About CementCalcs
CementCalcs is an independent project with one goal: to gather the everyday calculations homeowners, DIYers and small contractors reach for when concrete is going in — volume & material, driveways, patios & slabs, stamped & decorative, sidewalks & steps, and repair & leveling — in one focused, free, no-signup hub with transparent formulas, so you can budget a concrete project and sanity-check a contractor’s quote.
Who is behind it
Author and curator
To be clear about credentials: I am the author and curator of this site — not a licensed concrete contractor, a structural or civil engineer, or an ACI-certified finisher, and I claim no trade credential. What I bring is relevant and real: building deterministic online calculators (open-source Python projects) and electronic-engineering training, i.e. rigor on the quantity and cost arithmetic. That is what it takes to curate a hub of calculators: transparent method, correct formulas, cited conventions and worked examples.
Our principle: transparent & durably correct
Every calculator shows its formula, a worked example and a reference table. The tools rest only on timeless concrete math (volume = area × (thickness ÷ 12); cubic yards = cu ft ÷ 27; bags = ceil(cu ft ÷ bag yield); ready-mix cost = yd³ × your $/yd³ + delivery; slab/driveway cost = area × your $/sq ft + sub-base + rebar + add-ons, ×(1 + contingency); rebar linear ft from grid spacing; gravel, tube and step volumes by geometry) and stable conventions (1 yd³ = 27 ft³; bag yields 40/60/80 lb; slab thickness bands; rebar spacing; sub-base depth; waste %). There are deliberately no ready-mix or labor prices, no regional cost indexes, no product catalog and no contractor directory — cost tools use the prices you enter — so the results stay valid over time.
Correctness is checked against known reference values (see the methodology and the numeric self-check). The formulas and their basis are documented under Sources & formulas. All results are planning estimates and material-quantity guides: get itemized written quotes from licensed, insured concrete contractors, confirm yield on your product’s bag/spec sheet, and order a little extra (5–10%) for spillage and uneven subgrade. Structural, geotechnical and load-bearing design is out of scope and is for a licensed engineer. Questions? Use the contact page.