#57 Gravel vs Compost: Size, Cost, and Which to Use

#57 Gravel

The 57 comes from the ASTM C33 grading table. Size #57 means most of the stone passes a 1-inch screen and stays on a #4 sieve (about 3/16 inch), with the bulk of it between 1/2 and 1 inch. It is "clean" stone, so there are no fines. That leaves about 35 percent air space in a pile, which is why it drains so well and why it stays loose on its own.

Compost

Decomposed organic matter used as a soil amendment to improve soil structure, fertility, and water retention. Quality compost is dark, crumbly, and earthy-smelling. It adds beneficial microorganisms and nutrients that support healthy plant growth and improve poor soils.

#57 Gravel

• ✓ Driveways
• ✓ French drains
• ✓ Concrete mix
• ✓ Pipe bedding
• ✓ Backfill
• ✓ Parking pads
• ✓ Septic systems

Compost

• ✓ Soil amendment
• ✓ Garden beds
• ✓ Lawn top-dressing
• ✓ Raised beds
• ✓ Tree and shrub planting
• ✓ Seed starting mix

#57 Gravel

• + Cheapest useful stone at $20 to $35 per ton
• + Stocked at every quarry in the country
• + Drains fast, about 35 percent void space
• + Angular pieces interlock under load
• + Works for driveways, drains, concrete, and backfill

• − Too coarse to walk on comfortably
• − Stays loose, rolls to the edges under tires
• − Needs a finer top layer on driveways
• − Not decorative

Compost

• + Dramatically improves soil structure and fertility
• + Increases water retention in sandy soils
• + Improves drainage in clay soils
• + Adds beneficial microorganisms
• + Reduces need for chemical fertilizers

• − Quality and composition vary widely between sources
• − Can be odorous when fresh
• − May contain weed seeds if not fully composted
• − Too rich for direct planting — must be mixed with soil
• − Settles significantly after application

#57 Gravel

#57 gravel is angular crushed stone screened to 3/4 inch to 1 inch, with a few pieces down to 1/2 inch. Color depends on the quarry: gray or blue-gray limestone through the Midwest and Northeast, gray, white, and pink granite in the Southeast, tan limestone in Texas, and dark basalt in the Northwest.

Compost

Fine, crumbly texture when fully decomposed. Dark brown to black color. Should smell earthy, not sour or ammonia-like. Screened compost has been filtered to remove large uncomposted pieces. Mushroom compost is a byproduct of mushroom farming and is particularly nutrient-rich.