The Short Answer, Then the Reasoning
Dig about six inches for a standard gravel patio. Four inches of that is compacted angular base stone. The other two inches is the loose gravel you actually walk on. That is the number most people are looking for when they are standing in the yard with a shovel and a flag of marking paint.
One detail changes the whole job if you miss it. Those six inches are measured down from where you want the finished surface to sit, not from the top of the existing grass. Sod, roots, and the loose organic layer under them have to come off first, and that alone can account for an inch or two before you have touched real soil. If you dig six inches below the lawn and then build up, your patio ends up proud of the yard, water runs the wrong way, and the edge is a tripping lip.
The six inch figure holds for a patio carrying foot traffic and normal outdoor furniture on reasonably stable soil. Heavier loads and weaker soils push the base deeper, and we get into exactly how much further down below.
The most useful way to think about any gravel patio is as two separate layers doing two separate jobs. Most of the confusion we hear from homeowners comes from treating the patio as one pile of stone. It is not. One layer is structure and one layer is surface, and they are different products bought on different lines of the same order.
What Each Layer Actually Does
The compacted angular base
The bottom layer is crushed angular stone with fine material mixed in. It goes by different names depending on where you live. Crusher run, CA6, 21AA, Class 5, and ABC are all describing roughly the same idea, a dense grade mix of crushed stone from larger pieces down to stone dust. When you run a plate compactor over it, the sharp edges catch on each other and the fines fill the gaps between them. What you end up with is not a pile of loose rock anymore. It is a firm platform that you can walk across without leaving footprints.
Four inches of compacted base is the reliable standard for a patio seeing regular foot traffic and outdoor furniture. That depth does two things. It spreads the load from a chair leg or a heel out across a wider patch of subgrade instead of concentrating it in one spot, and it gives water somewhere to move downward rather than sitting right under your walking surface.
If you only remember one thing about the base, remember that it has to be compacted in place. Spreading it and raking it flat is not the same as compacting it. A rented plate compactor for an afternoon is the cheapest insurance on the entire project.
The wearing layer on top
The wearing layer is the stone you see and feel underfoot. Pea gravel is the common pick because it is smooth, it is comfortable in bare feet, and it looks finished. About two inches is the sweet spot. Thinner than that and the gray base starts showing through wherever people cut the same corner every day. Thicker and your feet sink in, chair legs wobble and tip, and walking across it feels like loose sand at the beach.
Here is why rounded gravel cannot be the base. Round stones roll past each other under load. There are no sharp edges to interlock and no fines to fill the voids, so they never knit into a stable platform no matter how many passes you make with a compactor. You can run a plate compactor over pea gravel all morning and it will still shift when you step on it. That is fine for a surface layer, where a little give is part of the appeal. It is useless as structure.
Do not skip past the subgrade either. Before any stone goes in, grade the native soil, tamp it, and set your slope so water moves away from the house. A base built over a soft spongy spot will telegraph that soft spot up through both layers within a season. If you hit a patch that feels like a sponge when you step on it, dig it out and replace it with base stone rather than hoping four inches on top will bridge it.
When to Dig Deeper Than Six Inches
Six inches total is the baseline, not a rule. Two things push it deeper, heavy loads and bad soil.
Heavy point loads. A fire pit, a full dining set with six chairs, a stone bench, or a pair of oversized planters put a lot of weight on a small footprint. For those, build the compacted base to five or six inches instead of four. That puts your total excavation at seven or eight inches. You do not necessarily have to do the whole patio that way, but the zone under the heavy item should get the deeper treatment, and it is usually simpler to just go deeper across the whole area than to build a patio with two different base depths.
Soil type. Sandy, well draining soil performs fine at four to six inches of base for pedestrian use. Silty soil is softer and holds more water, so aim for six to eight inches. Clay soil and sites with known drainage problems are the big upgrade. Plan on eight to twelve inches of compacted base there. Clay holds water, swells when it is wet, and shrinks when it dries, and a thin base just rides along with that movement season after season. A deeper base is what keeps the surface flat while the ground underneath is busy moving.
