🎨 Paint Calculator

The Paint Math (Worked for 900 sqft Net Area)

Here is the exact computation the calculator runs, using 1000 sqft wall area minus 100 sqft deductions, interior emulsion (140 sqft/L), 2 coats:

1. Net paintable area: 1,000 − 100 = 900 sqft
2. Coverage: Interior emulsion = 140 sqft per litre per coat
3. Coats: 2 (standard for new paint jobs)
4. Base litres: 900 × 2 ÷ 140 = 12.86 litres
5. Add 10% wastage: 12.86 × 1.1 = 14.14 → 15 litres
6. 20-litre buckets: ceil(15 ÷ 20) = 1 bucket
7. Estimated cost: 15 × ₹250 = ₹3,750

Coverage rates are typical for quality emulsion paints (Asian Paints, Berger, Nerolac) on smooth plastered walls. Rough or unpainted surfaces absorb 20-30% more paint. Wastage factor of 10% accounts for roller absorption, spillage, and touch-ups.

Paint Quantity by Room Size

How much interior emulsion (2 coats) you need for common room sizes. Wall area = room perimeter × wall height, minus doors and windows.

The 1000 sqft house row is highlighted because wall area is typically 2.5-3× the floor area (all rooms combined). A 1000 sqft house has roughly 3,000 sqft of wall area including all rooms, corridors, and ceilings if painted.

Paint Type Coverage Comparison

Different paint types cover different areas per litre — this changes your total paint requirement:

Exterior paint covers less per litre because it's applied thicker for weather protection. Texture and designer finishes cover even less because of the heavy application method. Always prime before painting — primer seals the surface and reduces the topcoat absorption by 15-20%.

Common Advice vs Reality: "One Coat Is Enough for a Refresh"

Painters sometimes quote for 1 coat to keep the estimate low. In practice, 1 coat over an existing wall leaves visible patches and colour inconsistency, especially if the old colour differs from the new. For a refresh of the same colour in good condition, 1 coat may work. For any colour change or new plaster, 2 coats minimum. For light paint over dark walls, 3 coats or a primer base coat is needed — don't let a painter skip this to save cost.

The Common Mistake: Forgetting the Primer

People calculate only the topcoat and skip primer. Primer is cheaper (₹150-200/L vs ₹250/L for emulsion) and covers more (160 sqft/L vs 140), but it's essential — it seals fresh plaster, prevents moisture bleeding, and reduces the topcoat needed by 15-20%. Skipping primer to save ₹1,000 on a 1000 sqft job means your topcoat absorbs more, costing you ₹2,000-3,000 extra in topcoat paint. Always budget for primer first, then topcoat.

Edge Case: Fresh Plaster Absorbs 30% More Paint

Newly plastered walls are highly porous and absorb significantly more paint than previously painted walls. For fresh plaster, apply 1 coat of primer, wait 24 hours, then apply 2-3 coats of emulsion. Budget 30% more paint than the calculator shows for fresh plaster. The calculator's 10% wastage factor covers roller absorption and touch-ups but not the extra absorption of bare plaster.

Decision Framework: Which Paint Type?

• Interior walls (living room, bedroom): Interior emulsion (₹200-350/L). Washable, low-odour, fast-drying. Asian Paints Apex, Berger Easy Clean, Nerolac Beauty are popular.
• Exterior walls: Exterior emulsion (₹250-400/L). Weather-resistant, UV-stable, crack-bridging. Asian Paints Apex Ultima, Berger Weathercoat.
• Kitchen and bathroom: Waterproof emulsion or oil-based paint. Handles humidity and grease better than standard emulsion.
• Budget option: Distemper (₹80-150/L) for interior walls. Cheaper but less durable and not washable. Suitable for rental properties or temporary finishes.
• Premium option: Texture or designer finishes (₹400-800/L) for feature walls. High visual impact but higher cost and lower coverage.

The 2-Minute Self-Check

1. Measure each wall: length × height in feet. Sum all walls.
2. Subtract doors (~21 sqft each) and windows (~15 sqft each).
3. Enter the net area in the calculator with your paint type.
4. Add primer separately: run the calculator with "Primer" selected, 1 coat.
5. Buy 10% extra for touch-ups — unopened paint tins can be returned to most dealers.

Your Next Steps

1. Run the paint calculator for each room or your full house wall area.
2. Don't forget primer — calculate it separately with 1 coat.
3. Calculate other materials: Bricks, Cement, Steel.
4. See total project cost at the House Cost Calculator.
5. Check current paint and material prices in your city at our material prices page.

Editor Note

Reviewed June 2026. Coverage rates (140 sqft/L interior, 100 sqft/L exterior, 160 sqft/L primer) are typical for quality emulsion paints on smooth plaster. Fresh plaster absorbs 30% more paint. Wastage factor of 10% covers roller absorption and touch-ups. If you spot an outdated figure, please contact us.