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

#78 stone is a crushed aggregate from the ASTM size chart that lands between #67 and #8. A typical load runs from about 1/2 inch down to roughly 3/32 inch, so it is a small, angular chip with a few pea-sized pieces mixed in and very little dust. You will see it called for in concrete and asphalt mixes, as pipe and paver bedding on some jobs, in walkways, and as a clean top dressing over a firmer base. For planning, a cubic yard usually weighs about 1.35 to 1.5 tons. This guide covers what the number means, how #78 compares with the sizes around it, where it works and where it does not, and how to figure the tons to order.

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What the “78” in #78 stone means

The number is a size designation from ASTM D448, the same table that defines #57, #67, #8 and #9 (AASHTO M 43 is the matching highway standard). Two-digit sizes are blends: #78 covers the band from the top of size #7 to the bottom of size #8. Its nominal range is 1/2 inch (12.5 mm) down to the No. 8 sieve (2.36 mm). The standard limits how much of the stone, by weight, may pass each screen:

Screen opening	Share passing, by weight (size No. 78)
3/4 inch	100%
1/2 inch	90 to 100%
3/8 inch	40 to 75%
No. 4 (about 3/16 in)	5 to 25%
No. 8 (about 3/32 in)	0 to 10%
No. 16 (about 1/20 in)	0 to 5%

In plain terms: nothing is larger than 3/4 inch, nearly all of it fits through a 1/2-inch screen, somewhere around half is bigger than 3/8 inch, and only a small share is fine grit. That makes #78 a little coarser than #8 and noticeably smaller than #67 or #57.

Local names vary. A yard may sell it as “78s,” “1/2-inch chip,” “#78 gravel” or just “small crushed stone.” When a plan, a paver system or a state spec names size No. 78, ask for the current gradation sheet so you know the pile actually matches.

#78 stone vs #57, #67, #8 and #89

On the ASTM chart, bigger numbers mean smaller stone. Here is where #78 sits among the sizes people usually compare it with:

Size	Nominal range	Where it usually goes
#57	1 in to No. 4	Drainage layers, concrete, driveway surfaces
#67	3/4 in to No. 4	Concrete, slab and pipe bedding
#78	1/2 in to No. 8	Smaller-aggregate concrete and asphalt mixes, bedding, walkways, top dressing
#8	3/8 in to No. 8	Permeable paver bedding and joints, exposed aggregate
#89	3/8 in to No. 16	Narrow paver joints, fine mixes, thin lifts

#78 vs #57. This is the comparison people search most. #57 tops out at 1 inch and has much bigger gaps between stones, so it carries more water and makes a better drainage layer. #78 is smaller and smoother underfoot, packs into a tighter surface and fits thinner concrete sections. If the job is a French drain or a drainage blanket, #57 is the usual pick; if the job is a walkway topping or a mix with tight clearances, #78 often makes more sense.

#78 vs #67. #67 runs up to 3/4 inch, so it is the next size up. Both see use in concrete; #78 is chosen when the mix has to pass through tighter rebar or fill a thinner pour.

#78 vs #8. These overlap heavily at the small end. #78 keeps more pieces between 3/8 and 1/2 inch, so it is a touch chunkier and a bit more stable as a surface; #8 is the more common choice for permeable paver bedding.

Where #78 stone works well

Concrete and masonry. Smaller coarse aggregate helps a mix flow around closely spaced steel and fill thin slabs, toppings and block cores. The mix designer or ready-mix plant chooses the size, and #78 is one of the regular options.
Asphalt mixes. Many plants use stone in this band for surface and intermediate mixes. The highway agency or the plant’s mix design sets the exact grade, so do not assume the nickname on a stockpile matches a paving spec.
Pipe and utility bedding. Some specs allow small clean crushed stone around pipes because it settles into place with little effort. Follow the pipe maker’s or the engineer’s bedding detail; some call for #57 or #67 instead.
Walkways and patios. Angular #78 locks together better than rounded pea gravel of a similar size, so it stays put on garden paths. Our gravel walkway guide covers edging and base layers.
Top dressing a stone driveway. A thin layer over a compacted dense-graded base gives a cleaner look. Keep it thin; see the next section for why.

