Soil volume calculator
Filling a raised bed, planter or row of pots? Enter the dimensions and GrowGuide converts them into the soil you need — in cubic feet, cubic yards, litres and the number of bags to buy.
Bed or container
Soil needed
Buy a little extra — soil settles by roughly 10–20% once watered in.
How to measure for soil
Pick the shape
Choose a rectangular box for most raised beds and planters, or round for barrels, fabric pots and circular beds. The right fields appear automatically.
Enter size and depth
Measure the inside dimensions and how deep you actually want the soil to sit. Add a quantity if you are filling several identical containers at once.
Order with confidence
Read the total in whichever unit your supplier uses, and the bag count based on the size you buy. Round up so you are never a scoop short.
Why estimate before you buy
Skip the second trip
Bagged soil is heavy and awkward. Knowing the count up front means one load instead of a frustrating return trip when the bed swallows more than you guessed.
Bulk versus bags
Above roughly one cubic yard, loose delivery is usually cheaper and greener than dozens of plastic sacks. The cubic-yard figure tells you when to make the switch.
Nothing tracked
Every figure is worked out in your browser. There is no account and no data leaves your device, so plan as many beds as you like in private.
Working out soil volume
Soil volume is simply the space inside your bed or pot: length times width times depth for a box, or the area of the circle times the depth for anything round. The maths is easy — the awkward part is that beds are measured in feet, depth in inches and soil is sold in litres or cubic yards. This tool keeps every unit straight so you can compare a bagged price against a bulk delivery without doing conversions by hand.
How deep should the soil be?
Shallow-rooted salads and herbs are happy in 15–20 cm (6–8 inches). Most vegetables prefer 30 cm (12 inches), and deep feeders like tomatoes, carrots and potatoes reward you with 40 cm or more. If you are topping up an existing bed rather than filling from scratch, measure only the gap you need to fill.
Allow for settling
Fresh mixes are fluffy and full of air. After the first few waterings they compact, and a bed filled exactly to the brim can drop a couple of centimetres. Ordering about 10–20% more than the bare calculation covers that settling and leaves a little to top up later in the season.
Bags or bulk?
A standard bag of potting mix is often 1.5 cubic feet or around 40–50 litres, while garden soil bags vary widely — always read the label and enter that figure. Once you need more than about a cubic yard (roughly 765 litres), a bulk delivery is usually cheaper per litre and saves a mountain of empty plastic.
Frequently asked questions
How is soil volume calculated?
For a rectangular bed it multiplies length by width by depth. For a round container it uses the circle area — pi times the radius squared — times the depth. Every measurement is converted to a common unit first, then the total is shown in cubic feet, yards, metres, litres and gallons.
How many bags of soil will I need?
Enter the size printed on the bag you plan to buy and the calculator divides the total volume by it, rounding up. If your bag is measured in litres or gallons, switch the bag unit menu to match.
Should I add extra for settling?
Yes. Loose mixes compact by roughly 10–20% after watering. Ordering a little more than the exact figure keeps the bed topped up through the season.
Can I calculate several containers at once?
Enter the size of one container and set the quantity to how many identical ones you are filling. The total and bag count cover them all, and the per-container figure shows the volume of a single one.
What is a cubic yard in bags?
One cubic yard is 27 cubic feet, so it takes eighteen 1.5-cubic-foot bags to equal a single yard. That is why bulk delivery usually wins once you pass roughly a cubic yard.
Is my data uploaded?
No. The calculation runs entirely in your browser with no account and no server, and the page keeps working even with your connection turned off.