Step 1 — Choose Project Type
Select the project that best matches your work (slab, footing, column, driveway, stairs, pool, etc.). The form changes labels and the measurement guide so you only enter relevant dimensions.
Step 2 — Pick Units
Choose Imperial (ft/in) or Metric (m/cm). This ensures the calculator interprets your dimensions correctly and displays helpful unit labels in the 3D preview.
Step 3 — Enter Dimensions
Fill Length, Width (or Diameter for circular items) and Thickness (in inches or cm). For stairs, enter the number of steps as Length. Use decimals (e.g., 4.5 ft) for precision.
Step 4 — Waste & Optional Fields
Keep the default 10% waste for simple slabs. Use the field toggles to include/exclude things like labor, reinforcement, additives and PSI when in Advanced mode.
Formulas & Real Examples
Basic formulas the tool uses (you don't need to compute these manually):
- Rectangular slab: Volume (ft³) = Length × Width × Thickness(inches) ÷ 12 → divide ft³ by 27 → yd³.
- Circular slab: Area = π × (radius²); Volume = Area × thickness (ft) ÷ 27 → yd³.
- Column (cylinder): Volume = π × radius² × height (ft) ÷ 27 → yd³.
Worked Example — Patio
A 20 ft × 12 ft patio, 4" thick: 20 × 12 × (4 ÷ 12) = 80 ft³ → 80 ÷ 27 = 2.96 yd³ → +10% waste = 3.26 yd³.
Worked Example — Circular Slab
Diameter 10 ft, thickness 4": radius = 5 ft → area = π × 5² = 78.54 ft² → volume = 78.54 × (4 ÷ 12) = 26.18 ft³ → 0.97 yd³ → +10% = 1.07 yd³.
When to Use Advanced Mode
Advanced adds PSI selection, reinforcement type, labor rate, cement price and additives — use it for contractor-level estimates or bidding.
Ordering & Logistics
Most ready-mix trucks carry ~8–10 yd³. For >9 yd³ coordinate multiple trucks, staging, and consider a pump if access is constrained.
Reinforcement & Cover
Maintain 2–3 inches of concrete cover over rebar to prevent corrosion; wire mesh is often appropriate for slabs under 4" thickness.
Curing Best Practices
Keep slabs moist for 7 days minimum (longer for higher strength mixes); avoid heavy loading until 7 days, full strength ~28 days.
Interpreting Calculator Output
- Volume: Shows cubic yards, cubic feet and cubic meters with waste included.
- Materials: Bags of cement, sand and gravel estimates — bag counts are approximate for bagged mixes.
- Costs: Itemized materials and labor estimate; adjust labor rate and cement price in Advanced for local accuracy.
- 3D View: Visual preview that helps verify proportions — rotate, zoom and export images or PDF report.
Quick Troubleshooting
- If the ad placeholder blocks layout, ignore it — calculator inputs and results are unaffected.
- Empty or invalid numbers will trigger a prompt — ensure positive numeric values.
- If the 3D view looks off, check that units and length/width fields match the selected project type (e.g., circular uses Width as diameter).
Practical Checklists
Before You Order
- Confirm measurements on site (measure twice)
- Decide on finish type and reinforcement
- Confirm truck access and pump needs
At the Pour
- Have tools, screed, trowels and bull float ready
- Assign crew roles and pace the pour
- Use control joints and monitor slump
Exporting & Sharing
After calculating you can:
- Export a polished PDF report (includes summary, materials table, costs and regional comparisons).
- Save projects locally in your browser for later comparison.
- Copy all results to clipboard to paste into emails or supplier forms.
Extra Resources
See the FAQ for common questions, or open the Blog for case studies and real pour stories. Contact us for feature requests or local pricing help.