Soil Calculator: Filling Three Raised Beds in One Run
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Bed-filling season opens when the ground stops sticking to your boots, and in a Piedmont back garden that is usually weeks before the same job is workable up on the Garrett plateau. This page runs one job end to end, from marking out three new raised beds to topping them up a month later, with the soil calculator handling the middle of it. The material here is the blended growing mix that goes into beds and planters, not the lawn layer and not the structural fill under it.
Waiting for the ground before booking the delivery
Blended soil is at its best dry. Wet, it clumps on the shovel, smears through the bed instead of falling loose, and compacts under its own weight before a single root gets into it. Maryland gives you two decent windows: spring once the ground has drained, and early autumn after the worst of the summer storms. Low Coastal Plain gardens on the Eastern Shore and in Southern Maryland hold water longest, since flat land above a high water table sheds slowly.
Order for the week you plan to work. Have the pile tipped on a tarp rather than straight onto a drive, because soil stains concrete and the tarp turns clearing up into ten minutes instead of an hour.
Measuring three beds and the strip between them
Take the inside dimensions of each frame, not the outside, since the boards are not what you are filling. Three beds at 4 by 10 feet come to 40 square feet apiece. The strip of tired in-ground border between them measures 5 by 22 feet, another 110 square feet, and that is a separate job at a separate depth.
Where a bed is deeper than about 18 inches, split it in two while you have the tape out. The lower third can be fill or coarse organic material, with 8 to 12 inches of growing blend above it, and each of those layers is its own calculation.
Adding all four areas in a single calculation
Pick the multiple-areas option, which takes up to five pieces at once. Rectangle is right for a framed bed; circle asks for a diameter across the widest point and covers a round herb bed or a planter.
Lengths and widths go in as feet. Depth goes in as inches, anywhere from 0.25 to 24, so a 12-inch planter and a 3-inch top-up of an old border both fit on the same form. Choose the material before you press calculate, because that selection is what sets the weight. The box marked add 5 percent extra for compaction and spillage is worth ticking on anything crossing a lawn in a wheelbarrow. The result comes back as cubic yards, tons and cubic feet at once, and it can be emailed over as a written quote.
Twelve inches in the planters, three worked into the border
Three 4 by 10 beds filled to 12 inches: 120 square feet at a full foot is 120 cubic feet, which is 4.44 cubic yards. The border strip is 110 square feet at 3 inches, or 0.25 of a foot, so 27.5 cubic feet, which is 1.02 cubic yards. Together that is 5.46 cubic yards, and both of those are invented figures for the page rather than an order anyone placed.
Depth is a decision, not a guess. Empty raised planters take the full 12 inches. New in-ground planting areas want about 6. Tired beds do better with 4 to 6 inches of blend worked into what is already there than with a fresh layer laid on top, and on old ground, 2 to 3 inches turned into the upper 6 is often enough. Maryland ground pushes in two directions on this: Piedmont clay holds water too long, and Eastern Shore sand lets it go too fast, but the fix is the same compost blend worked in over a couple of seasons.
Reading the material select against the other two soil pages
| What is being filled on a Maryland lot | The listing to pick | This site's published weight |
|---|---|---|
| A raised planter or bed going straight into planting | Garden Soil | roughly 2,000 lb a cubic yard, 1.00 tons |
| The growing layer over a regraded or seeded lawn | Top Soil | roughly 2,200 lb, 1.10 tons |
| The lower third of a tall bed, or a low corner being raised | Fill Dirt | roughly 2,400 lb, 1.20 tons |
| A mulch layer over the finished bed | Shredded Mulch | roughly 600 lb, 0.30 tons |
All four are approximate figures from this site's own chart, and the order they sit in is not an accident: the more organic matter a material carries, the lighter the yard. That is also why the blend is the one that settles. Lawn depths and grading quantities belong on the topsoil calculator, and anything structural, such as closing a trench or lifting a grade, on the dirt calculator.
Filling, watering in and the top-up three weeks later
Fill each bed a little proud of the rim, water it thoroughly and leave it. Compost-rich blends settle somewhere between 10 and 20 percent in the first few weeks, which is why the beds you filled level in April sit an inch low by May. Keep back a wheelbarrow load, or round the order up, and expect to top up once.
In an in-ground bed, mix the first few inches into the native soil instead of leaving a clean boundary between imported and existing ground. Roots cross a gradual change; they stall at a sharp one.
What each of the three output figures is for
Cubic yards is the working number here, because blended soil is sold by the yard and that is the figure the quantity box wants. Tons tells you what is arriving on the truck, which matters if the pile has to sit on a lawn or a drive. Cubic feet is the small-job unit, useful when one planter needs finishing and a bag or two would do it.
By hand: multiply length by width in feet for the area, divide the depth in inches by twelve and multiply it through, then divide by twenty-seven. Multiply the yards by the figure for the material if you want the weight as well. Take the yardage to the listing, set the quantity and choose your date there; delivery is arranged at checkout by ZIP code, and the delivery page sets out what the driver needs at the far end. The layer that goes over the finished beds is sized on the mulch calculator.
Common questions
Do I enter the depth of the loose soil or the level it settles to?
Enter the finished level you want and plan for settling separately. Blended soil is not compacted the way base stone is, so there is no rolled figure to work to, but a compost blend loses 10 to 20 percent of its height in the first few weeks as the organic content consolidates. Fill proud, water it in and top up once rather than trying to build that allowance into the depth box.
One of the beds is a circle. How do I get a number for it?
Switch that area to the circle setting and enter the diameter in feet, measured straight across the middle. A 5-foot round herb bed covers about 19.6 square feet, and filled 10 inches deep that is 16.4 cubic feet, or 0.61 of a cubic yard. Add it alongside the rectangular beds in multiple-areas mode and the form totals the lot.
Can I work the figure out myself to check it?
Yes, and on rectangular beds it is quick. Multiply the two inside dimensions for square feet, divide the depth in inches by twelve and multiply it in for cubic feet, then divide by twenty-seven. For the three beds above: 120 square feet times 1 foot is 120 cubic feet, divided by 27 gives 4.44 cubic yards. If your figure and the form's figure disagree, the usual culprit is a depth entered in feet.
Why does the same twelve inches come out heavier in one material than another?
The volume never changes; the weight does, because the tool applies whatever the material select is set to. Those 4.44 cubic yards weigh about 4.4 tons as garden soil, 4.9 as screened topsoil and 5.3 as fill dirt, and barely 1.3 as shredded mulch. Set the material first, then read the ton line.
Is the 5 percent box enough of a margin on a bed job?
It covers spillage and the wheelbarrow, not settling, and settling is much the larger number here. Tick it, then round the order up on top. On the job above, 5.46 cubic yards is realistically a 6-yard order, and the spare will be wanted for the top-up a few weeks later or for the next planter.
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