Stone Calculator: Ordering Washed Stone by Its Number
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Most orders that start here are drainage, and drainage in Missouri gets dug on a narrow calendar. Heavy spring storms send water down the hollows and across the flat northern ground faster than the subsoil will take it, which is when the wet corner announces itself; the trench then waits for ground dry enough to open, and the work lands between late spring and the first hard freeze. Whatever the season, the number you type into the stone calculator is a grade number, and that is what separates this page from the one next door.
When the Job Names a Number and When It Names a Drive
This page is for graded crushed stone bought by its size: the washed rock a plan, a septic layout or a permit calls out by number, plus screenings and ballast at either end of the range. Twelve products, from three-eighths inch chips up to two-and-a-half inch ballast, each figured at its own weight.
The gravel calculator is for the other question, where nobody has named a grade and the job is a surface: a drive to be topped, a path, a play area, an odd-shaped pad that needs measuring before anything else. If the layer is meant to compact and carry a load rather than drain, you want base rock on the road base calculator or the crusher run calculator instead.
Reading the Grade Before You Open the Material List
Lower numbers mean bigger stone. In Missouri names, one inch clean is #57 at 3/16 to 1 inch, and it does most of the drainage, driveway and concrete work in the state. #67 runs finer at a quarter to three-quarters and often goes under pipe. #4 is the coarse one at 3/4 to 1-1/2 inches, sold locally as two inch clean, for construction entrances and trench bottoms. #8 is about 3/32 to 3/8 inch and #89 runs from three-eighths down into fines, both of them joint and finish material, sold as chips. Screenings are crushed dust and small chips that compact into a firm bed. Railroad ballast is heavy angular rock from one to two and a half inches.
Clean rock means one thing here and it is worth being exact about it: washed stone with no fines at all. It stays open so water can move through it. Base rock and crusher run carry fines by design, which is why they lock up under a drive and why they will silt a French drain shut. If a plan names a gradation, follow the plan; if a supplier ticket and a drawing use different words for what looks like the same stone, ask before ordering rather than after.
Measuring a Trench, a Ring Bed and an Entrance
Trenches are length by width, taken at the width you actually dug rather than the width you marked, which on chert and rock is usually wider. An entrance or a pad is length by width. A ring around a well head or a downspout is the outer circle less the inner one. On a slope, run the tape on the ground.
Do not deduct the pipe. A four-inch line down the middle of a trench displaces about a tenth of a yard over thirty feet, which is less than a wheelbarrow, and the stone has to go round it as well as under it.
Twelve Grades and a Depth Field That Stops at 24 Inches
Rectangle, circle, or up to five separate areas totaled together. Length, width and diameter in feet, depth in inches from 0.25 to 24. Choose the grade from the material list so the right weight gets applied, leave the optional five percent for compaction and spillage ticked if you want it, and calculate for cubic yards, tons and cubic feet. There is an email field if you want the figures sent to you.
The 24-inch ceiling matters on this page more than on any other, because trench backfill and wall drainage routinely run deeper than two feet. Enter a 30-inch trench as a 24-inch pass plus a 6-inch pass over the same footprint and add the two results.
Why the Same Trench Weighs Differently by Grade
Cubic yards are the area in square feet times the depth in inches divided by 12, all divided by 27. Tons are those yards times the weight of the grade you picked.
| Grade | Approximate pounds per yard | Tons per yard |
|---|---|---|
| #57, #67 or 3/4 inch crushed stone | 2,800 | 1.40 |
| #89, #8 or 3/8 inch chips | 2,800 | 1.40 |
| Stone screenings | 2,900 | 1.45 |
| #4 stone or railroad ballast | 2,900 | 1.45 |
| Crusher run or road base | 3,000 | 1.50 |
| Rip rap | 3,100 | 1.55 |
Take 200 square feet at four inches, which is 2.47 cubic yards whatever goes in it. As one inch clean that is 3.5 tons; as screenings 3.6; as rip rap 3.8. A ton of one inch clean covers roughly 116 square feet at two inches, 77 at three and 58 at four.
A French Drain, a Septic Line and a Construction Entrance
Hypothetical sizes, not customer jobs.
A French drain on a wet Ozark hillside, 45 feet long, 12 inches wide, filled 14 inches with one inch clean.
- 45 sq ft x 14 / 12 = 52.5 cu ft
- 52.5 / 27 = 1.94 cu yd, or 2.7 tons at 1.40
Bedding under a 60-foot line, 2 feet wide at six inches of three-quarter inch clean.
- 120 sq ft x 6 / 12 = 60 cu ft
- 60 / 27 = 2.22 cu yd, or 3.1 tons
A construction entrance off a gravel county road, 50 by 14 feet at six inches of #4.
- 700 sq ft x 6 / 12 = 350 cu ft
- 350 / 27 = 12.96 cu yd, or 18.8 tons at 1.45
Line a drain trench with non-woven fabric before the stone goes in, or the soil around it will fill the voids that make it work. Where the ground is karst and a sinkhole or a losing stream is nearby, take advice on where the outfall goes before you dig.
Five Percent Covers Spillage, Not a Trench Dug Wide
The tick box is a small allowance for what falls off the wheelbarrow and settles under traffic. It does not cover a trench that opened up two inches wider than planned in rocky ground, and it does not cover an engineered base, which is ordered to its specified compacted depth. Angular clean stone settles by something like five to ten percent under traffic; material with fines in it compacts a good deal more, on purpose.
Order 1 inch clean or 3/4 inch clean for open drainage, screenings where a firm screeded bed is wanted, and railroad ballast for hard standing. Set the quantity and a date on the product page. Delivery is arranged at checkout by ZIP code and the truck needs clear access to a dump spot, so give a trench job a drop point that is not the far end of a soft lawn.
Common questions
Can I check the tonnage on paper before I order?
Yes, and it is worth doing once. A ton of one inch clean is about 0.71 cubic yards, which is 19.3 cubic feet. Divide that by the depth in feet and you get the square footage a ton covers: at three inches, 77 square feet. Compare it against what the tool gives you for the same area.
Why did the tons jump when I switched from one inch clean to screenings?
Because the volume stayed the same and the weight changed. Clean stone at 2,800 pounds a yard is 1.40 tons; screenings at 2,900 are 1.45, and crusher run at 3,000 is 1.50. Over a 5-yard job that is a quarter of a ton of difference for the identical hole.
Is the five percent enough for stone I am going to compact?
For a drainage trench, yes, since clean stone barely moves. For anything being rolled, order to the compacted depth you want and treat the tick box as spillage cover. A base built to a specification is sized by that specification, not by an allowance.
The drainage line runs down a bank. How do I measure the length?
Along the ground, tape lying on the slope, because that is how far the trench actually runs. Measuring the flat distance on a steep Ozark pull will leave you short, and the deep end at the bottom usually wants its own entry with a greater depth anyway.
The stone bed wraps around two sides of the shed. Can I do it in one run?
Yes. Multiple areas takes up to five rectangles and adds them. Split at the corner so the legs do not overlap: 20 by 8 feet plus 12 by 6 feet at three inches is 232 square feet, 58 cubic feet, 2.15 cubic yards and about 3.0 tons of one inch clean.
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Twelve graded stone products, priced per ton, free delivery across Missouri.
