How Much Concrete is Needed for a Stable Foundation?

Concrete consumption can be hard to estimate. Here is how you calculate the volume accurately.

Pouring a stable concrete foundation or footing is the basis for every successful deck or shed build. To calculate how much concrete you need, you must first determine the number of footings and their dimensions (diameter and depth). Generally, it takes about 0.6 to 1.0 cubic feet of concrete per footing (which corresponds to 1-2 standard 80 lb bags) if you dig to the frost line and use an 8-inch cardboard tube form. It is always better to mix a little extra than to stand with a half-poured footing when the concrete runs out.

Digging to the Frost Line

One of the most critical aspects of pouring footings is ensuring you dig below the frost line in your local area. If you pour a footing above the frost line, the moisture in the soil beneath it will freeze during winter, expand, and push the footing upwards (frost heave). This can severely warp your deck or structure. Always check with your local building department to find out the exact frost depth requirement in your region.

Mixing the Concrete

When mixing concrete in a wheelbarrow, consistency is key. You want it to look like thick oatmeal. If you add too much water, you severely weaken the final strength of the concrete. Add water slowly, mix thoroughly, and ensure there is no dry powder left at the bottom of the wheelbarrow before pouring.

Summary

Accurate calculations prevent the stress of running to the store mid-pour with wet concrete hardening in your wheelbarrow. Use our Concrete Footing Calculator to get the exact number of bags you need, factor in a 10% waste margin, and ensure you dig deep enough to beat the frost.