Calculator Inputs
Example Data Table
| Scenario | Area (m²) | Thickness (mm) | Mix | Waste (%) | Wet Volume (m³) | Cement (bags) | Sand (m³) |
|---|---|---|---|---|---|---|---|
| Apartment room | 24.00 | 50 | 1:4 | 7 | 1.200 | ~11.6 | ~1.95 |
| Small corridor | 12.50 | 40 | 1:5 | 5 | 0.500 | ~4.2 | ~0.93 |
| Workshop slab | 60.00 | 60 | 1:3 | 10 | 3.600 | ~44.0 | ~5.05 |
Example outputs are rounded for illustration and may differ from your inputs.
Formula Used
- Area (m²) = Length × Width, or entered directly.
- Thickness (m) = Thickness(mm) ÷ 1000.
- Wet volume (m³) = Area × Thickness.
- Wet volume with waste = Wet volume × (1 + Waste% ÷ 100).
- Dry volume = Wet volume with waste × Dry factor.
- Total parts = 1 + sand part (from 1:x).
- Cement volume = Dry volume × (1 ÷ total parts).
- Sand volume = Dry volume × (sand part ÷ total parts).
- Cement kg = Cement volume × Cement density.
- Bags = Cement kg ÷ Bag weight.
- Water liters ≈ Cement kg × Water–cement ratio.
How to Use This Calculator
- Enter floor length and width, or type the total area.
- Set screed thickness and a realistic waste allowance.
- Select a cement-to-sand mix ratio that matches your spec.
- Keep the dry factor and cement density at typical values unless you have better data.
- Optional: add unit prices to estimate total cost quickly.
- Press Calculate to see results above the form.
- Use Download CSV or Download PDF for records.
Professional Notes
Scope and Measurement Control
Accurate screed takeoff starts with consistent measurement. Verify finished levels, then confirm the net floor area after subtracting large openings. Thickness should reflect design tolerances and substrate variation, not only nominal specification. When areas are irregular, break the slab into rectangles and sum totals. This calculator accepts either area directly or length and width, reducing input errors on site. Record units to avoid conversion mistakes always.
Thickness, Volume, and Waste Planning
Screed volume depends on area and thickness, converted from millimeters to meters. Wet volume represents placed material, while waste covers spills, edge trimming, and local depressions. Typical waste allowances range from five to ten percent, but complex layouts may need more. The results show wet volume and wet volume with waste so procurement can match practical delivery and placement conditions. Round up deliveries to batch sizes.
Mix Ratio and Dry Volume Factor
Sand–cement screeds are proportioned by volume, commonly one to four or one to five, depending on strength and finish requirements. Dry volume is higher than placed volume because voids in aggregates and bulking must be accounted for. A dry factor of about 1.25 to 1.40 is often used for planning. The calculator splits dry volume into cement and sand quantities for consistent batching.
Cement, Bags, and Water Estimation
Cement quantity is computed from cement volume and an assumed bulk density, then converted into bags using the selected bag weight. These estimates support ordering and storage decisions, especially where deliveries are constrained. Water demand is approximated from the water–cement ratio, giving a practical mixing target. Always adjust water to achieve workability without overwatering, which can reduce strength and increase shrinkage. Consider sand moisture changes.
Costing, Productivity, and Quality Checks
Unit rates convert quantities into a quick budget. Enter cement cost per bag, sand cost per cubic meter, labor cost per square meter, and any additive allowance. The total helps compare options such as different thicknesses or mixes. For quality, confirm surface preparation, bonding or membranes, and curing method. Good curing reduces cracking, dusting, and premature failure in service environments. Document assumptions to support approvals internally.
FAQs
What thickness should I use for screed?
Use the project specification first. If none exists, base thickness on leveling needs, loading, and finish type. Thinner layers need better substrate flatness and bonding control.
Why is a dry volume factor included?
Dry ingredients occupy more volume than the placed screed due to voids and bulking. The factor converts placed volume into purchasable cement and sand quantities for planning.
How do I choose a mix ratio?
Stronger, wear‑resistant screeds often use richer mixes like 1:3 or 1:4. Leaner mixes like 1:5 suit light duty. Confirm with structural and finish requirements.
Does the water estimate replace field adjustment?
No. It provides an initial target only. Adjust water for sand moisture, temperature, and workability, and avoid overwatering to reduce shrinkage and strength loss.
Can I estimate cost with different currencies?
Yes. Enter unit prices in any currency, and the calculator keeps the same unit throughout. Ensure all price inputs use the same currency to avoid confusion.
How accurate are the material totals?
They are planning estimates. Accuracy depends on measurement quality, waste control, and local material properties. Always verify with site trials and supplier packaging details.