Concrete vs. Cement: What's the Difference?
Clearing up the most commonly confused terms in the trade.
People use “cement” and “concrete” as if they mean the same thing, but they are different materials. Cement is one ingredient. Concrete is the finished mixture. Getting the words right helps you buy the correct product and avoid an expensive mistake at the store.
Cement Is an Ingredient
Portland cement is a fine grey powder made by heating limestone and clay to a very high temperature and grinding the result. On its own it is not a building material. When it is mixed with water, it forms a paste that hardens and binds other materials together. Cement typically makes up roughly 10–15% of the volume of a concrete mix.
Concrete Is the Finished Product
Concrete is a mixture of cement, water, sand (fine aggregate), and gravel or crushed stone (coarse aggregate). As the cement paste cures, it locks the aggregate into one solid mass. The sidewalk, driveway, patio, or footing you are planning is made of concrete, not cement. The often-heard phrase “cement driveway” is really a concrete driveway.
Concrete vs Cement vs Mortar
| Material | What it contains | Typical use |
|---|---|---|
| Cement | Portland cement powder only | An ingredient. Used to make concrete, mortar, and grout. |
| Concrete | Cement, water, sand, and gravel or stone | Slabs, driveways, footings, sidewalks, foundations. |
| Mortar | Cement, water, and sand (no coarse stone) | Bonding bricks and blocks, and stone. |
What to Buy for a DIY Project
For a slab, footing, post hole, or step, buy bags labeled concrete mix. They already contain cement, sand, and gravel in the right proportions, so you add water and mix. If you buy a bag labeled Portland cement, you would still need to add your own sand and gravel, which is more work and easy to get wrong. Bags of mortar mix are for laying brick and block and do not have the coarse stone needed for slabs. Fast-setting concrete mixes are useful for fence posts, where you want a quick set.
Strength Ratings
Concrete strength is rated in pounds per square inch (psi). Residential slabs, driveways, and footings commonly use mixes in the 3,000–4,000 psi range. Ordering ready-mix, you can specify the strength you need. Bagged mixes state their strength on the label. The strength of the concrete depends on the water-to-cement ratio, the quality of the aggregate, and how well it is cured, not only on the amount of cement.
Common Mix-Ups
- Asking for “a bag of cement” when you need concrete mix.
- Assuming more cement always makes stronger concrete. Too much cement or too much water can cause shrinkage and cracking.
- Using mortar mix for a slab. It lacks coarse aggregate and will not perform like concrete.
Once you know you need concrete, work out how much: the Concrete Calculator on this site converts your slab, footing, or column dimensions into cubic yards and bag counts.