Where it is the wrong choice

On its own, a thick layer of #78 makes a weak driveway base. It has almost no fines to bind it, so a deep blanket of small chips shifts and ruts under tires. Build the base with a dense-graded product such as crusher run and use #78 only as a thin wearing course if you want the look. Our chart of driveway gravel sizes by layer shows a typical build. For serious drainage, such as a French drain or a gravel trench, larger clean stone moves far more water; see our French drain gravel guide.

How much a yard of #78 stone weighs

Crushed limestone or granite in this size usually weighs about 1.35 to 1.5 tons per loose cubic yard, or roughly 2,700 to 3,000 pounds. A planning number of 1.4 tons per yard works for most orders unless the quarry publishes its own figure. Denser rock such as trap rock, and stone that is wet from washing, will weigh more on the scale ticket. Compare other products in our crushed stone weight chart.

How deep to place #78 stone

Walkway or path surface: about 2 to 3 inches over a firm, compacted base.
Top dressing on a stone driveway: about 1 to 2 inches over a compacted dense-graded base.
Pipe bedding: the depth on the bedding detail, often a few inches under the pipe and up the sides.
Mixes: metered by weight at the plant, so there is no field depth to plan.

Treat these as starting points. A plan sheet, a manufacturer’s chart or a permit detail always wins.

How many tons of #78 stone to order

Measure the area in square feet and the depth in inches, then:

Cubic yards = square feet × depth in inches ÷ 324
Tons ≈ cubic yards × 1.4 (about square feet × inches × 0.0043)
Square feet one ton covers ≈ 230 ÷ depth in inches

Add about 10 percent for settling, uneven ground and spillage.

Depth	Approx. area per ton	Tons per 100 sq ft
1 inch	about 230 sq ft	about 0.4
2 inches	about 115 sq ft	about 0.9
3 inches	about 77 sq ft	about 1.3
4 inches	about 58 sq ft	about 1.7

Example: a walkway 4 feet wide and 50 feet long, 3 inches deep. 4 × 50 = 200 square feet. 200 × 3 ÷ 324 = about 1.85 cubic yards. 1.85 × 1.4 = about 2.6 tons. With 10 percent added, order about 2.9 tons, or 3 tons if the yard sells whole tons.

Example: a 1.5-inch top dressing on a 12 by 80 foot driveway. 960 square feet × 1.5 ÷ 324 = about 4.4 cubic yards, or about 6.2 tons. Order about 7 tons. If you are picking it up yourself, our guide to tons of gravel in a dump truck helps you match the order to your truck or trailer.

Tips for spreading it

Compact the soil or base first. Small stone over soft ground simply sinks.
Use edging on paths and beds so the chips do not migrate into the lawn.
Spread with a rake in thin passes and check depth with a marked stake.
Run a plate compactor over walkway layers to seat the stone.
Keep mulch, clay and topsoil off the pile. Dirty stone stops draining and grows weeds sooner.

Buying tips

Name the size, not the nickname. Ask for ASTM D448 size No. 78 when it matters, and request the gradation sheet.
Ask whether it is washed. Washed stone has less dust, looks cleaner and drains better.
Check the rock type. Limestone, granite and trap rock differ in color, weight and price, and some state specs limit which you can use.
Watch delivery minimums. A small walkway may need only two or three tons. Pairing the order with base stone can avoid a short-load fee.

Questions people ask

What size is #78 stone?

ASTM size No. 78 runs from 1/2 inch down to the No. 8 sieve, about 3/32 inch. All of it passes a 3/4-inch screen, 90 to 100 percent passes 1/2 inch, and very little is fine grit.

What is the difference between #78 and #57 stone?

#57 tops out at 1 inch and has larger gaps between stones, so it drains better. #78 is smaller, packs into a tighter surface and fits thinner concrete sections and walkways.

Is #78 stone the same as #8 stone?

No, but they overlap. Both bottom out near the No. 8 sieve, while #78 keeps more pieces between 3/8 and 1/2 inch, so it is slightly coarser than #8.

How much does a yard of #78 stone weigh?

Usually about 1.35 to 1.5 tons per cubic yard, or roughly 2,700 to 3,000 pounds. Use 1.4 tons per yard for planning unless the quarry gives its own figure.

Is #78 stone good for a driveway?

It works as a thin top dressing over a compacted dense-graded base such as crusher run. A thick layer of #78 alone shifts and ruts because it has few fines to bind it.

Is #78 stone good for drainage?

It drains better than dense base or stone dust, but larger clean stone such as #57 carries much more water and is the usual pick for French drains.

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