Raised Bed Soil Calculator
The raised bed soil calculator works out exactly how much soil you need to fill raised beds, planters, and pots. Enter your bed or container dimensions and it returns the volume in liters, cubic feet, cubic yards, and gallons, plus how many bags to buy.
Buying too much soil wastes money, and buying too little means another trip to the garden center. This tool gives you precise volume figures so you can order the right amount the first time. It handles three raised bed shapes (rectangle, circle, and L-shape) and three container types (round pot, square pot, and rectangular planter), and uses the frustum formula for tapered pots whose top is wider than the bottom.
How to Use the Soil Calculator
Choose your unit system
Switch between Metric (centimeters and liters) and Imperial (inches and cubic feet). Every value, including the bag sizes, updates instantly.
Select mode and shape
Pick Raised Bed (Rectangle, Circle, or L-Shape) or Container / Pot (Round Pot, Square Pot, or Rectangular Planter) to match what you are filling.
Enter your dimensions
Type the measurements for your bed or container. For an L-shaped bed, fill in Section A and Section B separately; for a tapered pot, enter both the top and bottom sizes.
Add more beds (optional)
Use Add Another Bed to plan a whole garden at once. Each bed shows its own volume and the total is combined automatically.
Read your results
See the total volume in several units, the number of bags needed for your chosen bag size, and a recommended soil mix broken down into topsoil, compost, and amendments.
Features
Multiple Bed Shapes
Calculate soil for rectangle, circle, and L-shape raised beds, covering the most common garden bed layouts.
Container & Pot Shapes
Fill round pots, square pots, and rectangular planters, with the right volume formula for each one.
Accurate Tapered-Pot Math
Most pots are wider at the top, so the calculator uses the frustum formula on both diameters for a true volume, not a rough cylinder estimate.
Multiple Beds at Once
Add as many beds or containers as you need. Each shows its own volume and the totals are summed automatically.
Bag Calculator
See how many bags to buy for common sizes: 25L, 40L, 50L, or 75L in metric, and 0.75, 1, 1.5, or 2 cubic feet in imperial.
Soil Mix Guide
Get a recommended 40% topsoil, 40% compost, 20% perlite/vermiculite mix with the exact volume for each component.
Multiple Volume Units
Read the total in liters, cubic meters, cubic yards, cubic feet, and gallons so the numbers match how soil is sold near you.
Metric & Imperial
Switch between centimeters/liters and inches/cubic feet with one click; every value and bag size updates instantly.
Frequently Asked Questions
How much soil do I need to fill a raised bed?
Multiply length by width by depth to get the volume. Enter those three measurements in the Rectangle shape and the calculator returns the exact amount in liters, cubic feet, cubic yards, and gallons, so you do not have to do the math yourself.
How do I measure my raised bed?
Measure the inside dimensions of the frame: from the inside edge of one side to the inside edge of the opposite side for length and width. For depth, measure from the bottom of the bed up to where you want the soil level to reach.
How many bags of soil do I need?
Pick your bag size and the calculator divides your total volume by it, rounding up to whole bags. Metric users can choose 25L, 40L, 50L, or 75L; imperial users can choose 0.75, 1, 1.5, or 2 cubic feet. For a large fill it is often cheaper to compare bagged bags against bulk soil sold by the cubic yard.
What if my pot is tapered?
Use the Round Pot or Square Pot shape and enter both the top and bottom measurements. The calculator applies the frustum formula to the taper, which is more accurate than using a single width for the whole pot.
How do I calculate an L-shaped bed?
The L-Shape option splits the bed into two rectangles, Section A and Section B. Measure each rectangle separately and enter one shared depth. The total volume is the area of both sections multiplied by that depth.
Is the 40/40/20 soil mix suitable for all plants?
The 40% topsoil, 40% compost, 20% perlite/vermiculite mix suits most vegetables, herbs, and flowering plants. Some plants need adjustments: succulents prefer more drainage (add perlite), while acid-loving plants like blueberries benefit from added peat moss.
Should I buy extra soil beyond what the calculator shows?
It is good practice to add about 10% on top of the figure shown. The calculator returns the exact geometric volume, but soil settles and compacts once it is watered, so a small buffer keeps your bed properly filled.
Why are the bag sizes different in metric and imperial?
Soil is sold in different standard sizes by region. Metric countries commonly stock 25L, 40L, 50L, and 75L bags, while US and other imperial markets sell by the cubic foot (0.75, 1, 1.5, or 2 cu ft). Switching the unit system shows the right set for you.
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