Pea gravel vs crushed stone
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The comparison is shape plus fines. Maryland’s materials guide says crushed stone has fractured faces that knit, and gravel is the rounded particle that does not. Pea gravel is that rounded particle at about 3/8 inch. #57 is graded from about 1 inch to the No. 4 sieve with almost nothing passing the No. 8. Crusher run keeps the finer sizes the wash plant would have removed. The decision is whether the layer has to pass water, hold a shoe, or hold a tire.
Side by side
| Question | Pea gravel | Clean crushed, such as #57 | Crusher run |
|---|---|---|---|
| Shape | Rounded, about 3/8 inch in the Maryland description. | Fractured faces. Nominal 1 inch to the No. 4 sieve. | Fractured, with the fines left in. Not a size number. |
| Drainage | Open, until soil washes in. The voids stay connected because the pieces are similar. | Open by spec. No. 8 passing is 0 to 5 percent on the M 43 row. | Poor as a drain. The fines are the product. They seal a pipe. |
| Compaction | Seats, then keeps moving. Round pieces do not knit. | Locks at the points, but without fines it does not crust into a bound surface. | Packs. This is the base product. |
| Underfoot | Shifts. Hard on wheels and on anything that has to stay level. | Firmer than pea, still loose on top if it is only one clean size. | Firm once rolled, if it has enough fines and moisture to bind. |
| Typical job | Beds, a loose path, joints, a decorative cover. | French drains, open bases, a clean top over a dense base. | Driveway and shed bases that have to carry load. |
Drainage
Pea gravel drains at the start because the pieces are a similar size. #57 drains under a written limit: on Maryland’s AASHTO M 43 reprint, 0 to 10 percent passes the No. 4 and 0 to 5 percent passes the No. 8. Pea has no such promise, so a load can include sand. Pea also plugs once soil migrates into the voids. Crusher run arrives already full of dust. The French drain calculator uses clean #57 or washed 3/4, and that page calls pea a weak choice beside a foundation because the round stones will not stay in a narrow trench.
The FHWA gravel-roads guide draws the same line for a road. Base gravel there has a larger top size and very little clay. Used as a surface, it will not crust. Surface gravel needs stone, sand, and plastic fines passing the No. 200 sieve, smaller than 0.075 mm. Pea is too uniform to crust and too round to be that stone fraction.
Compaction
Maryland’s guide says the crushed particle knits and the rounded particle does not. The FHWA guide says fractured faces embed and resist movement, and that bank-run rounded gravel is improved by crushing. A plate on pea gravel levels the pile. It does not create that interlock. Crusher run uses both effects: fractured pieces, and fines that fill the gaps. That is why a driveway base is 304, Tennessee Grading D, Class 5, or crusher run, and why those names are not ASTM size numbers. The sizes chart keeps the two lists apart. Quantity for the dense product is the crusher run calculator. The crushed stone calculator is the general angular tool, at the 1,700 kg/m³ planning start.
Clean #57 locks better than pea and still will not crust, because the spec removes the binder. As the only driveway layer it drains and it shoves. As the top inch or two over compacted crusher run it is a surface, not the structure. Depth is the driveway depth guide.
Walkability and where it moves
Pea gravel shifts under a shoe, a stroller wheel, or a chair, and on a slope it migrates downhill. Edging slows that. Fresh angular chips can be sharp and they track indoors, but a dense grade with enough moisture can crust the way the FHWA guide describes: it sheds water until traffic or a blade disturbs it. That is a gravel-road behavior, not a promise that two inches of residential path will act like a county road. It does tell you which product is capable of it.
River rock is larger rounded stone, not crushed stone. The river rock calculator is that decorative layer. It is not a base, and past about 2 inches it is a worse walking surface than pea because you step from rock to rock.
When to choose each
Choose pea gravel for a decorative layer a couple of inches deep, where a little movement is acceptable: beds, a casual path, stepping-stone gaps. Calculate it on the pea gravel calculator, which starts at 1,600 kg/m³. The page’s 1.4 ton figure is 1,660 kg/m³. The density chart says which is which.
