Concrete Bag Calculator

What Is Bag Concrete?

The concrete bag calculator above estimates how many 40, 60, or 80 lb bags you need for your project — bag concrete (also called sack concrete or pre-mixed concrete) is a dry blend of Portland cement, sand, and gravel that is factory-proportioned and sold in these standard sizes. You add water and mix on-site. The main advantage is convenience — no minimum order, no delivery truck, and you only mix what you need. Standard bagged mixes produce concrete in the 3,000–4,000 PSI range, which is adequate for most residential applications including fence posts, slabs, steps, and footings. Quikrete and Sakrete are the two dominant national brands; both are widely available at Home Depot and Lowe's.

Bag concrete is most economical for small projects under about 1 cubic yard. Above that threshold, ready-mix concrete delivered by truck — typically $110–$165 per cubic yard — becomes significantly cheaper than buying individual bags at the retail equivalent of $200–$350 per cubic yard.

How Many Bags of Concrete Do You Need?

This bag concrete calculator determines exactly how many bags you need by first finding the volume of your project in cubic feet, then dividing by the coverage per bag. Whether you call it a sack of concrete or a bag, the coverage is the same — one 60-lb sack of concrete fills roughly 0.40 cubic feet. Use our concrete calculator if your project includes multiple shapes like columns or footings alongside a slab.

• 40 lb bag: 1 bag = 0.27 ft³ → bags needed = volume ÷ 0.27
• 60 lb bag: 1 bag = 0.40 ft³ → bags needed = volume ÷ 0.40
• 80 lb bag: 1 bag = 0.53 ft³ → bags needed = volume ÷ 0.53

Always round up to the nearest whole bag and add 10% extra for waste.

Quikrete vs. Sakrete — What Is the Difference?

Quikrete and Sakrete are the two most popular bag concrete brands in the United States. Both produce high-quality concrete mixes with the same coverage rates. The key differences are:

• Availability: Both Quikrete and Sakrete bags are widely available at Home Depot and Lowe's. Quikrete has broader national distribution; Sakrete has strong regional presence in the Southeast.
• Price: Both brands are comparably priced — check your local Home Depot or Lowe's for current per-bag pricing.
• Mixes: Both offer concrete mix, mortar mix, sand mix, fast-setting concrete, and fiber-reinforced options.

Bags of Concrete for Common Projects

• Fence post (8 in hole, 2 ft deep): 2 bags (80 lb) per post
• 10×10 patio (4 in thick): 84 bags (60 lb) or 63 bags (80 lb) — see the concrete slab calculator for larger slab estimates
• Sonotube 12 in dia, 3 ft deep: 6 bags (60 lb) or 5 bags (80 lb)
• Sidewalk 3 ft × 20 ft (4 in thick): 50 bags (60 lb) or 38 bags (80 lb)

Tips for Mixing Bag Concrete

• Mix concrete in a wheelbarrow or rented mixer — do not mix directly on the ground
• Add water gradually — too much water weakens concrete
• A standard 80 lb bag typically requires about 3 quarts of water
• For fast-setting concrete (like Quikrete Fast Setting), pour dry into the hole and add water on top — no mixing required
• Wear gloves and eye protection — concrete is caustic

Concrete Bag Prices and Cost Per Cubic Yard

Bag concrete prices vary by brand, bag size, and retailer. As of 2025–2026, typical retail prices at Home Depot and Lowe's are:

• 40 lb bag — $3.50–$4.50 per bag (~$350–$450 per cubic yard)
• 60 lb bag — $5.00–$6.50 per bag (~$340–$440 per cubic yard)
• 80 lb bag — $6.50–$8.00 per bag (~$330–$405 per cubic yard)

Larger bags are more cost-effective per cubic yard, but heavier to handle. For projects over 1 cubic yard (~40 bags of 80 lb), ready-mix delivery at $110–$165 per cubic yard is significantly cheaper. Use our concrete cost calculator to compare bag vs. ready-mix pricing for your project size.