Calculator Inputs
Example Data Table
These sample values show how a slab estimate is structured.
| Scenario | Shape | Dimensions | Waste | Unit Price | Fees |
|---|---|---|---|---|---|
| Patio Slab | Slab | 6 m × 4 m × 0.12 m | 10% | $140 per m³ | $60 delivery |
| Strip Footing | Footing | 12 m × 0.5 m × 0.3 m | 8% | $150 per m³ | $0 pump |
| Column Set | Cylinder | 0.35 m diameter × 3 m height (×6) | 12% | $155 per m³ | $120 pump |
Formula Used
The calculator first finds concrete volume, then applies waste, then totals costs.
- Slab: Volume = Length × Width × Thickness
- Footing/Rectangular Column: Volume = Length × Width × Height
- Wall: Volume = Length × Height × Thickness
- Cylindrical Column: Volume = π × (Diameter ÷ 2)² × Height
- Waste: Adjusted Volume = Base Volume × (1 + Waste% ÷ 100)
- Material: Material Cost = Adjusted Volume × Unit Price
- Labor: Labor Cost = Adjusted Volume × Labor Rate
- Total: Total = (Subtotal − Discount) + Tax
For imperial inputs, feet and inches convert to metric internally, then display as cubic yards.
How to Use This Calculator
- Select Metric or Imperial, then choose the shape.
- Enter dimensions and quantity for repeated pours.
- Set waste, unit price, and labor rate per volume unit.
- Add delivery, pumping, and any additional fees.
- Optionally include reinforcement allowance, tax, and discount.
- Press Calculate to see totals, then export CSV or PDF.
Professional Guide: Estimating Concrete Cost
1) Start with the correct pour geometry
Cost accuracy begins with volume. For a slab, measure length and width at the finished edges, then confirm thickness from drawings. For footings and walls, verify depth and thickness after formwork is set, because small dimensional changes multiply quickly over long runs.
2) Convert dimensions into an orderable volume
This calculator converts your dimensions into a single volume figure and then displays it in the unit you selected. Ordering is typically based on total required volume rather than area, so the volume step is where most estimating errors appear.
If you have partial-depth thickening, steps, or haunches, estimate them as separate shapes and add the volumes together. This approach matches how concrete is commonly ordered and helps you justify quantities during reviews.
3) Apply a realistic waste allowance
Waste covers spillage, pump priming, uneven subgrade, and over-excavation. Many crews use 5%–15% depending on access and crew experience. Tight residential sites and hand-finishing often need more allowance than open, truck-accessible placements.
4) Separate material pricing from site labor
Unit price represents delivered concrete, but labor reflects placing, vibrating, screeding, finishing, and curing protection. Breaking these into separate inputs helps you compare vendor quotes without losing sight of crew productivity and scheduling constraints.
5) Include pumping, delivery, and logistics fees
Pump charges can exceed the cost of several cubic meters on small pours. Delivery fees, short-load penalties, and after-hours surcharges also impact the total. Use the fee fields to capture these items so your estimate matches real invoices.
Logistics also affect placement rate: long wheelbarrow runs, crane buckets, or limited truck staging can slow delivery and increase labor. Capturing these realities as explicit costs keeps your estimate aligned with site constraints.
6) Account for reinforcement and embedded items
Rebar, mesh, chairs, dowels, and embeds add cost and labor. The reinforcement allowance percentage provides a fast way to include these items when detailed takeoffs are not yet complete, especially during early budgeting or concept stages.
7) Model taxes, discounts, and multiple pours
Some projects apply tax to the whole package, while others tax only certain line items. Add a discount to reflect negotiated pricing, and use the pour count to understand cash flow per placement. Extra per-pour costs help represent repeated mobilization.
8) Review outputs and export for records
Compare base volume versus waste-adjusted volume, then review the cost breakdown to see which drivers dominate your total. Export CSV for estimating spreadsheets and PDF for approvals, submittals, or daily pour documentation.
FAQs
1) Should I order based on base volume or waste-adjusted volume?
Order using the waste-adjusted volume. Base volume describes geometry, but waste covers placement losses and field variability. It reduces the risk of running short and paying expensive emergency load fees.
2) What waste percentage is reasonable for most jobs?
Many estimates start at 10%. Use 5% for simple, accessible pours with good formwork, and 12%–15% for tight access, pumping, uneven subgrade, or complex shapes.
3) Why does pumping change the total so much on small pours?
Pump mobilization is often a fixed charge. When volume is low, that fixed amount becomes a larger percentage of the project. Enter pump fees separately to see the true impact.
4) How do I estimate labor if I only have an hourly crew cost?
Convert to a rate per volume using expected productivity. For example, if a crew places 8 m³ per hour and costs $200 per hour, labor is $25 per m³. Adjust for finishing complexity.
5) Does the reinforcement allowance replace a detailed rebar takeoff?
No. It is a budgeting shortcut. Use it when drawings are early or time is limited, then replace it with a rebar and embeds takeoff before final pricing and procurement.
6) When should I use the “extra cost per additional pour” field?
Use it when each pour requires repeated setup, travel, or equipment re-mobilization. It’s helpful for phased slabs, staged footings, or work split across multiple days.
7) Can I switch between metric and imperial without re-entering values?
Switching changes labels and internal conversions, but it will not automatically convert your typed numbers. For best results, choose the unit system first, then enter measurements and pricing in that system.
Build with clarity, verify quantities, and reduce surprises always.