Concrete Calculator

Q1. How much concrete do I need for my project?

To find how much concrete you need, multiply the length, width, and depth of your slab in feet to get cubic feet, then divide by 27 to convert to cubic yards (the unit concrete is sold in). For example, a 10 ft x 10 ft slab poured 4 inches deep is 10 x 10 x 0.33 = 33 cubic feet, or about 1.23 cubic yards. Always add 5 to 10% extra to cover spillage, uneven subgrade, and over-excavation. Our Concrete Calculator does this for you and includes a built-in waste allowance.

Q2. Should I use bagged concrete mix or order ready-mix?

Bagged concrete mix is most practical for small jobs—setting posts, small pads, footings, and repairs—because you mix only what you need with a wheelbarrow or mixer. Ready-mix delivered by truck makes sense for larger pours like driveways, patios, and foundations, where mixing dozens of bags by hand becomes impractical and the pour needs to happen continuously for a strong, seamless slab. A rough rule of thumb: once you approach a full cubic yard, ready-mix usually saves time and produces a more uniform result.

Q3. What is the right thickness for a concrete slab?

For most residential applications, 4 inches is the standard slab thickness—this works for patios, walkways, shed floors, and garden slabs. For driveways that carry regular passenger vehicles, pour at least 4 inches, and step up to 5 to 6 inches if heavy trucks, RVs, or trailers will park on it. Garage floors are typically 4 to 6 inches. Thicker slabs need more concrete, so always confirm the depth before calculating volume, and check your local building code, since some areas require a minimum thickness or reinforcement.

Q4. Do I need rebar or wire mesh in my concrete?

Reinforcement helps concrete resist cracking and adds strength under load. Welded wire mesh is common for residential slabs, patios, and sidewalks to control cracking, while rebar is used for thicker slabs, driveways carrying heavy vehicles, footings, and structural work. The reinforcement should sit in the middle of the slab’s thickness, supported on chairs so it doesn’t end up at the bottom. Smaller decorative or non-load-bearing pours may use fiber-reinforced mix instead. Check local code, since requirements vary by application.

Q5. How long does concrete take to cure?

Concrete sets enough to walk on within 24 to 48 hours, but full curing takes about 28 days to reach its rated strength. You can typically remove forms after 24 to 48 hours, drive light vehicles on it after about 7 days (when it reaches roughly 70% strength), and apply full loads after 28 days. Keep the surface moist during the first week—curing is a chemical reaction, not just drying—because letting it dry out too fast leads to a weaker, more crack-prone slab. Cooler temperatures slow curing, while warm weather speeds it up.