Two units, one density
Gravel is the material where the unit question matters most, because it is bought by volume, sold by weight, and moved by the bucket. The bridge between the two is a density, and the density is a property of the stone:
cubic yards per ton = 1 ÷ tons per cubic yard
tons = cubic yards × tons per cubic yard
River rock 1.35 t/yd · pea gravel 1.4 · crushed stone #57 1.45 · crusher run 1.5
Read the table below as an exchange rate rather than a conversion factor. The heavier the stone, the fewer yards a ton buys — which is the opposite of what most people expect, because “a ton of gravel” sounds like a fixed pile.
Chart: yards per ton, four materials
Lightest material first. The bags column is fixed at 40 because a short ton is 2,000 lb and a bag is 50.
| Material | Tons / yd | Yards / ton | 50 lb bags / ton |
|---|---|---|---|
| River Rock / Smooth Pebble | 1.35 | 0.741 | 40 |
| Pea Gravel (3/8") | 1.4 | 0.714 | 40 |
| Crushed Stone #57 | 1.45 | 0.690 | 40 |
| Crusher Run / Dense Grade Base | 1.5 | 0.667 | 40 |
The spread is 0.07 of a yard per ton between river rock and crusher run — which sounds like nothing until it multiplies. On a 20-ton order it is 1.4 cubic yards, or roughly a pickup bed of stone you paid for and did not get, or got and did not pay for.
Chart: 1, 5, and 10 tons in cubic yards
The direct answer for an order that starts in tons. These are exact divisions, printed to three decimals so you can see where the rounding falls.
| Material | 1 ton | 5 tons | 10 tons |
|---|---|---|---|
| River Rock / Smooth Pebble | 0.741 | 3.704 | 7.407 |
| Pea Gravel (3/8") | 0.714 | 3.571 | 7.143 |
| Crushed Stone #57 | 0.690 | 3.448 | 6.897 |
| Crusher Run / Dense Grade Base | 0.667 | 3.333 | 6.667 |
Ten tons of crushed stone is 6.9 yards, which is the size of a small dump-truck load and enough to cover about 745 square feet at 3 inches. Ten tons of river rock is 7.4 yards and covers more ground, because the lighter stone spreads thinner for the same weight. That second fact is why the coverage-per-ton guide and this one have to be read together: one answers how far a ton goes, the other answers how big a ton is.
Chart: five yards, weighed in each material
The reverse direction, and the one a delivery ticket forces on you. Five cubic yards is five cubic yards — the loader does not care what is in the bucket — but the weight on the axle changes with the material.
| Material | Cubic yards | Tons | 50 lb bags |
|---|---|---|---|
| River Rock / Smooth Pebble | 5 | 6.8 | 272 |
| Pea Gravel (3/8") | 5 | 7 | 280 |
| Crushed Stone #57 | 5 | 7.3 | 292 |
| Crusher Run / Dense Grade Base | 5 | 7.5 | 300 |
Same five yards, 28 bags apart between river rock and crusher run. The bag column is not a recommendation — 272 bags is a pallet-and-a-half and a very long afternoon — it is the scale that makes the weight difference visible. Past a yard or two, bulk is the only sensible order.
Bags to a ton, tons to a yard, yards to a bag
Three conversions, and it is worth keeping them in order. A ton is 40 bags of 50 lb, always. A yard of crushed stone is 1.45 tons, which is 58 bags. A ton is 0.69 of a yard. The only one of those that changes with material is the yard figure, because it is the only one that runs through density.
Which means the bag count is a bad unit for bulk and a good unit for a wheelbarrow job. A single yard of crushed stone is 58 bags: more handling than a ton delivered to the driveway, and the same material. The trench guide uses that crossover at about 30 feet of drain, where the order flips from bags to bulk.
Why the supplier quotes a different number
- Moisture. Wet stone weighs more per yard, and a yard measured after a rain can be 5 to 10% heavier than the same yard in August. The ticket is priced on weight at the scale, not on the density in a table.
- Compaction and handling. A loader bucket heaped is not a cubic yard, and a pile that has sat for a year is denser than one that just came off the screen. Suppliers work from their own long-run average, which is why their yards-per-ton is close to but rarely identical to yours.
- Product naming. “#57 stone” is a gradation, not a density: a #57 from one quarry can be a different rock from another. Crusher run and dense-grade base are the heaviest of the common products because the fines fill the voids.
- Rounding. The calculator rounds yards up to a quarter and tons up to a tenth, both upward. A supplier quoting to two decimals may be rounding to nearest, which is how a 7.25-ton order becomes 7.2 on one ticket and 7.3 on another.
The mistakes that cost a load
01
Using one yards-per-ton number for every material
The figure that gets repeated online is 0.75, which is close to river rock and wrong for crusher run. Denser material packs more weight into the same volume, so the yardage per ton goes down as the density goes up — 0.74 for river rock against 0.67 for a dense-grade base. Order 10 tons of the wrong one and you are three quarters of a yard out.
02
Converting at the bag instead of at the yard
A ton is 40 bags of 50 lb, which makes bags feel like the natural unit. They are the retail unit. Bulk is sold by the cubic yard, delivered on a ticket that says yards, and the conversion runs through density — not through bags. Two conversions at once is how an order ends up short by a couple of wheelbarrows.
03
Ordering the exact volume
Gravel settles, spills, and disappears into a soft subgrade. A 5 cubic yard order spread at 3 inches covers 540 square feet on paper and rather less in the driveway. Order the next quarter yard up; the calculator rounds that way already, and the extra is a fraction of a ton on most materials.
04
Mixing short tons and metric tonnes
A US short ton is 2,000 lb; a metric tonne is 2,204.6 lb. That is a 10% difference, which on a 30-ton order is three tons. Aggregate yards in the US quote short tons, but a spec sheet or an imported product may not, and the units are rarely spelled out.
05
Trusting the rule that a yard is a ton
It is a serviceable shorthand for topsoil, not for stone. Every material on this page is heavier than a ton per yard, from 1.35 to 1.5, so the rule underestimates the ticket by a third to a half. It also makes the reverse question — how many yards in a ton — come out as one, which is never right.
Run your own order
The link below opens the gravel calculator on a 45-foot by 3-foot area at 12 inches deep — exactly 135 cubic feet, 5 cubic yards, 7.3 tons, and 292 bags of crushed stone. Change the material and the yardage stays at 5 while the tonnage and bag count move; change the depth and all three move.
Open the gravel calculator with this order filled in — the tonnage, the cubic yards, and the bag count come out of one box calculation. For a driveway built in layers, the layers guide runs this arithmetic three times.