About Concrete Knowhow
Concrete Knowhow is a free tool suite for anyone who needs to estimate construction materials — homeowners tackling a weekend project, landscapers working up a bid, or contractors double-checking a supplier's quote. We cover concrete, gravel, mulch, topsoil, sand, and sod, and we give you the answer instantly, without a sign-up or a paywall.
How the calculators work
Every calculator on this site uses the same core geometry: multiply length × width × depth to get volume, then convert to the unit your supplier uses — cubic yards, tons, rolls, or bags. We apply material-specific density constants sourced from industry references and verified against published supplier data.
For example, our gravel calculator uses 1.5 t/yd³ for crushed stone and 1.4 t/yd³ for pea gravel — standard values drawn from ASTM gradation references. Our concrete bag yields (0.45 ft³ per 60 lb bag; 0.60 ft³ per 80 lb bag) match the manufacturer data sheets from the major ready-mix bag producers.
All calculations run entirely in your browser. Nothing is sent to a server.
Why we built this
Ordering the wrong amount of material is an expensive mistake. Order too little and you pay a second delivery fee — and deal with a color mismatch in your concrete pour. Order too much and you're hauling away a cubic yard of topsoil with nowhere to go. The math isn't complicated, but it's easy to get wrong when you're juggling inches, feet, cubic yards, and bag counts all at once.
We built Concrete Knowhow because we wanted a single, reliable place to do that math quickly — no ads blocking the inputs, no forced unit conversion in your head, no sign-up required.
Accuracy and methodology
Our reference values come from published industry sources:
- Concrete bag yields — manufacturer data sheets (60 lb bags yield 0.45 ft³; 80 lb bags yield 0.60 ft³). One cubic yard requires approximately 45 bags of 80 lb mix.
- Gravel densities — 1.4 t/yd³ for pea gravel; 1.5 t/yd³ for crushed stone. These are conservative mid-range values; actual density varies by material gradation and moisture.
- Sand densities — 1.35 t/yd³ for dry sand; 1.68 t/yd³ for wet-packed sand, per standard soil classification references.
- Topsoil settling — bulk topsoil compacts approximately 10–15% after delivery. Our calculator includes an optional settling allowance so you don't end up short of your target grade.
- Sod coverage — standard roll at 10 sq ft; pallet at 450 sq ft. Actual coverage varies by supplier and grass variety; always confirm before ordering.
We recommend adding a 5–10% waste buffer to all estimates. Real projects involve uneven subgrades, irregular shapes, and human error. The buffer costs far less than a second delivery.
Part of the Mr. Know-It-All network
Concrete Knowhow is part of Mr. Know-It-All, a small network of free reference tools. Our sister site, Tenant Knowhow, covers state-by-state renter rights with the actual statute cited on every page.
Feedback and corrections
If you find a calculation that seems off, or a material type we haven't covered, use our contact page to let us know. We take accuracy seriously and will investigate and update any reported discrepancy.