Pea Shingle Calculator
Estimate pea shingle or pea gravel by shape, depth, drainage bedding, density, moisture, compaction, edging loss, bags, tons, and cubic yards.
⚫Quick pea gravel presets
📏Calculator inputs
🧱Aggregate grid
📊Pea shingle density presets
| Preset | Typical size | Density | Best use |
|---|---|---|---|
| 6 mm silver pea shingle | Fine 6 mm | 1.24 tons/yd³ | Decorative beds and thin bands |
| 10 mm buff pea gravel | Rounded 10 mm | 1.28 tons/yd³ | General paths and patios |
| 12 mm honey pea shingle | Rounded 12 mm | 1.31 tons/yd³ | Courtyard infill and edging |
| 14 mm river pea gravel | Smooth 14 mm | 1.26 tons/yd³ | Fire pit rings and seating zones |
| 20 mm washed flint | Open 20 mm | 1.34 tons/yd³ | Drainage trenches and splash strips |
📐Shape formulas and measuring guide
| Shape mode | Area formula | Depth formula | When to use |
|---|---|---|---|
| Rectangle or strip | Length × width | Area × depth | Paths, patios, aprons, rectangular beds |
| Circle or round bed | 3.1416 × radius² | Area × depth | Tree rings, fire pit circles, round features |
| Trench or drain | Length × width | Run volume plus bedding | French drains, pipe cover, downspout channels |
| Bedding layer | Same footprint | Area × bedding depth | Extra drainage layer under finished pea gravel |
📦Bag and bulk conversion table
| Quantity | Imperial conversion | Metric conversion | Use in calculator |
|---|---|---|---|
| Volume | 1 yd³ = 27 ft³ | 1 m³ = 1.308 yd³ | Result card one |
| Weight | 1 ton = 2,000 lb | 1 tonne = 1,000 kg | Density and bag math |
| Bags | 40, 50, or 80 lb | 20 or 25 kg | Rounded up to whole bags |
| Loads | Tons per truck load | Tonnes per delivery load | Rounded up to whole loads |
📋Recommended depths by pea gravel use
| Project | Finished depth | Allowance | Note |
|---|---|---|---|
| Decorative bed cover | 1.5-2 in | 5-8% | Use edging to reduce spill |
| Walking path | 2-3 in | 8-12% | Compact lightly after spreading |
| Patio or seating area | 2.5-3.5 in | 10-12% | Use fabric beneath loose shingle |
| Drainage trench | 4-8 in | 12-16% | Choose open washed stone |
If you’ve ever bought pea gravel (also called pea shingle) to put down on a driveway or in a border in the garden, you know how hard it can be to order up enough. Because when you buy the stuff, it all looks the same, uniform… And so you think: Easy math. But volume never are easy. A cubic yard is a big box of rocks.
By eyeballing how much space that might take up and guessing that’s about three boxes, you are gambling…and gambling with dollars. The calculator above will do the math for you. It’ll translate your measurements into meaningful amounts like bulk loads, tons, or bags. Knowing what those mean is every bit as key as getting them.
How to Measure Your Gravel Needs
First, there is a difference between volume and depth. Depth is one dimension and volume is three dimensions, but how do we humans think about it? We think in terms of layers. I see a layer of 2 inches of nice smooth round stones. That sounds like a neat little package around a foundation or feels good to walk on.
But guess what; that layer exist on top of footprint. And footprints are shaped. And footprints are shaped. If the footprint was a straight line it would be an easy measurement. You would need a different kind of geometry for a curving trench or a circular fire pit ring. This is where the tool come into play. You give it your measurements and it figures out the right surface area to apply.
That’s where people mess up. They take a measurement of the length of something but not its width when they convert to cubic units. The mistake gets fixed automaticly by the calculator.
And then there’s bedding. That’s another layer in and of itself. For long-lasting installations, decorative stone is not just threw randomly on the ground. The first thing they do is lay down a deeper, finer aggregate that lets water flow through. This is called the drainage layer. Typically a proper trench require four-to-eight inches of depth, depending on how much water flows across the area. But this doesn’t have to be pretty; it just has to be deep enough to function properly.
Your total depth is made by combining this deeper, less attractive layer (the ugliest part) with the shallow, pretty stuff on top (the face). Ignore or mix up the input for bedding depth and your path will turn to mush in a season. The bedding depth input is there so you buy sufficient rough stone for underneath, not just the front.
Hidden variables also include density. All stone doesn’t weigh the same. A cubic yard of lightweight limestone and a cubic yard of heavy granite may take up the same amount of space, but will feel quite different. To translate that volume into pounds, the calculator has pre-programmed densities of different kinds of stones, washed flint, silver pea shingle and so forth. That’s important, since suppliers charge by the ton, not the yard.
Order by volume alone, and you run the risk of short-changing yourself in terms of weight. You’ll end up with less stone than you need to cover the area. This will lead to an awkward conversation with the delivery driver as he backs the truck away while still carrying half a ton. It’s one of those little details that keeps the awkward conversation from happening.
The last wild cards is moisture and compaction. Yes, stone does settle. When you rake it out, it looks fluffy, but once you walk on it, it compress. Then it gets compacted down. The calculator also factors in some settling percentage (typically five- to twelve-percent), depending upon the amount of traffic it will receive. Throw in a bit more for edge spills, and there you go! It is a safety net. It is not waste, but insurance against what will inevitably happen when the stone settles in and creates bare patches where gaps between stones can occur. Better a couple extra bags in the corner than a gaping hole in the center of your path.
The bottom line: There’s not much precision in estimating gravel; just lots of variables. “You might have a perfect rectangle but then you’ve got this piece of ground that isn’t flat and the gravel moves around.” The tool is a starting point… Based off the math of the geometry plus the physics of the material, and from there you rely on your eyeballs to adjust for what’s really happening on the ground. If you’re lining a driveway or filling in a small garden bed, you’ll want the same thing: the stone to blend in as though it were always there. To do that, you should of buy enough to fill in all the gaps.