A simple test if you do not know your soil. Dig a hole roughly a foot deep somewhere in the patio footprint, fill it with water, and let it drain completely. Fill it a second time and watch the clock. If the water is gone in a reasonable stretch, you are in decent shape at standard depth. If it is still sitting there hours later, treat the site as poor drainage and add base depth. That test takes an evening and it is more reliable than guessing from the color of the dirt.
Freeze prone climates. The same logic applies. Water that sits trapped under the patio is what causes trouble in winter, because it expands when it freezes and lifts whatever is on top of it. Depth and drainage work together here. A deeper free draining base gives that water a path down and out instead of a place to pool.
Why You Have to Order More Than You Measure
This is the step most homeowners miss, and it is the reason so many gravel patios come up a few inches short on the last day.
Dense grade base material compacts. Crusher run, CA6, 21AA, Class 5, and ABC all lose roughly 20 to 25 percent of their loose depth once you have run a compactor over them. So four inches of finished compacted base does not start as four inches of stone in the pit. It starts as roughly five inches of loose material. If you order for the finished depth, you will be ordering short before you turn the compactor on.
Pea gravel behaves the opposite way. It barely compacts at all, in the range of zero to three percent, and river rock essentially does not compact. For the wearing layer, the quantity you measure is close to the quantity you need.
On top of the compaction math, build in a buffer. Add about 10 percent on a normal flat rectangular project. Go to 15 percent on sloped or irregular sites where you will be feathering depth to hold a grade. Go to 20 percent for a deep, heavily compacted base layer, because the deeper the lift the more the compaction estimate can drift on you.
While we are here, a note on technique that affects your numbers. Spread and tamp the base in lifts of a couple inches rather than dumping the full depth at once and making one pass. A plate compactor transmits its force down only so far. The bottom of a thick single lift stays loose, and an uncompacted bottom layer is exactly where settling starts a year later. Two lifts of two and a half inches, each one compacted properly, beats one five inch dump every time.
Running short mid project is worse than having extra. A second small delivery almost always costs more per yard than the stone itself is worth once you account for the trip. Leftover gravel, on the other hand, has obvious homes. Under downspouts, along a side path, filling the low spot behind the shed, or topping up the patio a year from now when traffic has worn a line through it.
Tonnage Math for a 12 by 14 Patio
Let us run a real one. A 12 foot by 14 foot patio is 168 square feet. The arithmetic is the same every time. Take your depth in inches and divide by 12 to get depth in feet. Multiply square feet by depth in feet, then divide by 27 to get cubic yards. If your patio is a different size or shape, the gravel calculator will run the same math on your own dimensions.
Base layer
We want four inches finished, so we order for five inches loose to cover compaction. That is 168 times 5 divided by 12, which equals 70 cubic feet. Divide by 27 and you get about 2.6 cubic yards.
Crushed stone runs roughly 1.4 to 1.5 tons per cubic yard, so 2.6 yards comes out to roughly 3.6 to 3.9 tons. Round up to about 4 tons and your buffer is already built in.
Pea gravel layer
Two inches finished, and pea gravel does not meaningfully compact, so no adjustment is needed. That is 168 times 2 divided by 12, which equals 28 cubic feet. Divide by 27 and you get about 1.04 cubic yards. Add a small buffer and call it 1.2 cubic yards, or roughly 1.6 tons.
What that looks like on the order form
Two products, two lines. Roughly 4 tons of base stone and roughly 1.6 tons of pea gravel. Run the formula separately for each layer every time. Averaging the two depths together into one number is exactly how people end up with too much of one and not enough of the other, and the one they run short on is almost always the base, because that is the one that compacts. When you are ordering gravel, list them as two distinct items with their own tonnage.
If you are going deeper for a fire pit or because you are building on clay, rerun the base number at the new depth rather than adding a percentage on top of the old one. Going from four inches to six inches of finished base is a 50 percent increase in base material, which is a lot more than the mental buffer most people apply.
Edging, Fabric, and the Mistakes That Undo Good Depth
You can get the depth exactly right and still end up with a patio that disappoints you. These are the details that undo good excavation work.
