Soil Calculator
Enter the length, width and fill depth of each raised bed, container or area and this calculator tells you exactly how much soil to buy — the number of bags, the order in cubic yards, cubic feet or litres, the estimated weight, and the cost. Everything runs in your browser; nothing you type leaves your device.
It is built for garden soil specifically. Pick a soil type (garden / raised-bed blend, potting or container mix, topsoil, compost, peat, coir, vermiculite or perlite) and it pre-fills a typical density, fill depth and bag size; tap a recommended-depth chip for a shallow, standard or deep bed, a lawn top-dress or a new bed; fill round, oval, rectangular or triangular containers; and compare buying by the bag against ordering in bulk. Every number stays editable.
The tool's differentiator is the soil-mix builder: turn the total volume into a named blend like Mel's Mix — or your own recipe — and it works out how much of each ingredient to buy as a shopping list. Add a bed for each area and the totals update live; switch between metric and imperial at any time and every value converts in place, or switch to Coverage mode to work backwards from soil you already have.
How to use the soil calculator
Soil volume is a footprint area multiplied by a fill depth. You can mix units — measure the bed in feet and set the depth in inches — and the calculator handles the conversion, which is the step most people get wrong by hand. It then adds a settling allowance (soil compacts after watering) so you order enough.
Choosing a soil type only sets sensible defaults for density and bag size; it never changes the covered area or the volume, because volume is pure geometry. Container jobs report in litres or quarts rather than cubic yards, so a pot never surfaces as a fraction of a yard you cannot buy.
How to calculate soil in 5 steps
- Choose unitsPick metric (m, mm, m³, litres) or imperial (ft, in, yd³, cu ft) at the top. You can switch later and every entry converts in place.
- Pick a soil typeChoose garden / raised-bed blend, potting or container mix, topsoil, compost, peat, coir, vermiculite or perlite to pre-fill a typical density, fill depth and bag size. The type changes only the weight and bag convention, never the volume — every value stays editable.
- Set the fill depthTap a recommended-depth chip — raised bed 6, 10 or 12 in, lawn top-dress 0.5 in, or a new bed at 3 in — or type your own. Chips fill any empty bed depths without overwriting depths you have typed. For containers, use the fill height up to a couple of inches below the rim.
- Add your beds and containersAdd a bed per area, choose its shape (rectangle, round, oval, triangle or area) and enter the dimensions. Totals sum across every bed and container.
- Read the resultsThe panel shows bags and order volume as the two headline numbers, plus cubic feet or litres, estimated weight, truckloads and cost. Turn on the soil-mix builder for a per-ingredient shopping list, enter a bag and a bulk price to see which is cheaper, then export CSV or print a plan.
Worked example: an 8 × 4 ft raised bed, 12 in deep
The classic question is “how much soil for an 8 by 4 raised bed, 12 inches deep?”. Convert the depth to feet first, multiply by the footprint, then divide by 27 — there are 27 cubic feet in a cubic yard — or divide the cubic feet by the bag size to count bags.
8 ft × 4 ft × 12 in = 1.19 yd³ (32 ft³ · 17 bags of 2 cu ft)
- Footprint area: 8 ft × 4 ft = 32 ft²
- Depth in feet: 12 in ÷ 12 = 1 ft
- Cubic feet: 32 ft² × 1 ft = 32 ft³
- Cubic yards: 32 ft³ ÷ 27 = 1.19 yd³
- Bags: 32 ft³ ÷ 2 = 16 bags of 2 cu ft
Build a soil mix: Mel's Mix and custom blends
Square-foot gardening's Mel's Mix is equal parts (by volume) compost, peat moss and vermiculite — and the calculator can split your total bed volume into exactly that, telling you how many bags of each to buy. Prefer a peat-free mix? The coco-coir variant swaps peat 1:1 for coconut coir. For a simple in-ground raised bed, the extension-cited blend is roughly half topsoil, half compost.
Turn on Split into a soil mix, pick a named blend or build your own recipe, and the ratios normalise automatically — 1 : 1 : 1 and 2 : 2 : 2 give the same split, so you never have to make them add up to 100. Each ingredient carries its own bag size, because peat bales, coir bricks and vermiculite bags ship in incompatible units.
Mel's Mix for a 4 × 4 ft bed, 6 in deep
8 ft³ total → about 2.7 ft³ each of compost, peat moss and vermiculite, then rounded up to whole bags per ingredient.
Peat and coir bales expand a lot when hydrated; bag counts use each product's rated expanded yield, not its compressed bale or brick size.
