Concrete volume & bags
Choose the shape that matches your pour. Steps use a triangular prism approximation of total rise and run.
Concrete results
Calculation steps: input dimensions are converted internally to feet, the base volume 0.00 ft³ is computed, then the waste allowance 10% is applied to get 0.00 ft³. Results in yd³ and m³ use 1 yd³ = 27 ft³ and 1 ft³ ≈ 0.0283 m³.
Bag counts (rounded up)
Estimates only. Verify mix design, compaction, and true bag yield with your supplier before ordering.
How to use this calculator
Select the material tab first, then enter your project dimensions using whichever unit system is most comfortable. Thickness, depth, tread, and riser inputs switch between inches and centimetres automatically as you toggle systems.
Waste allowance helps you plan for offcuts, trench over-excavation, spillage, and compaction. Increase it for irregular layouts or when you rely on ready-mix trucks with minimum load requirements.
Always stake out, double-check elevations, and verify local code requirements for concrete strength, reinforcement, and frost protection.
Material presets
- Concrete bags: nominal yields of 0.30, 0.375, 0.45, and 0.60 cubic feet for 40/50/60/80 lb products.
- Gravel densities: 1.30–1.50 tons per cubic yard (loose bulk). Adjust if ordering washed stone or compacted road base.
- Mulch bags: standard 2 ft³ and 3 ft³ sizes with no compaction factor.
Edit /common/data/materials_presets.json if your supplier publishes different bag yields or bulk densities.
FAQ
How accurate are these concrete, gravel, and mulch estimates?
Calculations assume right angles, uniform depth, and the waste allowance you choose. Site conditions such as subgrade compaction, slopes, bracing thickness, and moisture content can change the real quantity required, so treat the output as a planning baseline and confirm with your contractor or supplier.
What bag sizes and material presets does this calculator use?
Concrete bag counts use nominal 40, 50, 60, and 80 lb yields; mulch defaults to 2 and 3 cubic foot bags; gravel densities range from 1.30 to 1.50 tons per cubic yard. Update the presets file if your supplier quotes different values.
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