Edging is not optional. A loose gravel patio has no bond holding it in place. Without a hard edge, the wearing layer migrates out into the lawn a little at a time, every time someone shuffles a chair or runs a mower along the border. The patio gets visibly thinner each season. Homeowners usually blame settling for this, but it is not settling, it is spreading. Steel, aluminum, composite edging, or a stone border all work. What matters is that something stands up at the perimeter and holds the gravel in.
Put the fabric in the right place. Landscape fabric belongs between the subgrade soil and the base stone. Its job there is to keep the soil and the stone from mixing, which is what preserves your base over the years. What it should not do is sit between the base and the pea gravel. A layer of fabric there creates a slick plane, and the top layer slides across it underfoot instead of staying put. If you want fabric, it goes on the dirt, under everything.
Build in slope. Carry a gentle fall away from the house across the finished surface. A perfectly level gravel patio will find low spots you did not plan for and hold water in them. Set the slope at the subgrade stage, keep it through the base, and the wearing layer will follow.
Check the base before the top layer goes on. Compact it, then drag a long straight board across it and look for daylight underneath. Fixing a dip at that point takes a few minutes with a shovel and a rake. Fixing the same dip after two inches of pea gravel is on top means raking the whole surface layer off to one side and putting it back.
Do not skip the base. Laying pea gravel straight on dirt is the most common shortcut and the one with the shortest shelf life. The stone presses down into the soil under foot traffic, soil works up between the stones from below, and within a season you have a patio that is half gravel and half mud. There is no amount of extra pea gravel that fixes that, because the problem is underneath it.
How We Started
We started Mulch Mound because we got tired of the hassle that came with buying landscaping materials. The options were either loading bags into your car at a garden center or calling around to local suppliers, trying to figure out pricing, minimums, and delivery schedules. Neither option felt convenient or transparent.
Three of us – Alec, Mo, and Tyler – decided there had to be a better way. Alec and Tyler got their start back in 2013 running a landscaping business during college, moving mulch and mowing lawns to pay tuition. That experience taught them how frustrating it was to source materials, and years later, that frustration turned into Mulch Mound.
We focus on making it simple to get mulch, stone, and soil delivered directly to your home. Order online, pick your delivery date, and we handle the rest. No loading bags. No calling multiple suppliers. No wondering if you bought enough or paid a fair price.
We work with quality local suppliers in the areas we serve and aim to be straightforward about what we offer and what it costs. Landscaping is hard work. Buying the materials for it shouldn't be.
Frequently asked questions
How deep should pea gravel be for a patio?
Two inches on the walking surface. A garden path or a decorative bed can go a little thinner, around an inch and a half, because nobody is setting a chair down on it and the stone is not taking the same concentrated pressure. A parking pad or a driveway is a different build entirely and should not be approached as a deeper version of a patio.
Can I put pea gravel directly on soil?
Only for a low stakes path you would not mind rebuilding. Beyond the stone sinking into the dirt, the weed problem surprises people. Grass and weeds come up through unsupported gravel much faster than expected, because a loose layer of round stone lets plenty of light through to the soil. A compacted base with fabric under it blocks light and gives roots nothing easy to work with, which is most of the reason a properly built gravel patio stays clean looking with far less pulling.
How much does gravel compact after tamping?
Dense grade base loses roughly a fifth to a quarter of its loose depth. There is an easy field check. Push a stake into the subgrade and mark it at your loose spread depth before you start. As you make passes with the compactor, watch how far the stone drops below that mark. When it stops dropping between passes, that lift is done and you can measure what you actually have before spreading the next one.
What should I excavate for a fire pit on a gravel patio?
Treat the fire pit footprint as its own small project inside the larger one. It carries concentrated weight, so it wants a deeper compacted base underneath it than the surrounding patio. It also wants a non combustible surface directly under and around the ring rather than loose pea gravel, so plan on pavers, flagstone, or a stone apron in that zone and let the pea gravel pick up at the edge of it.
Does the base depth change if I use flagstone or pavers instead of loose gravel?
The compacted base stays in the same range. What changes is the top of the stack, because a bedding layer enters the build between the base and the stone, and the thickness of the pavers or flagstone themselves has to be counted in your excavation. So the structure underneath is familiar, but you have to measure down from the finished surface with the whole stack in mind rather than just adding two inches of gravel on top of a four inch base.