Stone Masonry Calculator
Estimate stone volume, mortar volume, and labour-days for a stone masonry wall, with separate factors for random rubble and coursed bond types.
How this works
Wall volume is the wall face area times thickness; the bond type determines what fraction of that volume is stone vs mortar:
wallVol = wallArea × wallThickness (m³)
stoneVol = wallVol × stoneFraction[bondType] (m³)
mortarVol = wallVol × (1 − stoneFraction[bondType]) (m³)
labourDays = wallArea × labourPerM2[bondType] (days)Random rubble: stone fraction 0.70, labour 0.4 mason-days/m². Coursed: stone fraction 0.75, labour 0.6 mason-days/m². Coursed work uses less mortar but takes more time per square metre because each stone is squared first.
Worked example
A wall of 50 m² face area at 0.40 m thickness, built in random rubble:
- Wall volume = 50 × 0.40 = 20.00 m³
- Stone (70%) = 20 × 0.70 = 14.00 m³
- Mortar (30%) = 20 × 0.30 = 6.00 m³
- Labour = 50 × 0.4 = 20 mason-days
Switch to coursed and the same wall needs 15.00 m³ of stone, 5.00 m³ of mortar, and 30 mason-days — fewer mortar deliveries but two extra weeks of skilled labour.
Sources
- IS 1597 (Part 1 & 2) — Code of practice for construction of stone masonry (rubble and ashlar)
- Typical stone-fraction and labour rates from rural Nepal / India masonry practice
FAQ
What is the difference between random-rubble and coursed stone masonry?
Random-rubble masonry uses irregular, undressed stones laid without horizontal courses — quick to build, lower stone proportion (around 70%), more mortar (around 30%). Coursed masonry uses roughly squared stones laid in continuous horizontal courses, giving a tidier face and higher stone proportion (around 75%), less mortar (around 25%). Coursed stonework is slower but stronger and more weather-tight.
Why does random-rubble use more mortar?
Irregular stone shapes leave large gaps between courses that have to be packed with mortar plus small chip stones (called dabs or galets). Coursed stones are squared off so the joints are uniform and thinner, typically 12 to 20 mm against 25 to 40 mm for random rubble.
How is the labour-day estimate derived?
0.4 mason-days per m² for random rubble and 0.6 mason-days per m² for coursed are typical figures from rural and small-town stonework in Nepal and India. They include a single mason plus one or two helpers — adjust upward for tight site access or downward for experienced crews working on standard sections.
What stone density should I assume?
Most Indian / Nepali masonry stone (granite, basalt, sandstone, quartzite) ranges from 2,400 to 2,800 kg/m³. To convert the calculator's stone volume to weight for transport planning, multiply by your local stone density. Soft sandstones can drop to 2,000 kg/m³; dense basalts can reach 3,000.
What mortar mix should I pair with stone masonry?
Cement:sand 1:6 is the modern default for non-load-bearing or single-storey construction. 1:5 or 1:4 is used for load-bearing or two-storey walls. For breathable repair work on heritage stone walls, switch to a lime-sand mortar (1:3 hydrated lime to sand). Always match the mortar to the stone hardness — a lime mortar is essential for soft sandstone or limestone.
Should I add wastage to the stone order?
Yes. Plan for 10 to 15 percent wastage from breakage, off-cuts, and rejected pieces. Pad more for a remote site, irregular shapes (e.g. arch voussoirs), or when working with a single quarry where you cannot return rejected stones.