Inputs
Example data table
| Scenario | Total wall area | Openings area | Coats | Coverage | Waste | Estimated liters |
|---|---|---|---|---|---|---|
| Interior plaster, moderate porosity | 120 m² | 18 m² | 2 | 6.0 m²/L | 10% | ~44–48 L |
| Exterior masonry, rough texture | 200 m² | 20 m² | 3 | 5.0 m²/L | 12% | ~150–165 L |
| Smooth render, efficient rolling | 85 m² | 10 m² | 2 | 7.0 m²/L | 8% | ~23–26 L |
Formula used
The calculator estimates required limewash by adjusting net wall area for surface conditions, applying waste, then dividing by coverage.
Base Area = Net Area × Texture Multiplier × Absorption Multiplier
Effective Area = Base Area × (1 + Waste% / 100)
Required Liters = (Effective Area × Coats) ÷ Coverage (m²/L)
If you use ft²/gal for coverage, it is converted internally to an equivalent m²/L.
How to use this calculator
- Measure total wall area, then estimate openings to deduct.
- Select units for area and for the product’s coverage rate.
- Choose coats and enter coverage from the manufacturer datasheet.
- Set texture and absorption multipliers to match your surface.
- Add a waste percentage for mixing losses and touch-ups.
- Optional: enter bucket size and price for procurement planning.
- Click Calculate to view liters, buckets, and cost instantly.
Download options
After you calculate, use the Download CSV and Download PDF buttons in the results panel to save your inputs and outputs.
Limewash coverage planning
This calculator turns field measurements into a clear materials plan. It combines net wall area, coats, and coverage with practical multipliers for texture and absorption, then adds an optional waste allowance. Use it to order buckets confidently, reduce stoppages, and keep your finish consistent.
1) Start with accurate wall area
Measure each elevation and sum the gross wall area, then deduct large openings such as doors and windows. Net wall area is the strongest driver of quantity. For fast checks, compare your net figure to room plans, façade grids, or takeoff sheets to reduce rework later.
2) Use realistic coverage per coat
Coverage is typically stated for one coat and varies by product and dilution. Many sites see roughly 4–8 m²/L on mineral substrates. Smooth render trends higher, while rough brick or block trends lower. Always match the datasheet test surface as closely as possible.
3) Adjust for texture and absorption
Limewash is sensitive to surface profile and porosity. A light texture multiplier of 1.10 adds 10% demand. Highly textured masonry can justify 1.20–1.30. Porous lime plaster and soft brick may require 1.10–1.30 absorption factors, especially for the first coat.
4) Set coats and waste allowance
Two coats are common for uniform color, while three coats can improve depth and exterior durability. Waste of 5–15% covers mixing losses, tray residue, overlaps, and touch-ups at edges and details. If multiple colors or short runs are planned, increase waste slightly.
5) Convert to buckets and cost
Procurement works best in whole containers. After liters are calculated, divide by bucket size and round up to avoid mid-job shortages. If you enter a bucket price, the calculator returns an immediate material budget that supports estimates, bid comparisons, and purchase approvals.
FAQs
1) Should I deduct small penetrations?
Usually no. Deduct doors, windows, and large voids. Small items are typically covered by your waste percentage and normal overlap at edges.
2) Which coverage value should I trust?
Start with the manufacturer’s stated coverage for one coat. Then validate using a small test area on your actual substrate and adjust texture or absorption multipliers if needed.
3) What multipliers are typical?
Use 1.00 for smooth sealed surfaces, 1.10 for moderate texture or porosity, and 1.20–1.30 for very rough or highly absorbent masonry. Confirm with a site patch test.
4) How many coats are common?
Two coats often suit interiors. Exteriors, darker tones, or uneven backgrounds may benefit from three coats. Use the coat input to compare scenarios quickly.
5) Why add waste?
Waste covers mixing loss, splatter, roller loading, container residue, and touch-ups. It also buffers measurement uncertainty. Many projects plan 5–15% depending on complexity.
6) Can I input ft² per gallon?
Yes. Select ft²/gal as the coverage unit and enter the product value. The calculator converts it internally so all results remain consistent.
7) Does the time estimate include prep and curing?
No. Labor-hours reflect application time from your productivity input. Add separate allowances for masking, surface repairs, drying intervals, and weather impacts.