MyYardCalcHow many bags of concrete are in a yard?
Divide 27 cubic feet by the mixed yield of one bag. If your chosen 80 lb bag yields 0.60 cu ft, one cubic yard takes 45 bags before allowance. The bag weight alone does not guarantee its yield.
Use mixed yield, not dry volume
Concrete bags contain dry ingredients, while the finished pour needs a volume of mixed concrete. Find the product’s stated yield after mixing. Do not enter 80 as a bag volume because the package weighs 80 lb, and do not use a mortar, cement-only or other product’s yield for a different mix.
Illustrative bag sizes and yields
| Example bag weight | Assumed mixed yield | Bags for 1 cu yd |
|---|---|---|
| 40 lb | 0.30 cu ft | 90 |
| 60 lb | 0.45 cu ft | 60 |
| 80 lb | 0.60 cu ft | 45 |
These rows illustrate the arithmetic and are not specifications for every product at those weights. Fibres, lightweight aggregates, mix design and packaging can change the yield. Follow the selected product’s mixing instructions; changing water content is not a way to stretch a quantity estimate.
Example: a 10 by 10 foot slab
With an illustrative thickness of 4 inches, a 100 sq ft slab occupies 100 × 4 ÷ 12 = 33.3333 cu ft, or 1.23457 cu yd. At the example yield of 0.60 cu ft, this takes 56 whole bags before allowance.
If the order calls for a 10% allowance, calculate from the unrounded volume: 33.3333 × 1.10 ÷ 0.60 = 61.1111 bags, rounded to 62. Do not round the base bag count first and then multiply by the allowance. The thickness and allowance are demonstration inputs, not a structural design.
Footings, edges and columns need their own geometry
A simple slab footprint does not include steps or thickened edges automatically. Calculate each separate volume, avoiding overlaps. The concrete calculator supports rectangular pours, round columns and hollow cylinders. The slab calculator focuses on a flat layer.
For a thickened edge, count the main slab once, then add only the edge volume extending beyond its regular thickness. Use dimensions from the project design and include separate footings as separate pours.
When the package yield uses litres
One cubic meter contains 1,000 litres. A pour of 0.25 m³ with a product yielding an illustrative 12 L per bag needs 250 ÷ 12 = 20.8333 bags, rounded to 21 before allowance. In Metric mode, enter the mixed yield in litres; in US mode, enter cubic feet.
Compare a complete material quote
Multiply whole bags by the bag price or compare a ready-mix volume quote with its delivery charge. Check minimum orders, short-load fees and supplier increments before deciding. Forms, reinforcement, pumping, finishing, labor and taxes are outside this material quantity calculation.
Estimate your concrete volume and bags →
See our formulas and rounding rules. Reinforcement quantities can be estimated separately with the rebar calculator using the spacing and cover specified for the design.