Enter slab dimensions and thickness to size your concrete overlay quickly today. Include waste, weight, trucks, and costs to order confidently on-site every time.
| Scenario | Shape | Dimensions | Thickness | Waste | Estimated Volume (m³) |
|---|---|---|---|---|---|
| Walkway refresh | Rectangle | 6 m × 1.2 m | 40 mm | 8% | 0.311 |
| Patio skim | Rectangle | 4.5 m × 3 m | 50 mm | 10% | 0.743 |
| Round pad | Circle | Diameter 3 m | 60 mm | 12% | 0.475 |
Area
Area = Length × WidthArea = π × (Diameter ÷ 2)²Volume
V_net = Area × ThicknessV_total = V_net × (1 + Waste% ÷ 100)Weight (optional estimate): Weight = V_total × Density
An overlay calculation sets ordering, delivery timing, and placement manpower. Volume drives the number of ready-mix loads, pump setup decisions, and finishing windows. A small under-order can cause cold joints, while a large over-order raises disposal and cleanup costs on active job sites.
Thin resurfacers may start near 10–25 mm, while bonded structural overlays commonly range 50–100 mm depending on design. Thickness should reflect substrate profile, drainage requirements, and reinforcement details. Use measured spot depths and average them; do not rely on nominal drawings alone.
Scarification, shot blasting, and crack repairs change the effective thickness and can increase consumption. If the base has ruts or spalls, the overlay fills them first. Treat patched zones as extra thickness areas or increase waste so the estimate reflects real substrate absorption and profile.
Waste accounts for edge losses, chute leftovers, pump priming, and minor form leaks. For clean access and consistent slabs, 5–8% is often reasonable. Tight access, hand placement, or uneven grades can push waste to 10–15%. Document assumptions to defend procurement decisions.
Field teams think in millimeters, inches, feet, and yards, while suppliers often quote cubic meters or cubic yards. Converting thickness to meters before multiplying by area avoids hidden mistakes. This calculator reports m³, ft³, and yd³ so ordering matches local supplier tickets.
Concrete density near 2400 kg/m³ provides a workable planning value. Weight helps verify if temporary platforms, hoists, or elevated decks can handle staged material. It also supports logistics for bagged additives, reinforcement placement, and safe material handling when access routes are constrained.
Dividing total volume by truck capacity estimates the number of loads and helps schedule deliveries. Align arrival spacing with crew output, finishing type, and ambient conditions. Faster placement reduces joint risk, but crowding trucks can create site congestion and safety issues during discharge.
When you enter a unit price, the calculator provides an immediate budget check for bidding and change orders. Exporting to CSV or PDF creates a traceable record of inputs, waste, and assumptions. This improves coordination between procurement, supervision, and accounting teams.
Use volume with waste for ordering ready-mix. Net volume is a theoretical minimum and rarely matches field realities like edge loss, pump priming, and uneven substrates.
Many straightforward overlays use 5–12% waste. Increase toward 15% for rough substrates, hand placement, tight access, or multiple small pours with more cleanup losses.
Take several spot-depth readings across the area, including low points and patched zones, then use a practical average. For sloped surfaces, confirm depth at both ends.
Grinding, scarifying, and repair work can expose voids and depressions that the overlay must fill first. That effectively increases thickness and material demand beyond nominal plans.
Use 2400 kg/m³ for normal-weight concrete planning. Lightweight mixes can be lower, and specialty mixes may differ. If your supplier provides a mix density, use that value.
It is a planning estimate based on total volume and the truck capacity you enter. Confirm local truck sizes and consider partial loads, minimum order policies, and site access restrictions.
Approximate irregular areas by splitting them into rectangles and circles, then add the volumes. Alternatively, use a measured total area and an average thickness, then apply waste.
Measure carefully, add waste, and order concrete confidently today.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.