Estimate how many bags of cement you need for a concrete pour, based on the pour volume and bags per cubic yard.
cement bags = volume_yd³ × bags_per_yd³
A typical concrete mix uses about 6 bags of cement per cubic yard. Adjust the ratio for higher-strength mixes.
Cement is the binder; concrete is cement plus sand and aggregate. This estimates the cement portion of a site mix.
Concrete is a recipe, and the cement portion depends on the strength you're after. A common general-purpose mix uses roughly six bags of cement per cubic yard along with sand and aggregate in proportions like 1 part cement to 2 parts sand to 3 parts stone. Higher-strength mixes — for structural columns or heavy-duty slabs — use more cement per yard, often seven or eight bags, which is why they cost more.
If you're batching concrete on site, this calculator estimates the cement binder you'll need; you still buy sand and aggregate separately and combine them on site. The advantage of site-batching is control and the ability to mix small amounts as you go. The disadvantage is consistency — a ready-mix plant batches to a precise, tested recipe every time, which is hard to match by hand.
For small repairs and pours, pre-blended bagged concrete — cement, sand, and stone already combined — is simpler: just add water. Use the concrete slab calculator for those, since it counts finished bags directly. Site-batching from separate cement, sand, and aggregate makes sense when you need a specific mix design, want to control the proportions, or are doing enough volume that buying materials separately is cheaper than pre-mixed bags.
Either way, keep cement dry until use — it absorbs moisture from the air and hardens in the bag. Buy what you'll use reasonably soon, store it off the ground and covered, and check that bags are still loose and powdery before mixing.
For a 10 x 10 ft shed slab at 4 inches, the volume is 33.3 cubic feet or 1.23 cubic yards. At a general-purpose ratio of about 6 bags of cement per cubic yard, that's roughly 8 bags of cement — plus the sand and aggregate that turn cement into concrete.
Remember this calculator estimates the cement binder portion of a site-batched mix. If you're buying pre-blended bagged concrete instead (cement, sand, and stone already combined), use the concrete slab calculator, which counts finished bags directly.
Bags-per-yard varies with mix design and strength. Six bags per cubic yard is a common general-purpose ratio — confirm for your spec.
About 6 for a standard mix; high-strength mixes use 7–8.
About six bags of cement for a standard mix, combined with roughly 0.5 cubic yards of sand and 0.75 cubic yards of aggregate. Stronger mixes use seven to eight bags.
A common general-purpose ratio is 1 part cement to 2 parts sand to 3 parts aggregate (1:2:3) by volume, with water added to reach a workable consistency. Stronger mixes use proportionally more cement.
Yes, if you keep it completely dry — off the ground, sealed, and covered. Cement absorbs moisture and will harden in the bag over time, so use it within a few months and discard any that has lumps.