#6 Stone: Size, Uses, Weight and How Many Tons

#6 stone is a clean crushed stone sized from about 3/4 inch down to 3/8 inch, with very little dust or small chips mixed in. Every piece falls inside a fairly narrow band, so the stone drains well, looks uniform and does not pack into a hard surface. It is less common than #57 or #67, but many quarries in the eastern and central United States make it, and you will see it called for in concrete mixes, drainage work, pipe bedding and decorative stone jobs. A loose cubic yard weighs roughly 1.35 to 1.5 tons. This guide covers the official size limits, how #6 compares with the stones next to it on the chart, where it works well, and how many tons to order.

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What “#6” means on the stone size chart

Stone numbers come from ASTM D448, the standard sizing chart for coarse aggregate. AASHTO M 43, which state highway departments lean on, uses the same numbers. Size No. 6 has a nominal range of 3/4 inch (19 mm) down to 3/8 inch (9.5 mm). The standard caps how much of a sample, by weight, may pass each screen:

Screen opening	Share passing, by weight (size No. 6)
1 inch	100%
3/4 inch	90 to 100%
1/2 inch	20 to 55%
3/8 inch	0 to 15%
No. 4 (about 3/16 inch)	0 to 5%

In plain terms: all of it fits through a 1-inch screen, nearly all of it fits through 3/4 inch, about half or more is held up by a 1/2-inch screen, and almost nothing is small enough to drop through 3/8 inch. That missing bottom end is the main thing that sets #6 apart from #57 and #67, which both run down to about 3/16 inch.

Because #6 is not stocked everywhere, a local yard may sell something close under another name, such as “3/4-inch clean,” “3/4-inch washed” or a state DOT size number. If a drawing or spec calls for size No. 6, ask for the yard's gradation sheet and compare it with the table above.

#6 stone vs #5, #57, #67 and #8

On the ASTM chart, larger single numbers mean smaller stone, and two-digit numbers such as 57 and 67 combine two neighboring sizes into one broader blend.

Size	Nominal range	Fines?	Typical uses
#5	1 in to 1/2 in	Very little	Drainage, concrete, base under slabs
#57	1 in to 3/16 in	Very little	Drainage, concrete, driveway topping
#6	3/4 in to 3/8 in	Very little	Concrete, drainage, pipe bedding, decorative stone
#67	3/4 in to 3/16 in	Very little	Concrete, drainage, pipe bedding
#8	3/8 in to about 3/32 in	Very little	Chip seal, paver bedding, pipe bedding

#6 vs #67. Both top out at 3/4 inch. #67 keeps going down to about 3/16 inch, so it has more small pieces filling the gaps. #6 stops at 3/8 inch, so it has larger open spaces between stones, drains a little faster and looks more even. Think of #67 as #6 with a share of smaller chips mixed in.

#6 vs #57. #57 runs from 1 inch to about 3/16 inch, a wider spread on both ends. It is the most widely stocked clean stone, so it is often cheaper and easier to find. #6 is a little smaller on top and has no small chips on the bottom.

#6 vs #5. #5 is the next size up, running from 1 inch to 1/2 inch. Blend #5 with #6 and you get roughly the #56 size on the chart. Pick #5 when you want bulkier stone and #6 when you want a slightly finer, still very open stone.

#6 vs #8. #8 begins about where #6 ends. It is the go-to small chip for paver bedding and chip seal, while #6 is better when you need more bulk and more void space.

Common uses for #6 stone

Concrete aggregate. A clean, uniform 3/4-inch stone works as coarse aggregate in many concrete mixes. The ready-mix plant or engineer sets the mix design, so do not swap sizes on a structural pour without asking.
Drainage layers. With no fines to clog the gaps, #6 moves water well behind retaining walls, around foundation drains and under patios. Our foundation drainage gravel guide explains where clean stone helps.
French drains and dry wells. #6 is a reasonable fill around perforated pipe when it is wrapped in filter fabric. See the French drain gravel guide for how it compares with #57.
Pipe bedding. Uniform clean stone settles evenly around pipe. Plumbing codes, utility specs and pipe makers set the bedding requirements.
Walkways and decorative beds. Pieces around 1/2 to 3/4 inch look tidy in landscape beds and on paths that see light foot traffic. Edging keeps the stone from wandering.
Driveway topping. A thin layer over a compacted base gives a clean, rough surface. On its own it will shift under tires, so it should not be the whole driveway.

