Paint Calculator

Paint Quantity & Finish — A Working Reference

Most Indian homes overspend on paint for two reasons: rooms are sized at the gross wall area (without subtracting doors and windows), and the wrong sheen is picked for the wrong room. The calculator above handles the arithmetic; this reference covers the surface-area method, coats and coverage, and the sheen-by-room rule — so you can sanity-check the BOQ before you place a hardware order.

Paintable Surface Area

A 12 m² wall almost never uses 12 m² of paint. Doors, windows, and the skirting band routinely subtract 30-40% from the gross wall area. The diagram below shows the arithmetic line by line for a typical 4 × 3 m wall.

Coats & Coverage

Each layer in a paint system has its own coverage rate. Skim putty covers ~10-12 m²/kg, primer covers ~10-12 m²/L, and finish emulsion covers ~110-150 sqft/L depending on tier. The total litres for a job = paintable area × number of finish coats ÷ coverage rate, with primer and putty added line by line. Skipping primer on new plaster doubles finish-paint absorption and produces a patchy, uneven look — false economy.

Sheen by Room

Sheen is the single biggest decision after colour. Matte hides imperfections but smudges; gloss is washable but reveals every roller mark. Each room has a sweet spot driven by traffic, moisture, and lighting.

Practical Notes

• Round up to real pack sizes. Paint comes in 1 L, 4 L, 10 L, and 20 L cans. The calculator rounds up — buying 17 L means buying a 20 L can; buying 9 L means a 10 L can, not 4 + 4 + 1.
• Buy 5-10% extra for touch-ups. Future spot repairs are difficult to colour-match across batches. Keep a sealed leftover litre per major colour for 12-18 months of touch-up work.
• Anti-fungal emulsion is non-negotiable in bathrooms. Steam + condensation = mould within 6-12 months on standard emulsion. Look for "anti-fungal" or "mould-resistant" on the can.
• Low-VOC for children's rooms. Volatile organic compounds offgas for weeks after application. Look for "low-VOC" or "zero-VOC" emulsion (e.g., Royale Health Shield, Berger BabySafe) for kids' rooms and bedrooms — a small premium for substantially cleaner air.
• Exterior emulsion is not interior emulsion. Exterior formulations resist UV, monsoon, and algae but cost 25-40% more. Don't cross-use; the wear pattern is wrong both ways.
• Two-coat rule, but verify. Light over dark, or any colour change > 2 shades, may need 3 coats — or a tinted primer. The calculator's default is 2 coats; bump to 3 if changing radically.

Cross-References

• Colour Palette Generator — pick the colours; this tool sizes the paint
• Painting Quality Checklist — what to check before signing off the painter's work
• Lighting Planner — colour temperature and paint sheen interact
• BOQ Calculator — paint slots into the larger interior BOQ

Disclaimer: Coverage rates and prices vary by brand, batch, and surface condition. The calculator uses published MRP and typical coverage figures; always confirm against the can label before finalising the order. Labour rates fluctuate with city and season; the BOQ is a starting estimate, not a fixed quote.