Mix lime mortar for planters, walls, and edging with confidence. Estimate materials fast, reduce waste, and keep finishes breathable. Build stronger garden features with clean, simple planning.
| Scenario | Area (m²) | Thickness (mm) | Ratio | Waste | Dry Volume (m³) | Lime (kg) | Sand (kg) | Water (L) |
|---|---|---|---|---|---|---|---|---|
| Garden pointing | 10.00 | 10.0 | 1:3 | 10% | 0.1463 | 20.1 | 175.6 | 26 |
| Planter render | 8.00 | 12.0 | 1:2.5 | 12% | 0.1430 | 22.5 | 163.4 | 26 |
| Stone bedding | 6.00 | 15.0 | 1:3 | 8% | 0.1293 | 17.8 | 155.1 | 23 |
Lime mortar is valued in outdoor features because it remains permeable and flexible. In planters, edging, and low garden walls, moisture moves through joints and evaporates rather than being trapped. This behavior helps reduce frost damage and salt-related spalling in small-scale landscaping works. The calculator supports this approach by estimating a breathable binder-to-aggregate blend.
The starting point is wet mortar volume, calculated from coverage area and average thickness. For pointing, thickness often represents joint depth, while for rendering it reflects coat thickness. The dry factor then converts wet volume into the approximate dry materials volume needed for batching. A waste allowance is added to reflect uneven substrates, tool losses, and site handling.
A common garden ratio is 1:2.5 to 1:3 (lime:sand) by volume, balancing adhesion and finish. Finer sand can improve surface texture, while coarser sand can reduce shrinkage. Water demand varies by sand grading and temperature, so the water estimate should be treated as a starting range. Mix until cohesive, then adjust gradually for trowelability.
Bulk density settings translate calculated volumes into kilograms and bag counts. Hydrated lime typically has a much lower bulk density than sand, so small changes in density can shift bag estimates. If your supplier lists bag size or density differently, update the inputs to match. For sand, confirm whether you are buying dry, damp, or delivered bulk to avoid under-ordering.
Example: 10 m² pointing at 10 mm with 10% waste and a 1:3 ratio produces about 0.146 m³ of dry materials. With default densities, this is roughly 20 kg of lime and 176 kg of sand, plus about 26 L of water to begin. For small mixes, split the totals into repeatable buckets and keep proportions consistent across batches.
For many garden walls and edging, a 1:2.5 to 1:3 lime-to-sand ratio by volume works well. Increase sand slightly for firmer joints and reduce sand for smoother finishing, within practical limits.
Dry ingredients occupy more volume than the finished wet mortar because particles pack and voids change during mixing. The dry factor helps convert the installed wet volume into an estimate of dry materials needed.
Use 5–8% for clean, flat work and 10–15% for rough stone, deep joints, or messy access. Add more if you expect frequent re-tempering, long carry distances, or inconsistent joint widths.
No. Water demand depends on sand grading, moisture, temperature, and mixing method. Start with a lower amount than the estimate, then add small increments until the mortar is cohesive and workable.
Yes if your supplier provides different values, or if your sand is unusually light or heavy. Updating densities improves the kilogram and bag estimates, especially for lime where bulk density varies widely.
Yes. Use the render area and coat thickness as inputs, select an appropriate ratio, and include waste for texture and trowel losses. For multiple coats, calculate each coat thickness separately and add totals.
Divide the lime and sand volumes into repeatable parts using buckets or shovels, keeping the same ratio. Prepare several identical batches rather than one oversized mix, so workability stays consistent throughout placement.
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.