Concrete Calculator for Bags, Gravel, and Mulch

You need 56 bags (57 with a 10% waste buffer). Formula: cubic feet = 10 × 10 × (4/12) = 33.33 cubic feet, then divide by bag yield and round up.

About 222 bags of 80lb, or 297 bags of 60lb.

It is 1.23 cubic yards.

A cubic yard of concrete weighs approximately 4,050 lb (around 2 tons). Ready-mix and bagged mixes can vary slightly by aggregate and moisture content.

You need approximately 3.1 tons (use the calculator for exact values for your depth and area).

Plan for 4 inches for light vehicles and 6 inches for heavy vehicles.

You need 13 bags (2 cu ft) or 9 bags (3 cu ft).

Cubic yards measure volume, while tons measure weight. Gravel ordering often uses a conversion of about 1 cubic yard ≈ 1.4 tons, but suppliers may use slightly different factors by stone type.

One cubic yard of concrete requires approximately 45 bags of 80 lb concrete mix, 60 bags of 60 lb mix, or 90 bags of 40 lb mix. This is because one cubic yard equals 27 cubic feet, and each bag yields 0.60, 0.45, or 0.30 cubic feet respectively.

A 4-inch thick 10×10 slab requires 1.23 cubic yards or 33.3 cubic feet of concrete. Using 60 lb bags (0.45 cu ft each), you need approximately 74 bags. Add 10% for waste: 82 bags total.

Cement is an ingredient in concrete. It is the binding powder (usually Portland cement) that, when mixed with water, sand, and gravel, forms concrete. Concrete is the final hardened material used for slabs, footings, and foundations. When you buy bags at the hardware store labeled "concrete mix," the cement is already included.

One cubic yard of gravel weighs approximately 1.4 tons (2,800 pounds) for standard crushed stone. Lighter materials like pea gravel weigh closer to 1.2–1.3 tons per yard, while denser materials like river rock can weigh up to 1.6 tons per yard.

A cubic yard of gravel typically weighs between 2,700 and 2,900 pounds, depending on the type and moisture content. Dry crushed stone averages about 2,835 pounds per cubic yard, which equals approximately 1.42 tons.

Recommended gravel depths by use: decorative landscaping and foot traffic paths: 2 inches; residential driveways with light vehicles: 4 inches; driveways with heavy trucks or frequent traffic: 6 inches; French drains and drainage projects: 6 to 12 inches. When in doubt, 4 inches is the standard starting point for most residential projects.

13.5 bags (2 cu ft) or 9 bags (3 cu ft) per cubic yard. One cubic yard equals 27 cubic feet of mulch; 2 cubic foot bags are the most common size, so round 13.5 up to 14 bags when buying. If using 1.5 cubic foot bags (common at Home Depot), you need 18 bags per cubic yard.

Apply 2 to 3 inches of mulch for established garden beds and around perennial plants. Use 3 to 4 inches for new beds, around trees, or to suppress weeds. Never pile mulch against plant stems or tree trunks; keep a 2 to 3 inch gap to prevent rot. Refresh mulch annually when depth drops below 2 inches.

Bulk mulch delivered by the cubic yard is almost always cheaper per unit, typically 40 to 60% less than bagged mulch on a per-cubic-foot basis. However, bags are more convenient for small projects, easy to transport in a car, and available in more color options. If you need more than 2 cubic yards, bulk delivery usually saves money. Under 1 cubic yard, bags are often more practical.

For a standard 4×4 fence post in a 10-inch diameter hole at 24 inches deep, you need approximately 0.76 cubic feet of concrete per hole, about 1.5 bags of 80 lb concrete. For 10 posts, that is 15 bags plus 10% waste buffer, so 17 bags total. Use the Post Holes tab above to calculate your exact project.

The standard rule is that the hole depth should equal one-third of the total post length, with a minimum of 24 inches. For a 6-foot fence (8-foot post), the hole should be at least 24 to 30 inches deep. In areas with frost, holes should extend below the local frost line, which can be 36 to 48 inches in northern climates.