Plan smarter. Build with confidence.

Know your materials, costs, and risks before you break ground

HomeBuild Atlas pairs free construction calculators with standards-based guides so homeowners, DIYers, and contractors can estimate concrete, gravel, excavation, and drainage projects accurately - and know when a job needs a professional.

Browse the calculators Read the guides

✓ Free, no signup ✓ Every formula documented ✓ Worked examples included ✓ Downloadable PDF reports ✓ Safety & professional guidance

Calculators

Eight planning tools, every formula documented

Each calculator shows its math, includes a worked example you can verify by hand, and explains the waste, compaction, and swell factors that separate a good estimate from a short order.

▦Concrete CalculatorCubic yards, bags, weight, and ready-mix order size for slabs, patios, and driveways.Calculate concrete → ▩Gravel & AggregateTons and truckloads with compaction and density corrections for six material types.Calculate gravel → ◤Excavation & TrenchDig volume, soil swell by soil type, and dump-truck loads for haul-away planning.Calculate excavation → ⚏French Drain PlannerStone, pipe, fabric, and the elevation drop your slope needs - a full materials list.Plan a drain → ▲Slope & GradeConvert percent, degrees, and ratios; get the fall in inches over any distance.Calculate slope → ✿Mulch & TopsoilCubic yards and bag counts for mulch, topsoil, and compost, with the bags-vs-bulk break-even.Calculate mulch → ▮Fence Post ConcreteBags per post and per fence line from hole size and depth, with sizing rules by fence height.Calculate posts → ▣Cubic YardsAny shape to cubic yards, cubic feet, cubic meters, and tons; the first step of every estimate.Calculate volume → →All ToolsSee the full directory of calculators and what each one is designed for.View directory →

Browse by topic

Four project hubs, start to finish

Each hub collects the calculators, planning guides, and current 2026 cost references for one kind of project, in the order you will need them.

HubConcrete ProjectsSlabs, footings, and fence posts: volume math, base prep, bags vs. ready-mix, and current per-yard prices.Explore concrete → HubGravel & AggregateDriveways, bases, and paths: tonnage conversions, layer construction, and per-ton pricing.Explore gravel → HubExcavation & DirtDigging, grading, and hauling: soil swell, truckload planning, and contractor rates.Explore excavation → HubDrainage & SlopeFrench drains, grading, and wet yards: specifications, failure modes, and installed costs.Explore drainage →

Why HomeBuild Atlas

Estimates you can check, not black boxes

"We show the math, explain the assumptions, and tell you where the calculator stops."

Every formula shown

No hidden math. Each tool documents its formula and a worked example so you can verify the result before spending money on materials.

Standards-based

Guides are developed against published industry references - concrete practice, OSHA excavation rules, aggregate standards, residential code - and every guide tells you plainly when a project needs a licensed pro.

Real-world corrections

Waste factors, soil swell, compaction, and density conversions are built in - the details that make the difference between an estimate and a guess.

Actionable next steps

Every result connects to the guide, checklist, or safety information for that project - and tells you plainly when the next step is a licensed professional, not a bigger order.

How it works

Pick the tool that matches your project - concrete, gravel, digging, drainage, or grading.
Enter dimensions in feet and inches; results update instantly as you type.
Check the math against the documented formula and worked example.
Save your numbers - download a PDF report of your inputs and results to share with suppliers and contractors, and read the linked guide to plan the job.

Featured guides

Start with the questions every project asks