When to pick something else

Driveway or slab base. A base needs fines that bind the stone together. Dense-graded material such as crusher run compacts into a firm layer; clean #6 does not. Use clean stone only as a top layer or where drainage matters more than stiffness.
Paver setting bed. Most paver makers call for concrete sand or a small chip such as #8 or #9 for the bedding layer. #6 is too coarse to screed smooth.
Steep grades. Clean stone rolls downhill. A binder, larger angular stone or a different surface holds better on slopes.
Where you can only get #57. For most drainage jobs #57 works just as well. Do not pay extra or wait weeks for #6 unless a spec calls for it.

How much a yard of #6 stone weighs

A uniform clean stone holds more air between the pieces than a dense base, so it weighs a bit less per yard. Limestone, granite and trap rock in the #6 size usually weigh about 1.35 to 1.5 tons per loose cubic yard, roughly 2,700 to 3,000 pounds. The math below uses 1.4 tons per yard. Dense rock types and wet stone weigh more. Our crushed stone weight chart covers other materials.

How deep to lay #6 stone

Landscape beds: about 2 to 3 inches over fabric hides the soil and holds up to raking.
Garden paths: about 3 inches, ideally over a compacted base on soft ground.
Drainage layer behind a wall or under a patio: often 4 to 12 inches, set by the wall maker's guide or the plans.
Driveway topping: about 2 inches over a compacted base.

These are planning numbers. Product instructions, a permit or an engineer's drawing always come first.

How many tons of #6 stone to order

Measure the length and width in feet and the depth in inches, then:

Cubic yards = length × width × depth in inches ÷ 324
Tons ≈ cubic yards × 1.4
Square feet covered per ton ≈ 230 ÷ depth in inches

Add 5 to 10 percent for uneven ground and stone that sinks into soft soil.

Depth	Approx. area per ton	Tons per 100 sq ft
2 inches	about 115 sq ft	about 0.86
3 inches	about 77 sq ft	about 1.3
4 inches	about 58 sq ft	about 1.7
6 inches	about 38 sq ft	about 2.6

Example: a landscape bed 6 feet by 30 feet, 3 inches deep. 6 × 30 × 3 ÷ 324 = about 1.7 cubic yards. 1.7 × 1.4 = about 2.3 tons. With 10 percent extra, order about 2.5 tons.

Example: a drainage layer 2 feet wide and 40 feet long behind a wall, 12 inches deep. 2 × 40 × 12 ÷ 324 = about 3 cubic yards. 3 × 1.4 = about 4.2 tons, so plan on about 4.5 tons with extra.

The crushed stone coverage guide and the base calculator handle other shapes and depths.

Buying tips

Call before you count on it. Not every yard makes #6. Ask for it by number and as “3/4-inch clean,” and ask for the gradation if the size matters.
Ask about the rock type. Limestone, granite, trap rock and river gravel differ in color, weight and how sharp the edges are.
Know the delivery minimum. Many yards set a minimum load or charge a short-load fee. Small jobs may be cheaper to haul yourself if your truck or trailer can carry the weight.
Plan the drop spot. Have the load dumped close to the work on a tarp or hard surface, clear of septic lines, soft lawn and overhead wires.

Questions people ask

What size is #6 stone?

ASTM size No. 6 runs from 3/4 inch down to 3/8 inch. All of it passes a 1-inch screen, 90 to 100 percent passes 3/4 inch, 20 to 55 percent passes 1/2 inch, and no more than 15 percent passes 3/8 inch.

What is #6 stone used for?

Common uses include coarse aggregate for concrete, drainage layers behind walls and around foundation drains, French drains, pipe bedding, landscape beds, light-traffic paths and a thin topping over a compacted driveway base.

What is the difference between #6 and #67 stone?

Both top out at 3/4 inch, but #67 continues down to about 3/16 inch while #6 stops at 3/8 inch. #6 has larger open spaces between stones and looks more uniform; #67 has more small pieces.

How much does a yard of #6 stone weigh?

About 1.35 to 1.5 tons per loose cubic yard, roughly 2,700 to 3,000 pounds, depending on the rock type and moisture. Use 1.4 tons per yard for planning.

Does #6 stone compact?

Very little. It is a clean stone with almost no fines, so it settles and nests a bit when tamped but does not form a hard, stable layer the way crusher run does.

How many square feet does a ton of #6 stone cover?

About 115 square feet at 2 inches deep, 77 square feet at 3 inches and 58 square feet at 4 inches. Add 5 to 10 percent for uneven ground.

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