Soil Calculator for Massachusetts Raised Beds and Borders
Enter your project dimensions
Two ways to make a vegetable patch on the same stony back lawn. Build a pair of 4 by 8 ft raised beds and fill them a foot deep, and you need about 2.4 cubic yards of blended soil. Improve the same 64 square feet in the ground by working three inches of blend through the top of it, and you need about 0.6. Four times the material for the same growing area, and this soil calculator will give you either figure. The decision that matters is which one you are actually making.
Filling a box, or improving the ground you already have
Most of Massachusetts sits on stony glacial till. Digging a new in-ground bed here turns up rocks, and the instinct is to give up and build a box. That instinct is sometimes right and often expensive.
Raised beds win where the ground is genuinely unworkable, where drainage is poor over dense lower till, or where a gardener wants the height. They need filling to their full depth and refilling a little every spring, because a compost-rich blend keeps shrinking as the organic fraction breaks down.
Improving in the ground wins almost everywhere else. Two to three inches of compost-blended soil worked through the top six inches gives roots a graded transition instead of a hard edge, and the worms carry it deeper over a couple of seasons. It takes roughly a third of the material and a fraction of the wheelbarrowing.
A middle route works on poor ground: a low bed, six to eight inches of blend over loosened subsoil, with no sides at all.
Two beds, a border and a half barrel in one session
Choose rectangle, circle or multiple areas, up to five at once. Bed lengths and widths go in as feet, a round planter takes its diameter, and depth goes in as inches with anything from 0.25 to 24 accepted, which covers a topdress through to a filled bed.
Take the depth from the job rather than from the bed. Twelve inches fills an empty raised planter. Six inches builds a new in-ground bed. Four to six inches tops up a bed that has sunk over winter. Two to three inches is an amendment worked into existing soil.
Pick the material so the weight matches what you are ordering, leave the optional 5% for compaction and spillage ticked if you want the margin, and press calculate. Cubic yards, tons and cubic feet come back, and the email field will send them to you.
Run the round planter as its own circle calculation and add it to the total yourself. Keeping shapes separate is less error-prone than trying to average a barrel into a rectangle.
Why a bed that swallowed a pickup load reads as 2.4 tons
The volume arithmetic: square feet multiplied by depth in inches divided by 12 gives cubic feet, and cubic feet divided by 27 gives cubic yards. Garden soil is sold by the cubic yard, so that middle number is the one to order on.
The tonnage comes from the weight. Blended garden soil is published here at roughly 2,000 lb per cubic yard, a flat 1.00 tons per yard, which is the lightest thing in this catalogue apart from mulch. Screened loam runs heavier at about 2,200 lb, or 1.10 tons, and fill dirt heavier again at about 2,400 lb, or 1.20.
So the two beds: 64 sq ft at 12 inches is 64 x 12 / 12 = 64 cu ft, which is 64 / 27 = 2.37 cu yd, and at 1.00 tons per yard, 2.37 tons. Add a border 22 by 3 ft at 4 inches and you add 66 x 4 / 12 = 22 cu ft, taking the session to 86 cu ft, 3.19 cu yd and 3.19 tons. With the 5% ticked, 3.34 cu yd.
That near-parity between yards and tons is particular to garden soil. Run the identical volume as fill and the tonnage climbs by a fifth while the yardage does not move at all.
Ordering for the settling that happens by June
A compost blend settles. Somewhere around 10% goes in the first weeks as the organic fraction compacts and the watering starts, and a heavily planted bed can drop further over its first season.
Order for that rather than fight it. On the two beds above, 3.19 yards calculated means ordering three and a half, filling proud of the rim, watering thoroughly, then topping up once when it has sunk. The leftover is never wasted; there is always a planter or a thin patch of border waiting for it.
Plan the drop as carefully as the quantity. Three yards of damp blend is a wet, heavy pile that stains concrete and kills grass underneath it within days. Put a tarp down, choose a spot the wheelbarrow can reach without crossing soft spring lawn, and check the truck has clear access to it. Delivery is arranged at checkout by ZIP code.
Blend for the beds, loam for the lawn, fill for the hole
Massachusetts Rock Supply sells three soils that gardeners mix up, and the calculators are deliberately separate.
- Garden Soil is the compost blend for beds, planters and planting areas. It is what this page sizes.
- Screened loam is what landscapers here call topsoil: the growing layer for lawns and finish grading, sized on the topsoil calculator.
- Fill Dirt is mineral subsoil for raising grade and backfilling, with nothing in it for plants, sized on the dirt calculator.
The practical rule for a deep bed: anything over 18 inches does not need planting blend all the way down. Fill the lower third with fill dirt or coarse organic material that breaks down in place, and keep 8 to 12 inches of garden soil where the roots are, running the calculator once for each layer. Shredded mulch for the beds afterwards is a separate order again, at a much lighter weight per yard.
Common questions
I have a yardage. Which product page do I open?
Beds, planters and planting areas go to Garden Soil. A lawn or a finish grade goes to Top Soil. Anything below the growing layer goes to Fill Dirt. Set quantity and a delivery date on the product page you choose.
Three yards is arriving and the beds are in the back garden. Where should it go?
On a tarp, on the hard standing, as close to the wheelbarrow route as the truck can safely reach. Soil left directly on a lawn kills the grass under it in a few days and turns the spot to mud, and a loaded truck on soft ground in April leaves ruts you will be repairing later.
The result shows tons as well as yards. Which one do I use?
Order on the yards, since soil sells by the cubic yard. The tonnage tells you what is being moved, which matters if you are wheelbarrowing it any distance. For garden soil the two numbers are almost the same, which is why the tonnage can look implausibly low next to a stone order.
Should I enter the depth I want to end up with, or extra for settling?
Enter the finished depth you want. Handle settlement afterwards by rounding the order up and by filling proud of the rim, not by inflating the depth box, which makes the figure harder to check later.
The planter is a round half barrel. How do I work that out?
Circle mode, using the inside diameter across the top. A 4 ft barrel filled 16 inches deep is 12.6 sq ft, so 12.6 x 16 / 12 = 16.8 cu ft, which is 0.62 cu yd. Do the same for a tree ring you are topping up, measuring out to the edge of the mulch line.
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