Soil for round and oval containers
Pots, half-barrels and oval planters are where cubic-yard tools fall down — you cannot buy a hundredth of a yard. Choose the Round or Oval shape, enter the diameter (or the two axes for an oval) and the fill height, and the calculator reports the fill in litres or quarts and rounds it up to whole bags. Round and oval bed geometry is a genuine gap in most competitor calculators.
A 50 cm pot filled to 35 cm ≈ 69 L → 2 bags of 40 L
Fill height is the soil depth inside the pot; leave a couple of centimetres below the rim for watering.
Bagged soil vs bulk delivery
Bags are convenient for a bed or two and easy to carry; bulk soil (by the cubic yard, delivered) is usually cheaper once a job runs to many bags, even after a delivery fee. Enter a bag price and a bulk price and the calculator shows both totals, tells you which is cheaper and by how much, and gives the break-even volume where bulk overtakes bags.
Bulk wins here — about $11.11 cheaper than bags.
Break-even ≈ 1.95 yd³: below that bags are cheaper, above it bulk pulls ahead.
Bag counts round up to whole bags; the delivery fee is a flat charge on the bulk order only.
Frequently asked questions
How much soil do I need?
Measure the length and width of each bed and pick a fill depth. Enter them (you can use feet for the bed and inches for the depth) and the calculator multiplies them, adds a settling allowance and totals every bed into one order in bags, cubic yards, cubic feet or litres. Add a bed for each separate area, container or pot.
How much soil for a raised bed?
Multiply the bed's length, width and fill depth. An 8 × 4 ft bed filled 12 in deep is 32 cubic feet — about 1.2 cubic yards, or sixteen 2 cu ft bags. A standard 4 × 8 ft bed at 6 in takes half that. The calculator does the unit conversion and adds about 10% for settling so the bed does not sink below the rim after the first watering.
How many bags of soil are in a cubic yard?
It depends on the bag size, because soil is sold by volume. A cubic yard is 27 cubic feet, so it is about 14 bags of 2 cu ft, 18 bags of 1.5 cu ft, or 27 bags of 1 cu ft. In metric, twenty 50-litre bags make roughly one cubic metre. The calculator counts bags by rounding your exact order up to whole bags for the size you pick.
How deep should a raised bed be?
Six inches suits herbs, lettuce and other shallow-rooted crops; eight to twelve inches covers most vegetables; and deep-rooted crops like tomatoes, carrots and potatoes prefer twelve inches or more. If the bed sits on open ground rather than a hard surface, roots can also grow into the soil beneath, so you can fill a little less deep.
What is in Mel's Mix?
Mel's Mix, from square-foot gardening, is equal parts by volume of compost, peat moss and coarse vermiculite — one third each. A peat-free version swaps the peat 1:1 for coconut coir. Turn on the soil-mix builder, pick Mel's Mix, and the calculator splits your bed volume into thirds and tells you how many bags of each ingredient to buy.
What is the difference between topsoil, garden soil and compost?
Topsoil is screened native soil — heavy, cheap and best for bulk filling or levelling. Garden or raised-bed soil is a lighter blend made for planting straight into. Compost is decomposed organic matter that feeds the soil and improves structure but is not used alone as a bed fill. A common raised-bed mix is roughly half topsoil (or garden soil) and half compost; pick the matching soil type so the weight estimate is right.
How much soil for a pot or container?
Choose the Round, Oval or Rectangle shape, enter the diameter (or the two axes for an oval) and the fill height, and the calculator reports the volume in litres or quarts and rounds it up to whole bags. A 50 cm pot filled to 35 cm holds roughly 70 litres — about two 40-litre bags. Container soil is sold in litres or quarts, so the tool never shows an unbuyable fraction of a cubic yard.
Should I buy soil in bags or in bulk?
Bags are convenient for a bed or two and easy to carry; bulk (by the cubic yard, delivered) is usually cheaper once a job runs to many bags, even after a delivery fee. Enter a bag price and a bulk price and the calculator shows both totals, tells you which is cheaper and by how much, and gives the break-even volume where bulk overtakes bags.
Does it work in metric and imperial?
Both. Switch units at the top and every dimension, volume, weight and price converts in place — depths in inches or millimetres, volume in cubic yards, cubic feet or litres, and bags in cubic feet, litres or US quarts. You can measure a bed in feet and set the depth in inches; the calculator handles the mix.
Is the calculator private?
Yes. Every calculation runs entirely in your browser. Nothing you enter is sent to any server, and your project is saved only in your own browser's local storage.