About us
We build free, accurate construction calculators with the depth a working contractor needs and the clarity a homeowner deserves.
Calc/concrete started in 2008 as a single spreadsheet shared between estimators on commercial pours. Today it's a free online toolkit covering volume, weight, bag count, mix design, and curing — everything required to plan a residential or light commercial concrete job from sketch to delivery.
We don't sell concrete. We don't take affiliate cuts on bag links. We make the calculator free because most published "calculators" are wrong about bag yields, ignore waste factors, or hide their math behind a paywall — and a homeowner who comes up short on a one-truck pour pays for it twice.
Who we are
The site is maintained by a small team of working concrete estimators and a software engineer. Mix data comes from published industry references; bag yields are cross-checked against the major US manufacturers. Updates ship every quarter.
How accurate are the numbers?
The geometry math is exact. The bag and truck counts use industry-standard yields (0.60 ft³ for an 80-lb bag, 9 yd³ for a standard ready-mix truck) — within a percent or two of any major brand. Always order 5–10% extra for waste; the calculator includes that on the bag count by default and tells you when it does.