Cement is a powder. Concrete is the finished material made by mixing cement with sand, gravel and water. A sidewalk is made of concrete, and cement is the ingredient that binds it together.
The three terms
| Material | What it is | Used for |
|---|---|---|
| Cement | A fine powder that hardens when mixed with water | An ingredient in concrete and mortar |
| Concrete | Cement + sand + gravel + water | Slabs, footings, posts, walls |
| Mortar | Cement + sand + water, with no gravel | Laying brick and block |
What to buy
- Concrete mix for slabs, footings, steps and posts. The bag already contains cement, sand and gravel. You add water.
- Mortar mix for laying brick, block or stone.
- Portland cement only if you are mixing your own concrete or mortar from separate materials.
Why the mix-up matters
A bag labeled cement is not a bag of concrete. Mixed with water alone it makes a paste that shrinks and cracks. If your project needs concrete, check that the bag says concrete mix.
How much do you need?
Either way, the first step is the volume. Use the concrete calculator for slabs, footings and posts, or the concrete block calculator for block walls. If you are mixing from separate materials, see concrete mix ratio.
Frequently asked questions
Is cement the same as concrete?
No. Cement is one ingredient of concrete. Concrete is cement mixed with sand, gravel and water.
Should I buy cement or concrete mix for a slab?
For a slab or post, buy concrete mix, which already contains cement, sand and gravel. Plain cement is for people mixing their own concrete or mortar.
Is a cement calculator the same as a concrete calculator?
In everyday use, yes. When people look for a cement calculator for a slab or footing, they need the volume of concrete, which is what a concrete calculator gives.