Paint Calculator
Fast, accurate and free online farby calculator tool running directly in your browser.
-
1Enter data
Enter content, paste text or load a file from disk. -
2Click the button
The tool will immediately process your data in the browser. -
3Get the result
Copy the finished text or save the file to your device.
return "Result ready in 0.1s";
}
Paint calculator
Rate this tool:
Related tools
Other tools you may find usefulHow does the paint calculator work and why is it worth using?
The paint calculator is a reliable online tool that helps you precisely plan your purchases before starting your painting job. Painting an apartment or house is one of the most common procedures for refreshing the interior, but correctly assessing the need for paint can be quite a challenge. Buying too little paint may result in the wall not being finished, which may result in a visible difference in shades after it dries and a new batch is purchased. On the other hand, purchasing too much paint (especially more expensive latex or ceramic paints) means unnecessary freezing of cash and problems with storing construction chemicals.
Our calculator allows you to calculate the area of walls and ceilings to be painted in two ways: by directly entering the area in square meters (m²) or based on simple room dimensions (length, width and height). The tool also takes into account the number of layers applied, the paint efficiency given by the manufacturer, and automatically converts the result into the number of cans with standard capacities: 2.5 l, 5 l and 10 l.
How to calculate the painting area and paint consumption?
Calculation of paint demand is based on a simple mathematical scheme:
- Wall area:Calculated as the sum of the areas of all painted surfaces. In the case of a room with dimensions L (length) and W (width) and height H, the area of the side walls is calculated by the formula:
2 × (L + W) × H. - Ceiling area:Corresponds to the floor area, i.e.
L × W. - Subtract the holes:The sum of the area of windows and doors should be subtracted from the total area (e.g. a typical door is approx. 1.6 - 2.0 m², a double-leaf window is approx. 2.5 m²).
After calculating the net area, we multiply it by the planned number of layers (it is usually recommended to paint twice). The final consumption value is obtained from the formula:
Liters of paint = (Net painting area × Number of layers) / Efficiency (m²/L)
Paint efficiency and the number of layers - what is worth knowing?
The paint efficiency specified by manufacturers (e.g. 10 m²/l or 14 m²/l) applies to applying one layer on a smooth, well-primed substrate. In real conditions, this performance may be reduced. Absorbent substrates (e.g. fresh gypsum plasters without primer) can absorb much more material. For this reason, painting fresh walls without prior preparation involves much higher consumption. It is always recommended to use an appropriate primer that will even out the absorbency of the wall.
The standard margin of safety for loss (stock) is **5%**. It covers spills and paint remaining on rollers, trays and brushes.
Efficiency of various types of paints (Table)
| Type of paint | Average efficiency from 1 liter | Number of recommended layers | Application and properties |
|---|---|---|---|
| Acrylic paint | 10 – 12 m² | 2 layers | Cheap refreshment of ceilings and lightly occupied rooms. |
| Latex paint | 10 – 14 m² | 2 layers | Washable, perfect for living rooms and bedrooms. |
| Ceramic paint | 12 – 16 m² | 1 – 2 layers | Stain-resistant, scrub-resistant (kitchens, corridors). |
Frequently asked questions (FAQ)
How to calculate the wall area of a painting room?
Measure the length, width and height of the room. Multiply the sum of the length and width by the height and multiply the result by 2. For example, a room 4m by 5m with a height of 2.5m has a wall area of: 2 × (4 + 5) × 2.5 = 45 m². The total area of windows and doors should be subtracted from this value.
How many liters of paint are needed for a room of 20 m² (floor area)?
Assuming a 4m × 5m room with a height of 2.5m, the wall area is 45 m² and the ceiling is 20 m². The total is 65 m². We subtract the window and door (e.g. 5 m²), which gives 60 m² for painting. When painting twice and with an efficiency of 10 m²/l, the consumption is: (60 m² × 2 layers) / 10 = 12 liters of paint. You should buy, for example, one 10 l bucket and one 2.5 l bucket.
Why is the efficiency of paint on the construction site lower than on the packaging?
The manufacturer's data is obtained in laboratory conditions on perfectly smooth boards. In practice, consumption depends on the absorbency of the wall, the structure of the plaster (e.g. rough textured plaster increases consumption dramatically) and the type of tool used (a long-bristle roller applies a thicker layer of paint).
Is one coat of paint enough to cover a wall?
In most cases, it is necessary to apply two layers of paint to obtain full coverage, uniform color without streaks and stain resistance declared by the manufacturer. One layer usually occurs only when refreshing exactly the same wall color or when using very thick, single-layer premium paints.
How long does the paint dry before applying the second layer?
The drying time depends on the type of paint and the humidity in the room. At a temperature of approximately 20°C, latex and acrylic paints are dry to the touch after 1-2 hours. However, the next layer should be applied only after the coating has fully hardened, usually after 2 to 4 hours.