3/4 Minus Gravel: What It Is, Weight and How Many Tons

3/4 minus gravel is crushed rock that runs from about 3/4 inch down to fine dust. The word “minus” tells you that everything smaller than the top size stays in the pile, so along with the 3/4-inch pieces you get chips, coarse sand and rock flour. That mix is the whole point. Dampen it, run a compactor over it, and the small particles fill the gaps between the larger ones until the layer turns firm and stops shifting underfoot. Rock yards across Washington, Oregon, Idaho, northern California and much of the West sell it as their everyday base and driveway rock. For planning, figure about 1.8 tons of 3/4 minus for each cubic yard of finished, compacted layer. This guide covers what the name means, how it compares with clean rock and other minus sizes, where it works, how deep to lay it and how to work out the tons.

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What “3/4 minus” means

Western yards name crushed rock by the largest screen it passes and by whether the small stuff was kept or removed. 3/4 minus, also written 3/4"-0, 3/4 inch minus or 3/4 crushed with fines, passes a 3/4-inch screen and keeps every size below it. 3/4 clean passes the same screen, but the fines have been screened or washed out, so it is stone and nothing else. That one difference decides how the rock behaves: minus locks together into a hard layer, while clean rock stays loose and lets water through.

There is no single national recipe. One yard may crush quarried basalt, another may crush river gravel, and the share of fines changes from one source to the next. In Oregon, road plans and delivery tickets describe dense base rock by its size range, so “3/4"-0” is a common way to see it written. In Washington, the closest state product is Crushed Surfacing Top Course, or CSTC. It is usually sold as 5/8 minus, yet its specification requires nearly all of it to pass the 3/4-inch screen, so some yards treat the two as near substitutes. If a permit or plan names a spec, ask the yard which one its rock is tested to.

For a sense of how much fine material a rock in this size class carries, here is the Washington top course gradation in round numbers. Treat it as a reference point, not a description of every 3/4 minus on the market.

Sieve opening	Share passing (by weight)
3/4 inch	99 to 100%
1/2 inch	80 to 100%
No. 4 (about 3/16 inch)	46 to 66%
No. 40	8 to 24%
No. 200 (dust)	10% or less

About half of the rock by weight is smaller than 3/16 inch. That is a lot of fine material compared with a clean stone, and it explains both the strength of a compacted minus layer and its main weakness, which is slow drainage.

3/4 minus vs other crushed rock

Product	Size range	Fines?	Typical use
3/4 minus	3/4 inch down to dust	Yes	Driveway base and surface, shed and patio pads, paths
5/8 minus (top course)	About 5/8 inch down to dust	Yes	Smooth driveway surface, topping a coarser base
1 1/4 minus (base course)	About 1 1/4 inch down to dust	Yes	Lower base layer for driveways and roads that carry heavier loads
1/4 minus	1/4 inch down to dust	Yes	Bedding for pavers and flagstone, fine path surface
3/4 clean	About 3/4 inch, no fines	No	Drainage, French drains, behind retaining walls

East of the Rockies, the same idea of crushed stone with its own dust is sold under other names: crusher run, road base, and state blends such as ABC in North Carolina, 2A modified in Pennsylvania and 21A in Virginia. Those products often top out at 1 to 1 1/2 inches, so 3/4 minus sits on the finer side of the family. Its smaller top size makes a smoother surface, while the coarser blends make a slightly stronger bottom layer.

Where 3/4 minus works well

Gravel driveways. On a driveway that sees cars and pickups, 3/4 minus can serve as both base and surface. On longer drives or soft ground, many builders put down 1 1/4 minus first and finish with a few inches of 3/4 minus for a tighter top. Our guide on how to build a gravel driveway walks through the layers.
Base under asphalt or concrete. A compacted layer of minus rock gives pavement an even, firm bed that will not settle in spots.
Shed, hot tub and equipment pads. It levels easily and packs hard. For a hot tub, check the maker’s base requirements before you build.
Paver patios and walks. It works as the compacted base, with a thin bedding layer of sand or 1/4 minus above it for setting the pavers.
Garden paths. It firms up into a walkable path that is easier on wheelbarrows than loose stone.

Where it falls short

The fines that make 3/4 minus pack so well also slow water down. It is the wrong choice for a French drain, the backfill zone behind a retaining wall, or the stone around a foundation drain. Use a clean rock there. As a driveway surface, it slowly loses its fines to rain, wind and tires, which leaves loose stone on top and potholes in low spots, so plan on regrading and adding a few tons every few years. Spread over soft mud with nothing in between, it gets pushed down into the soil; a geotextile fabric under the rock keeps the two apart.

How much 3/4 minus weighs

Loose, as it comes off the truck, 3/4 minus commonly weighs about 1.35 to 1.5 tons per cubic yard, or roughly 2,700 to 3,000 pounds. Compaction squeezes out much of the air, so one cubic yard of finished layer takes more rock, often about 1.8 tons. Basalt runs heavier than some crushed river rock, and wet rock weighs more than dry. If your yard quotes its own weight per yard, use that number. The gravel weight per yard chart lists other materials.

