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Concrete Mix Calculator

The right mix for the job, and exactly how much of it.

Ordering concrete has two failure modes: the wrong amount (a short pour is a cold joint and a weak slab) and the wrong mix (a non-air-entrained driveway in Kansas scales apart in three winters). This calculator converts your dimensions to yards and bags with the 10% over-order rule, then specs the mix strength and air entrainment the application actually needs.

Why people use this

Anyone calling a ready-mix plant for the first time uses this: the plant asks "how many yards and what mix?" and this answers both. It is also the settle-the-argument tool for whether a job is a bagged-mix Saturday or a truck delivery.

How it works

1. Pick the job: footing, interior slab, driveway, patio, or specialty.
2. Enter length, width, and thickness — the calculator converts square feet to cubic yards (1 yd³ = 81 sq ft at 4 inches).
3. Read the recommended PSI, whether you need air entrainment, and the order quantity with 10% extra.
4. Compare ready-mix versus 80-lb bags with editable local prices.

Common questions

How many square feet does a yard of concrete cover?

One cubic yard covers 81 sq ft at 4 inches thick, 108 sq ft at 3 inches, or 54 sq ft at 6 inches. A 24×12 driveway at 4 inches is 288 sq ft, which needs 3.56 yards — order 4.

What PSI concrete do I need for a driveway?

3,500–4,000 psi with 5–7% air entrainment in any climate that freezes. Interior slabs can run 3,000–3,500 psi without air. The mix design matters as much as thickness for how long the slab lasts.

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