Updated
Trip Cost Calculator
Bus, train, plane, ship or car — full trip cost with passengers.
CostNest Calculator
Paint Calculator
Find out exactly how many litres and tins of paint you need for your rooms. Supports emulsion, primer, weathercoat, enamel, texture paint and distemper. Add multiple rooms, include or exclude the ceiling, and get a total cost estimate. This paint calculator gives instant results with no signup required.
Includes 10% wastage buffer. Door deduction: 1.8 m² each. Window deduction: 1.2 m² each.
Paint Calculator
Room dimensions · Coats · Litres needed · Tin count · Total cost
Standard interior walls & ceiling · Coverage: 14 m² per litre per coat
Include ceiling in calculation
Door deduction: 1.8 m² each. Window deduction: 1.2 m² each. Includes 10% wastage buffer. Update price/litre to match your local brand (Berger, Asian, Nippon, etc.).
How to Use
- 1Select paint type — emulsion, primer, weathercoat, enamel, texture or distemper.
- 2Set dimension unit (feet or metres) and number of coats.
- 3Select your currency and enter price per litre for cost estimate.
- 4Toggle ceiling on or off based on your project.
- 5Enter room dimensions (L × W × H) and door/window count.
- 6Add more rooms with the 'Add Room' button for multi-room projects.
- 7Review total litres, recommended tin sizes and total cost.
Example Calculation
- Paint type: Emulsion (Interior)
- Room: 12 ft × 10 ft × 10 ft
- 2 doors, 2 windows, ceiling included
- 2 coats, 10% wastage
Result: ~6.2 litres needed — buy 1 × 4L + 3 × 1L tin
Formula Used
Wall area = 2 × (L + W) × H minus door and window deductions. Ceiling area = L × W (if included). Total area = walls + ceiling. Litres = (Total area × coats) ÷ coverage rate × 1.1 (10% wastage). Tin combination is optimised to minimise leftover paint.
Professional Painting Tips
- 1Always apply a primer coat on new plaster — it seals the surface and improves paint adhesion
- 2Sand the walls lightly between coats for a smoother finish
- 3Apply paint in the morning or evening — avoid painting in direct sunlight or extreme heat
- 4Use a roller for large flat areas and a brush for edges and corners
- 5Two thin coats give a better finish than one thick coat
- 6Stir paint thoroughly before use and between coats
- 7For exterior walls, use weathercoat or elastomeric paint — emulsion fades and peels outdoors
- 8Keep a leftover tin sealed for future touch-ups — colour matching later is difficult
Frequently Asked Questions
How does the paint calculator work?
It calculates the total paintable area of your rooms (wall area minus doors and windows, plus ceiling if selected). It then divides by the paint's coverage rate (m² per litre) and multiplies by the number of coats. A 10% wastage buffer is added automatically. The result is the litres needed, which is rounded up to the nearest practical tin combination.
How many coats of paint do I need?
For new walls: 1 coat of primer + 2 coats of emulsion or weathercoat is standard. For repainting in a similar colour: 2 coats is usually enough. For a colour change (dark to light or vice versa): 3 coats may be needed. This calculator lets you set any number of coats.
What is the standard coverage of emulsion paint?
Good quality interior emulsion covers approximately 12–16 m² per litre per coat. This calculator uses 14 m²/L for interior emulsion, 11 m²/L for exterior weathercoat, 12 m²/L for primer, 15 m²/L for enamel, 5 m²/L for texture paint, and 10 m²/L for distemper. Actual coverage depends on surface porosity and application method.
How do I calculate paint for irregular rooms?
For L-shaped or irregular rooms, split them into simpler rectangular sections and add each room separately using the 'Add Room' button. The calculator sums all rooms and gives a combined total.
Should I include the ceiling in the calculation?
It depends on your project. If you are painting the ceiling in the same paint type as the walls, include it. If you are using a separate ceiling paint or not painting the ceiling, toggle it off. The calculator has a ceiling toggle for this.
How accurate is the litre estimate?
The estimate is accurate within 5–10% for standard smooth walls. Rough or textured surfaces absorb more paint — add an extra 10–15% for such surfaces. Very porous or old walls may need an extra coat. The 10% wastage buffer in this calculator already accounts for minor overages.
Which tin sizes are recommended?
The calculator automatically suggests the best combination of 1L, 4L, 10L and 20L tins to meet your total requirement with minimum waste. For large projects, buy 20L drums for cost savings. Keep 1–2 small tins for touch-up work after the job is done.
What is the price of emulsion paint per litre in Bangladesh?
Approximate 2024–25 market prices in Bangladesh: Berger WeatherCoat Exterior — BDT 320–400/L. Berger Easy Clean Emulsion — BDT 280–350/L. Asian Paints Tractor Emulsion — BDT 260–320/L. Nippon Paint — BDT 300–380/L. Update the price field with your actual supplier quote for an accurate cost.