Many western yards sell rock by the cubic yard instead of the ton. When they do, they mean a loose yard as it is loaded. Because the layer shrinks as you compact it, ten loose yards end up as roughly eight yards of compacted base.

How deep to lay it

Walks and paver patios: about 4 inches compacted.
Car driveways on firm, well-drained ground: 4 to 6 inches compacted of 3/4 minus alone, or about 4 inches of 1 1/4 minus topped with 2 inches of 3/4 minus.
Soft or wet ground, or heavy trucks: a thicker base, often with larger rock underneath and fabric on the soil.
Refreshing an existing driveway: 1 to 2 inches over a regraded surface.

These are starting points. If a contractor, engineer or local permit sets a depth, follow it.

How many tons of 3/4 minus you need

Measure the area in square feet and pick the compacted depth in inches. Then use:

Tons ≈ area (sq ft) × compacted depth (in) × 0.0055
Area one ton covers ≈ 180 ÷ compacted depth (in), in square feet
Loose cubic yards to order ≈ area (sq ft) × compacted depth (in) ÷ 324 × 1.25

The 0.0055 factor assumes about 1.8 tons per compacted cubic yard, so the extra rock that compaction takes is already built in. Add 5 to 10 percent for uneven ground, soft spots and edges.

Compacted depth	Approx. area one ton covers	Tons per 100 sq ft
2 inches	about 90 sq ft	about 1.1
4 inches	about 45 sq ft	about 2.2
6 inches	about 30 sq ft	about 3.3

Example: topping a 12 by 60 foot driveway with 4 inches. 12 × 60 = 720 square feet. 720 × 4 × 0.0055 = about 15.8 tons, so order 16 to 17 tons. If the yard sells by the yard: 720 × 4 ÷ 324 = about 8.9 compacted yards, times 1.25 is about 11 loose yards. Our guide to tons of gravel in a dump truck explains how many loads that is.

Example: a 10 by 12 foot shed pad, 4 inches compacted. 10 × 12 = 120 square feet. 120 × 4 × 0.0055 = about 2.6 tons. Order about 3 tons, or 2 loose yards.

Laying and compacting 3/4 minus

Strip sod, topsoil and soft material down to firm ground, and shape the soil so water will run off the finished surface.
Lay fabric where the soil is clay, wet or soft.
Spread the rock in lifts of about 3 to 4 inches. A plate compactor cannot pack the bottom of a much thicker layer.
Dampen the rock so it is moist but not soupy, then make several passes with a plate compactor or roller until it stops moving under your boots. Compacting a gravel base in lifts goes step by step.
Finish with a crown or a steady slope so rain sheds off instead of soaking in.

Buying tips

Ask for crushed rock. Crushed pieces with sharp, fractured faces lock together. Rounded, uncrushed gravel with sand mixed in, often sold as pit run, does not pack the same way.
Ask the weight per yard if the yard sells by volume, so you can compare prices with yards that sell by the ton.
Price it delivered. Hauling often costs as much as the rock. A closer yard can beat a lower price per ton farther away.
Bags vs bulk. Bagged paver base from a home center is often a similar crushed rock with fines. It is handy for a few square feet, but anything the size of a shed pad is usually far cheaper in bulk.
Plan the drop spot. A loaded dump truck is heavy. Keep it off septic fields, soft lawn and thin pavement.

Questions people ask

What is 3/4 minus gravel?

It is crushed rock that passes a 3/4-inch screen and keeps all the smaller pieces, down to dust. The fines let it compact into a firm, stable layer, which makes it a common base and surface rock for driveways, pads and paths, especially in the western states.

What is the difference between 3/4 minus and 3/4 clean?

Both top out at about 3/4 inch. 3/4 minus keeps its fines, so it packs hard but drains slowly. 3/4 clean has the fines removed, so it stays loose and lets water pass, which suits drainage work rather than a load-bearing base.

How much does a yard of 3/4 minus weigh?

Loose 3/4 minus commonly weighs about 1.35 to 1.5 tons per cubic yard, roughly 2,700 to 3,000 pounds. A cubic yard of compacted layer takes about 1.8 tons. Rock type and moisture change the number, so use your supplier's figure when you have it.

How much area does a ton of 3/4 minus cover?

At about 1.8 tons per compacted cubic yard, one ton covers roughly 90 square feet at 2 inches, 45 square feet at 4 inches, or 30 square feet at 6 inches compacted.

Is 3/4 minus good for a driveway?

Yes. It compacts into a drivable surface and works as both base and top layer on many home driveways. On soft ground or long drives, a coarser 1 1/4 minus base with 3/4 minus on top holds up better. Expect to regrade and add rock every few years.

Does 3/4 minus drain well?

Not very well. The fines that help it pack also slow water down. It sheds water when graded with a crown or slope, but for French drains, wall backfill or foundation drains, use a clean rock instead.

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