Choose clean crushed stone when water is the point. A French drain, an open layer against a wall, and a washed top over a dense base are #57 or washed 3/4, on the #57 calculator or the 3/4 inch calculator. Do not swap in crusher run because it was cheaper. The discount is the fines you decided not to want. Choose crusher run, 304, 411, or Class 5 when the layer has to carry weight: a driveway base, a shed pad, a dense base under pavers. They are not the same gradation. They are the same kind of decision.
A daily path is the middle case. Pea alone ruts. A dense base with a thin pea top looks like pea until the pea scatters. A compacted surface with fines walks better and looks less like a garden. Quantity, after you pick the product, is the matching calculator. This page does not have one.
Do not settle the choice by the tonnage. Pea on this site starts at 1,600 kg/m³, the same clean-stone start as #57. Crushed stone and crusher run start at 1,700. Those are planning defaults on the density chart, and the chart says so. A heavier number does not mean the stone locks, and a lighter number does not mean it drains. Locking is the fractured face and the fines. Draining is the absence of those fines. Read the ticket for the size, then use the calculator only to turn the area and the depth into yards.
Sources
- Maryland Department of the Environment, Guide to Common Construction Materials. Stone versus gravel, pea gravel at about 3/8 inch, and the AASHTO M 43 #57 and #8 rows.
- FHWA Gravel Roads Construction and Maintenance Guide. Surface gravel versus base gravel, crushing, and the No. 200 fines that bind a crust. The same manual is linked from EPA’s gravel-roads page.
- Gravel density chart on this site, for the planning weights. Not a lab report.
Frequently asked questions
Does pea gravel drain better than crushed stone?
Clean pea gravel drains because the pieces are a similar small size and there is almost no dust to plug the voids. Clean crushed stone, such as #57, drains for the same reason: the size band stops at a few percent passing the No. 8 sieve. Crushed stone that still contains fines, sold as crusher run, does not. Compare the product, not the word “crushed.”
Which one is easier to walk on?
Crushed stone with fines, after it is compacted, is the firmer walking surface because the particles lock and the fines fill the gaps. Pea gravel stays loose. The round shape that lets water through also lets the pebbles roll under a shoe, a wheelchair, or a table leg. A path that has to stay put wants the angular product, or a dense base under a thin top.
Can I compact pea gravel into a driveway?
Rolling it will seat it. It will not knit the way angular stone does. The Maryland materials guide describes crushed particles as interlocking and rounded gravel as the particle that does not. The FHWA gravel-roads guide says fractured stone embeds and resists movement, and that bank-run rounded gravel is improved by crushing. A driveway base on this site is crusher run, 304, 411, or Class 5, not pea.
Is pea gravel the same as #8 or #10?
No. #8 is an AASHTO size: 100 percent passing 1/2 inch, 85 to 100 percent passing 3/8 inch, with a controlled band down to the No. 16. It is a crushed chip. #10 screenings, in the Maryland guide, run from about 1/4 inch down to dust. Pea gravel is rounded stone of about 3/8 inch, and it is not a size number. The sizes chart has the sieve rows.
Which stone goes in a French drain?
Clean angular stone. This site’s French drain page uses #57 or washed 3/4 inch and tells you to leave crusher run, 304, and Class 5 out of the pipe envelope because the fines seal it. Pea gravel drains, and that same page calls it a weak choice in a foundation trench because the round pebbles are harder to keep in place. Use the French drain calculator for the stone around the pipe.
Which one should I use around plants?
Pea gravel is the usual mulch-like cover: it stays loose, it does not cut the way a fresh crushed chip can, and you can rake it. It will migrate into soil and onto walks. Crushed stone stays put better and can heat and reflect more, depending on color. Neither one is a soil amendment. If the bed needs drainage under the decorative layer, the open stone is #57, and the pea or river rock is only the visible top.
How do I compare the weight?
Do not compare them from this page. The density chart lists the planning starts: pea gravel at 1,600 kg/m³ with the pea calculator, crushed stone and crusher run at 1,700 kg/m³. Rounded river rock is a separate band, 1,450 to 1,600. Those are the figures already on the calculators. A sieve comparison is not a tonnage.