Pea Gravel Calculator

Pea gravel, also sold as pea stone or pea shingle, is a rounded 3/8 inch (10 mm) aggregate. To work out how much you need, multiply the area you are covering by the depth you want, then convert to the units your supplier sells in. In square feet and inches that is:

For most people the quickest answer is that one cubic yard covers 162 square feet at 2 inches deep, and weighs about 1.35 US tons. If you would rather not do any of this by hand, the calculator above has it covered.

Driveways need a base, not just more gravel

Pea gravel is rounded and water-worn, so the stones roll over each other instead of locking together the way crushed stone does. Poured straight onto soil it will rut under tyres within a season. Build 4–6 inches of compacted crushed stone first, then 2–3 inches of pea gravel on top, and edge it firmly.

Playground depths are a safety standard, not a preference

The US Consumer Product Safety Commission treats pea gravel as an acceptable playground surfacing material, but only at depth around 9 inches uncompressed for equipment with a fall height up to about 5 feet, and more for taller equipment. This is one case where you should follow the published guidance rather than the look you want.

CPSC guidance sets loose-fill depth by equipment fall height, and accounts for compaction: an initial fill of about 12 inches settles to roughly the 9 inches of maintained depth the guidance calls for.

French drains are measured by trench, not by area

For a drain you are filling a trench, so switch the calculator to Volume mode, or use Rectangle mode with the trench length and width and the fill depth. A 50 ft trench 12 in wide filled 18 in deep needs 75 cubic feet about 2.8 cubic yards.

Why calculators disagree on weight

Volume is arithmetic and every calculator agrees on it. Weight is an assumption. Each tool picks a density for pea gravel and rarely tells you which one, and the published figures differ by nearly 12% from end to end:

On a 3 cubic yard order that spread is the difference between 3.6 and 4.3 tons most of a half-yard. Three things drive it:

• Stone type. Pea gravel is whatever rounded stone the local pit produces. Granite, limestone and basalt have genuinely different specific gravities.
• Moisture. Quarries quote dry weight. Gravel that has sat through rain carries roughly 8% more, and can run higher still.
• Settlement. A freshly tipped load holds more air than one that has been sitting in a bay for a month.

This calculator uses 100 lb/ft³ 1.35 US tons per cubic yard the mid-range figure for rounded, water-worn gravel in the 3/8 inch size class, and adds 8% when you switch it to wet. That is a defensible middle, not a universal truth.

Bagged pea gravel runs roughly $4–$8 per half-cubic-foot bag. At 54 bags to the cubic yard that is around $270 per cubic yard. Bulk delivered runs $30–$65 per ton about $67 per cubic yard at $50/ton plus a delivery fee of $50–$100 and often a minimum load.

Bulk is roughly four times cheaper per yard, so the only question is whether your job is big enough to absorb the delivery fee. With a $75 fee the crossover lands at about 0.4 cubic yards near enough 60 square feet at 2 inches deep.

The price comparison hides one thing. 54 bags per cubic yard is a genuinely unpleasant afternoon. At 50 lb each that is 2,700 lb lifted twice once into the car, once out. Past a yard, pay the delivery fee for your back rather than your wallet.

At 2,700 lb per cubic yard, a single yard exceeds the payload of nearly every half-ton pickup on the road. Yards will happily load what you ask for, and the overload is yours to drive home.

Most calculators only take a length and a width, which leaves you doing the geometry yourself. This one has a mode for each case:

Circles

Measure straight across the widest point to get the diameter and use Circle mode. The area is π × radius², so a 10 ft circle is 78.5 ft² not 100 ft². Using the diameter as if it were a square over-orders by about 27%.

L-shapes

Split the L into two rectangles that do not overlap, measure each, and use L-shape mode. The common mistake is measuring the bounding box of the whole thing, which counts the missing corner as gravel.

Curved and irregular beds

Break the shape into rectangles, triangles and half-circles, work out each piece, and add them. For a genuinely freeform bed, lay a hose along the outline and box it into rough rectangles then use Area mode with the total. Being 5% out on an irregular bed is well inside the waste allowance.

Trenches and known volumes

If you already know the volume a supplier quote, a trench spec, a previous order use Volume mode. It skips depth entirely and converts straight to weight, bags and cost.

Add the base layer to your order if you need one it is usually a bigger volume than the gravel itself. A 12 × 24 ft driveway needs about 4.4 cubic yards of pea gravel at 4 inches, and roughly 7 cubic yards of crushed stone underneath at 6 inches.

The short version is simple. If it needs to stay put under weight, you want angular stone. Pea gravel wins on comfort underfoot, drainage and price, and loses on stability. Decomposed granite is the usual answer when you want a natural-looking path that a stroller can cross.