Calculator inputs
Use for garden paint, sealers, stains, and protective coatings.
Formula used
The estimator adjusts label coverage for brush transfer, surface texture, and waste.
- Effective Coverage = Label Coverage × Efficiency × Texture × (1 − Waste%)
- Product Needed = (Area × Coats) ÷ Effective Coverage + Cleanup Extra
- Containers Needed = ceiling(Product Needed ÷ Container Size)
- Active Time = (Area × Coats) ÷ Brushing Speed
Tip: For very porous surfaces, reduce the texture factor first.
How to use this calculator
- Select your measurement system and area shape.
- Enter dimensions or provide a custom area value.
- Use the product label coverage for a smooth surface.
- Set coats, then adjust efficiency and texture realistically.
- Add a waste allowance for touch-ups and brush loading.
- Enter container size and price to estimate purchase totals.
- Press the button and download CSV or PDF if needed.
Example data table
| Project | Area | Coats | Label Coverage | Efficiency | Texture | Waste | Estimated Product |
|---|---|---|---|---|---|---|---|
| Raised bed seal | 18 m² | 2 | 10 m²/L | 0.85 | 0.85 | 8% | ~5.0 L |
| Fence stain | 45 m² | 1 | 12 m²/L | 0.80 | 0.80 | 10% | ~5.9 L |
| Garden gate paint | 9 m² | 3 | 9 m²/L | 0.90 | 0.95 | 6% | ~3.6 L |
| Potting bench finish | 6 m² | 2 | 11 m²/L | 0.88 | 0.90 | 7% | ~1.6 L |
Examples assume small cleanup extra and typical brush loss.
Article
Coverage planning for outdoor garden surfaces
Brush-applied coatings behave differently than spraying or rolling. On fences, planters, raised beds, and trellis panels, bristles hold material and deposit it unevenly. This estimator converts label coverage into an effective coverage rate so you can predict realistic purchase quantities and avoid mid-job shortages. It also helps compare products by normalizing assumptions.
Inputs that change real-world consumption
Coats multiply your total area, while surface texture reduces spread. Rough cedar, aged timber, porous masonry, and end-grain edges absorb more liquid, so the texture factor should be lowered. Brush efficiency captures transfer loss from drips, heavy loading, and bristle retention. Waste allowance covers tray loss, touch-ups, and small spills. If you back-brush after spraying, choose a higher efficiency but keep waste.
How the calculator converts label rates
The model starts with label coverage for a smooth surface, then applies three adjustments: efficiency, texture, and waste. Effective Coverage equals Label Coverage times Efficiency times Texture times one minus Waste percent. Product Needed equals Area times Coats divided by Effective Coverage, plus optional cleanup extra for edging and brush loading. Use custom area when measuring complex shapes or multiple small panels.
Choosing containers and budgeting accurately
Once total volume is calculated, the tool rounds up to whole containers based on your container size. Enter a price per container to estimate budget in your local currency. For large projects, consider buying one extra container to manage color matching, later repairs, and weather delays that extend working time. Record batch numbers so future touch-ups blend better.
Interpreting time estimates for scheduling
Active time is estimated from area, coats, and brushing speed. Use conservative speed values for intricate lattice, thin slats, or detailed trim. Time excludes drying and curing, which depend on humidity, temperature, and product chemistry. Schedule recoats using manufacturer guidance and protect surfaces from dew and irrigation. For shaded beds, allow longer open time and avoid late-evening application before temperature drops.
FAQs
What is brush efficiency and how do I choose it?
Brush efficiency estimates how much coating transfers to the surface versus staying in bristles or dripping. Use 0.80–0.90 for careful work, 0.65–0.75 for heavy loading or windy conditions, and closer to 0.95 for smooth, controlled brushing.
When should I reduce the texture factor?
Lower the texture factor for rough-sawn wood, weathered fences, porous masonry, bark, and end-grain edges. Start at 0.85 for lightly rough wood, 0.70 for very rough boards, and 0.55 for highly absorbent surfaces, then adjust after a small test patch.
Does the estimator include primer or multiple products?
It estimates one coating product at a time. If you apply primer plus topcoat, run the calculator separately for each product using its label coverage and your expected coats, then combine container counts and costs for purchasing.
How do I handle irregular shapes like trellises or lattice?
Measure major rectangles, then subtract openings, or estimate a net area percentage. For repeated panels, measure one panel and multiply by the count. If you already know the total area, select Custom area and enter it directly.
Why does the calculator add cleanup extra volume?
Brush work often needs extra coating for loading, cutting edges, and maintaining a wet edge. Cleanup extra also accounts for small leftovers that cannot be recovered. Set it to zero for tight budgeting, or keep a small value for better accuracy.
Is the time estimate the full project duration?
No. It estimates active brushing time only. Drying, curing, masking, prep sanding, and setup are excluded and can dominate the schedule. Use the estimate to plan labor blocks, then add manufacturer recoat windows and weather buffers.