inches of shredded bark; Iowa State Extension's raised bed soil mix FAQ for working a soil mix into the existing soil. Penn State Extension, "Lawn Establishment", is the source for a minimum of 4 to 6 inches of firmed topsoil; automated tools could not retrieve that page on 2026-10-04, so the figure is quoted from Penn State's search listing. The 0.77 cubic yards per 1,000 square feet in the top dressing FAQ is our own arithmetic from Virginia's 1/4 inch. The compost density of about 1,000 pounds per cubic yard is from Oregon State University Extension EM 9217.
The volume arithmetic and the conversions between cubic yards, cubic feet, cubic meters, liters and gallons are exact. The weights of topsoil and mulch are not given, because they vary with moisture and type; the field takes your supplier's figure. Prices, bag sizes and the settling allowance are whatever you enter.
- Virginia Cooperative Extension: Composting the Lawn (adapted from The Weekend Gardener)
- University of Maryland Extension: Starting a New Lawn
- Penn State Extension: Lawn Establishment
- Iowa State Extension: Using Mulch in the Garden
- Iowa State Extension: What would be a good soil mix for a raised bed?
- Oregon State University Extension: Interpreting Compost Analyses (EM 9217)