Measure surfaces, pick coats, get liters fast. Compare units, add waste, and see total cost. Download tidy tables for planning, buying, and records later.
| Project | Net Area (m2) | Coats | Coverage (m2/L) | Waste % | Estimated Liters | Notes |
|---|---|---|---|---|---|---|
| Raised bed (rectangle) | 6.00 | 2 | 10.0 | 10 | 1.32 | Typical brush application. |
| Fence panel (wall) | 12.50 | 2 | 9.5 | 10 | 2.89 | Rough boards need higher waste. |
| Planter box (outside) | 7.80 | 3 | 10.0 | 12 | 2.62 | Extra coats around joints. |
| Garden table top | 2.40 | 2 | 11.0 | 8 | 0.47 | Smoother surfaces spread further. |
Net area comes from your selected geometry:
Material estimate follows these steps:
Coverage varies with texture, absorption, and application method. Always check the product label for the best baseline coverage.
This calculator supports four surface styles: custom total area, rectangle, wall/fence, and planter box. Rectangle uses length × width; wall uses length × height; planter sums side faces 2(L×H + W×H) and optionally the bottom. Planter projects can also include inside faces to double the coated shell when needed.
Product labels commonly state coverage as area per liter or per gallon. The calculator normalizes coverage to square meters per liter, so you can enter values like 10 m2/L or 350 ft2/gal and compare results consistently. Two coats suit many outdoor timber surfaces, while three coats are often used for end grain, joints, and splash zones. For accuracy, test a one meter patch, record spread rate, then buy enough for the whole job safely.
Deductions reduce net area for openings, gaps, or masked sections. A 5% deduction might represent hardware and voids on a trellis, while 15% can suit slatted panels. Waste captures absorption and tool loss; smooth sealed wood may work at 8%, but rough sawn boards often need 15–25% depending on porosity and roller nap.
After material liters are estimated, the calculator rounds up to whole containers based on your chosen package size. This protects you from shortages mid-coat and helps plan store trips. Adding a per-container price returns an estimated project cost, useful for comparing brands or deciding between 1-gallon and 5-liter packs when availability varies.
Recoat windows depend on temperature, humidity, and film thickness. Enter expected drying hours per coat and apply a weather buffer for dew, shade, or rain risk. For example, 4 hours per coat with a 25% buffer yields 10.0 hours for two coats. Always confirm cure times for soil-contact items before planting.
Use the product label number whenever possible. If you only have feet per gallon, select that unit and enter the same value. If you are unsure, start with 9–11 m2/L for smooth wood and increase waste for rough grain.
Deductions reduce the net area before coats are applied. Enter a percentage for sections you will not coat, such as openings, hardware zones, or masked edges. The calculator multiplies area by (1 − deduction%).
Use three coats for outdoor exposure, heavy splash areas, and end grain. It is also common for planter boxes, especially around joints. Two coats may be adequate on previously sealed, smooth surfaces when the label allows.
8–12% suits smooth, sealed surfaces. 15–25% is typical for rough lumber, porous end grain, or heavy roller texture. Increase waste if you expect drips, overspray, or frequent tray refills.
Most coatings are sold in fixed package sizes. Rounding up prevents running short between coats and accounts for unavoidable losses. Any calculated leftover can be saved for touch ups if stored according to the label.
No. The weather buffer only adjusts the drying time estimate. It adds extra hours to account for dew, humidity, shade, or rain delays. Material needs are controlled by area, coats, coverage, deductions, and waste.
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.