Concrete & Masonry Calculators — Bags, Rebar Grids & Footings

Planning a Concrete Project

Concrete work is unforgiving of guesswork — ordering short means a delayed pour with a partially cured joint, and ordering heavy wastes money on a job where bagged mix isn't cheap. The three calculators in this category cover the most common residential concrete tasks: slabs and pads (Concrete Bags), reinforcement for those slabs (Rebar Grids), and continuous footings for foundations, walls, or posts (Footings).

How These Calculators Work Together

A typical small pour starts with the Footings calculator if you're setting posts or a foundation wall, or the Concrete Bags calculator for a flat slab like a patio or walkway. If the slab needs reinforcement — common for driveways, larger patios, or anything bearing significant load — the Rebar Grid calculator sizes the steel grid separately, since rebar and concrete are bought from different suppliers and priced independently.

Frequently Asked Questions

Should I use pre-mix bags or ready-mix delivery?

Bagged pre-mix is practical for smaller pours — generally up to a cubic yard or two before hand-mixing becomes impractically slow. Larger pours are usually more cost-effective and structurally consistent with a ready-mix truck, since it's mixed to a controlled ratio and poured all at once rather than in dozens of small batches.

What PSI rating do I need?

Standard bagged concrete mix is typically rated around 4,000 PSI at 28 days, which is suitable for most residential slabs, footings, and sidewalks. Structural applications like foundation walls or heavily loaded footings may call for a higher-strength mix — check your project's engineering spec or local code.