Pea Gravel Calculator: Two Inches, or Twelve
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The same rounded 3/8 inch stone goes under a swing set at a foot deep and across a garden path at two and a half inches, and the orders are not remotely the same size. That is the decision the pea gravel calculator is really helping with. Give it a footprint and a depth and it returns cubic yards, tons and cubic feet, and the depth you pick for the job in front of you is what separates a ton from ten.
Which surface am I covering: a path, a patio or a fall zone?
Measure the finished surface, edge to edge, in feet. Rectangle mode covers paths, dog runs and play areas. Circle mode wants the diameter straight across, which is the setting for a fire pit surround. Multiple areas takes up to five at once, which is what a path, a side gate strip and a bin standing usually add up to.
Take a side path 3 feet wide and 28 feet long as a worked example, invented for this page. That is 84 square feet before any depth is chosen.
If the surface is going in within 1,000 feet of tidal waters or tidal wetlands, check the lot before you measure it. That band is the Chesapeake and Atlantic Coastal Bays Critical Area, and lot coverage there explicitly includes ground covered with gravel, stone, shell, pavers and permeable pavement, so a gravel pad counts against the cap exactly as a roof does. The cap is 15 percent in a Limited Development Area and tighter in a Resource Conservation Area, and it is your county's Critical Area program that administers it, so ask them rather than assuming one figure applies everywhere.
How deep before it goes soft underfoot?
Under 2 inches the ground shows through. Over 3 and it starts to feel loose when you walk on it. That narrow band holds for everything people stand on, and then play equipment breaks the rule entirely.
| The surface | Depth to enter | What decides it |
|---|---|---|
| Garden path or side walk | 2 to 2.5 inches | Thin enough to stay firm, deep enough to hide the base |
| Patio or seating area | 2 to 3 inches over 2 inches of compacted screenings | The screenings are what stop chair legs sinking |
| Fire pit surround | 3 inches | Nothing combustible, and it drains overnight after a storm |
| Dog run | 2 to 3 inches | Rounded stone is kind to paws and washes clean |
| Playground fall zone | 9 to 12 inches, maintained | The equipment manual sets this, not the landscaping |
Depth goes in as inches and the form accepts 0.25 to 24, so a fall zone at the top of its range is still well inside what the tool handles. One thing the table cannot tell you: this is landscape pea gravel and it is not sold as certified playground surfacing. The required depth, the fall-zone footprint and the maintained depth all come from the equipment manufacturer's instructions rather than from us.
The path example at 2.5 inches: 84 square feet by 0.2083 of a foot is 17.5 cubic feet, which is 0.65 cubic yards, or about 0.91 tons. A swing set fall zone 15 feet square at 10 inches is 225 square feet by 0.8333, or 187.5 cubic feet, which is 6.94 cubic yards and roughly 9.72 tons. Same stone, same yard, one order eleven times the other.
Why does something this small still weigh 2,800 pounds a yard?
Because rounded pieces pack closer than they look like they should. This site publishes 3/8 inch pea gravel at about 2,800 lb per cubic yard, which is 1.40 tons, the same line as #57 and 3/4 inch crushed stone. The figure is approximate.
What that means in coverage is easier to picture than the weight is.
| Depth for a Maryland job | One cubic yard covers | One ton covers |
|---|---|---|
| 2 inches, a garden path | 162 sq ft | about 116 sq ft |
| 3 inches, a fire pit ring or patio | 108 sq ft | about 77 sq ft |
| 4 inches, a well-used dog run | 81 sq ft | about 58 sq ft |
| 12 inches, a play area fall zone | 27 sq ft | about 19 sq ft |
A circle is the one shape worth checking by hand. A 10 foot fire pit ring covers 78.5 square feet, and at 3 inches that is 19.6 cubic feet, 0.73 cubic yards, or a little over a ton.
Is the 5 percent box worth ticking on stone that never packs down?
Tick it, for spillage rather than compaction. Rounded stone does not consolidate the way a blend with fines in it does, so the allowance is covering what ends up on the tarp, on the lawn and in the wheelbarrow wheel ruts rather than any settling.
Where it will not save you is at the edges. Rounded stone travels. Set steel, aluminum, timber or paver edging so its top sits about an inch above the finished surface; edging flush with the gravel lets the stone walk straight over it. On anything steeper than about a 5 percent grade the material moves downhill with rain and foot traffic whatever the edging does, and Maryland gets the rain to prove it. On a slope, either put a honeycomb stabilizing grid under the stone or switch to an angular material that locks together.
Bare feet, a slope, or a bed nobody walks on?
Three products cover overlapping ground and the choice is about traffic and grade, not looks.
- Bare feet, level ground, a patio or a fire pit ring: 3/8" Natural Pea Gravel, sized here.
- A sloping path or a route that gets real traffic: Walkway Gravel, angular so it interlocks, run through the gravel calculator.
- Beds, borders and dry creek beds where nobody walks: River Rock, which is larger and heavier per yard, sized on the river rock calculator.
Enter the same footprint in two of them and the cubic yards come back identical while the tons differ, which is the comparison worth having before you commit.
If the surface is a patio, order the base at the same time. Two inches of compacted stone dust underneath is what keeps furniture from sinking, and it is a separate line and a separate calculation.
Getting it to the right end of the garden
Take the tonnage to the product listing, set the quantity and choose a date. Delivery is arranged at checkout by ZIP code, and the delivery page covers what the truck needs where it tips. Rake a path level twice a year, and keep a bucket or two back to top up the line everybody actually walks on.
Common questions
How close will the estimate be once the stone is actually down?
The arithmetic is exact and the depth never quite is. Spreading rounded stone by rake leaves it thicker in some places than others, and the surface settles slightly in its first weeks of use, so real coverage tends to land a few percent short of the calculation. Measure the area properly, order the round-up, and keep the surplus rather than aiming for a figure to the pound.
I have my tonnage. Which listing do I open?
The 3/8" Natural Pea Gravel page, where the quantity and the delivery date are set. If the job is a patio and the base is going in at the same time, run the screenings depth as its own calculation and add that product as a second line on the same order.
Where do ten tons go when the play area is behind the house?
Somewhere firm, with clear headroom, as close to the work as a loaded truck can safely get. Stone on a lawn leaves a bare patch, so a drive with a tarp under it is better, and a pile that has to cross a lawn wants boards laid for the wheelbarrow. Walk the route and measure the gate before the order goes in, because ten tons is a great many wheelbarrow loads to reroute on the day.
The result gives yards and tons. Which one is the order?
Tons, for this material. The cubic yard figure is the volume the excavation has to hold, which is what to check the dig against, and it is also the figure to compare when you are weighing this stone against a heavier one for the same footprint. Cubic feet is useful only on the small strips.
Should the depth I enter be the loose depth or the settled one?
The finished depth you want to walk on. This material barely compacts, so the two are close, and the small amount it does settle is covered by ordering the round-up. On a fall zone the figure is different in kind: 9 to 12 inches is a maintained depth, so it has to be raked back and topped up, not just laid once.
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Under two tons covers most patios.
3/8 inch natural pea gravel, priced by the ton, delivered free.
