Overview
Concrete and masonry work fails most often not from bad technique but from bad math — ordering too little mid-pour, or too much and paying for waste. This handbook walks through the material calculations for the most common concrete and masonry jobs, from a basic slab to columns, stairs, and block walls, ending with the mortar, grout, and thinset needed to finish the job.
Work through the sections in the order you'd actually encounter them on a project: rough volume and weight first, then shape-specific calculations, then the finishing materials that bond everything together.
Step 1: Estimate Base Volume and Weight
Every concrete job starts with a basic volume-to-weight relationship. Concrete weighs roughly 4,050 pounds per cubic yard, a number you'll need for both delivery planning and structural load estimates.
The Cement Calculator gives you the base material volume for a slab or footing, and the Concrete Weight Calculator converts that volume into total weight — always add a 5–10% waste allowance on top of the raw calculated volume before finalizing an order.
Step 2: Calculate Concrete for Columns and Sonotubes
Columns and cylindrical footings (poured in sonotube forms) use different volume formulas depending on shape — round columns and sonotubes use π × radius² × height, while rectangular columns use straightforward length × width × height.
The Concrete Column Calculator handles both shapes, and the Concrete Estimator - Tube is purpose-built for sonotube footings, letting you total volume across multiple footings of the same diameter and depth at once — common when pouring several deck or fence posts in one order.
Step 3: Calculate Concrete Stairs
Stairs don't follow a simple volume formula because their profile is stepped rather than a single rectangular or cylindrical shape — the total volume is the sum of each individual step's tread, riser, and width dimensions.
The Concrete Stairs Calculator sums this across all steps automatically, which avoids the common error of estimating stair volume as if it were a solid ramp.
Step 4: Size Fence Post and Footing Holes
Post and footing holes are almost always cylindrical, so their volume follows π × radius² × depth — the most common measurement error here is using diameter instead of radius, which overstates the required volume by 4x.
The Hole Volume Calculator takes diameter and depth directly, applying the radius conversion internally so you don't have to do it by hand.
Step 5: Build Block Walls and Calculate Core Fill
Concrete block (CMU) walls require two separate calculations: the number of blocks needed for the wall's footprint, and — if the design calls for reinforced or fully-grouted cells — the volume of grout or concrete needed to fill the hollow block cores.
The Concrete Block Calculator sizes the wall itself, and the Concrete Block Fill Calculator calculates fill volume, including support for partial-fill patterns where only reinforced cells are filled.
Step 6: Finish with Mortar, Thinset, and Grout
Mortar, thinset, and grout are all cement-based, but they aren't interchangeable — mortar bonds masonry units in structural joints, thinset adheres tile to a substrate, and grout fills the joints between set tiles (or, as in Step 5, hollow block cores).
Use the Mortar Calculator for block and brick joints, the Thinset Calculator for tile setting, and the Grout Calculator for joint and gap filling — a typical tile job needs both thinset and grout, applied in that order.
Key Terms
- Waste allowance — the extra percentage (typically 5–10%) added to a calculated material volume to cover spillage and irregular site conditions
- Cubic yard — the standard unit for ordering ready-mix concrete, equal to 27 cubic feet
- CMU (concrete masonry unit) — a standardized hollow concrete block used in wall construction
- Core fill — grout or concrete poured into the hollow cavities of a concrete block, often used to embed reinforcing rebar
- Sonotube — a cylindrical cardboard form used to pour concrete footings and piers
- Cure time — the period during which poured concrete gains strength, affected significantly by temperature and moisture
- Thinset — a cement-based adhesive mortar used to bond tile to a substrate