Calculator
Formula used
The calculator estimates replacement stone from area and thickness, then applies optional allowances.
- Vnet = A × t
- Vgross = Vnet × (1+w) × (1+o) × (1+c)
- Mass = Vgross × ρ
- Cost follows your pricing basis.
- Aface = (L+g) × (W+g)
- Nexact = A ÷ Aface
- Norder = ceil(Nexact × (1+w))
- Cost can be per block, volume, or ton.
A = area, t = thickness, ρ = density, and w/o/c are waste, overbreak, and compaction fractions.
How to use this calculator
- Pick a unit system that matches your site measurements.
- Select Bulk stone for aggregate or loose fill deliveries.
- Select Blocks for pavers, cobbles, or cut stone pieces.
- Enter the area and thickness/depth for the repair section.
- Set waste and optional allowances for your site conditions.
- Choose the pricing basis from your supplier quotation.
- Click Calculate, then export CSV or PDF as needed.
Example data table
| Scenario | Method | Inputs (summary) | Typical outputs (summary) |
|---|---|---|---|
| Walkway patch | Bulk stone | Area 48 m², thickness 75 mm, density 1600 kg/m³, waste 7% | Gross volume ≈ 3.86 m³, mass ≈ 6.18 t (plus pricing) |
| Courtyard pavers | Blocks | Area 35 m², 200×100×60 mm, joint 3 mm, waste 8% | Order count ≈ 1,944 blocks (rounded for waste) |
Example values are illustrative. Confirm supplier density and packaging.
Stone replacement estimating notes
1) Define the repair scope clearly
Start with measured repair area and the finished thickness you must restore on site. For irregular patches, break the surface into simple rectangles, then total the areas. Confirm whether the thickness includes bedding sand or base course, and record units. If the work includes edge restraints, haunching, or curb returns, measure those volumes separately and add them as distinct line items.
2) Choose realistic allowances
Waste covers cutting, breakage, and handling. For loose stone placed by skid-steer or excavator, 5–10% is common. For cut pieces with trimming, 8–15% is typical, especially where patterns require offcuts. Add overbreak when demolition cannot follow neat lines. Use a compaction factor when ordering loose material that settles after placement and vibration.
3) Use density to plan hauling
Density converts volume to weight for delivery and lifting planning. Crushed aggregates often range 1500–1900 kg/m³ (about 95–120 lb/ft³), depending on gradation and moisture. Confirm the supplier’s stated density or ticketed weight basis. If pricing is per ton, verify whether “ton” means metric or short ton before finalizing.
4) Align pricing with how you buy
Bulk materials are usually priced per volume or per ton, while pavers and cut stones are priced per piece. Use the same basis here to avoid rounding errors. For unit conversion, 1 m³ ≈ 1.308 yd³; reporting in the purchasing unit helps prevent order shortages. Check minimum load fees and partial-load surcharges, because they can dominate repair budgets.
5) Document outputs for approvals
Save the exported report with the project record. Keep notes on measurement dates, density source, and selected allowances, plus block size and joint gap assumptions. During execution, compare delivered quantities against the estimate and track waste causes. Updating these assumptions improves bid accuracy and material controls for future work.
FAQs
1) Should I use bulk stone or blocks mode?
Use bulk stone when material is delivered loose by volume or weight. Use blocks when you buy individual pavers, cobbles, or cut stones and need an order count.
2) What density should I enter?
Enter the supplier’s bulk density for the specific gradation. If unknown, request a product sheet or delivery ticket basis. Density varies with moisture and grading, so avoid guessing for final procurement.
3) How are waste, overbreak, and compaction applied?
The calculator multiplies the net volume by each allowance factor. Waste covers breakage and cutting. Overbreak adds extra removal volume. Compaction adjusts loose ordered material to match placed volume after settling.
4) Why do my results change after switching units?
The tool converts inputs to a single internal unit set, then reports back in your chosen units. If you switch units, re-enter values in the new units to avoid mixing m² with ft² or mm with inches.
5) How is block count calculated with joint gaps?
Each piece “covers” its face size plus the joint gap in both directions. The repair area is divided by that effective face area, then the calculator adds waste and rounds up to a whole number of blocks.
6) Can I estimate truckloads from the mass output?
Yes. Divide the estimated mass by the legal payload of your delivery vehicle. Confirm local limits and supplier truck types, because payload depends on axle ratings, moisture, and travel route.
7) What if my supplier quotes per cubic yard?
Select Imperial units for yd³ reporting, or keep Metric and convert. A quick check is 1 m³ ≈ 1.308 yd³. Matching the quotation unit reduces rounding and helps avoid under-ordering.