Buying too much paint is wasted money. Buying too little is a half-day delay while someone runs to fetch more. Here's the formula we use to estimate paint for any Indian home — and the rules of thumb that save you from over- or under-ordering.
The formula
Paint needed (litres) = (Wall area sq.ft. × Number of coats) ÷ (Coverage × 0.9)
Where:
- Wall area sq.ft. = sum of all wall surfaces being painted
- Number of coats = usually 2 for normal repaint, 3 for dark colour over light
- Coverage = litres-per-sq.ft. from the paint can label
- 0.9 = a 10% wastage factor (brushes, drips, touch-ups)
Step 1: Calculate wall area
For each room, the wall area is roughly:
Wall area = Floor area × 3.5
This is a quick approximation for standard 10-ft ceiling Indian rooms. A 100 sqft room has about 350 sqft of paintable wall.
Exact method (if you want to be precise):
- For each room, measure perimeter (L1+L2+L3+L4 in feet)
- Multiply by ceiling height
- That's the room's wall area
- Subtract door/window area (1 door = ~21 sqft, 1 window = ~12 sqft typical)
- Add the room's ceiling area (= floor area) if painting ceilings too
Example: a 1200 sqft 2BHK
| Room | Floor area (sqft) | Wall area estimate (sqft) |
|---|---|---|
| Living + Dining | 350 | 1,000 |
| Master bedroom | 150 | 480 |
| Bedroom 2 | 120 | 380 |
| Kitchen | 100 | 320 |
| Bathroom 1 + 2 | 80 | 250 |
| Hallway / circulation | 100 | 320 |
| Total interior | ~2,750 sqft |
Subtract for doors (5 doors × 21 sqft = 105) and windows (8 windows × 12 sqft = 96).
Net interior wall area: ~2,549 sqft.
Step 2: Add ceilings and exteriors
Ceilings: same as floor area. For this 2BHK, that's ~1,200 sqft of ceiling.
Exteriors: usually similar to interior wall area for a single-storey home (because the external perimeter × height ≈ internal wall surface). For multi-storey, exterior is proportionally less than interior.
For this 2BHK G+0 example:
- Interior walls: 2,549 sqft
- Ceilings: 1,200 sqft
- Exterior walls: ~1,800 sqft (less than interior because no internal partitions counted)
Step 3: Apply the formula
Using paint coverage of ~110 sqft per litre (typical for Tractor Emulsion or Royale):
Interior emulsion (2 coats over primer):
Litres = (2,549 × 2) ÷ (110 × 0.9) = 51.5 L
Round up to 55 L (2 buckets of 20L + 1 bucket of 10L + a 1L tin for touch-ups).
Ceiling distemper / emulsion (2 coats):
Litres = (1,200 × 2) ÷ (110 × 0.9) = 24.2 L
Round up to 27 L.
Exterior emulsion (Apex, 2 coats):
Litres = (1,800 × 2) ÷ (100 × 0.9) = 40 L
Round up to 42 L (2 × 20L + 1 × 4L).
Primer (1 coat under each finish coat):
Interior + ceiling + exterior primer:
(2,549 + 1,200 + 1,800) ÷ (140 × 0.9) = 44 L
Round up to 48 L. (Primer covers more sqft/L because it's thinner.)
Wall putty (2 thin coats):
Coverage ~50 sqft per kg (for two coats).
Putty kg needed = 2,549 ÷ 50 = 51 kg
Round to 60 kg (3 bags of 20kg or one 40kg + one 20kg).
Step 4: The shopping list
For this 2BHK example:
| Item | Quantity | Approx. cost |
|---|---|---|
| Asian Paints TruCare Wall Putty 20 kg | 3 bags | ₹1,860 |
| Asian Paints Wall Primer (10L) | 5 cans | ₹11,000 |
| Tractor Emulsion (20L) | 2 buckets + 1 × 10L | ₹9,500 |
| Royale Luxury Emulsion (10L) — for showcase rooms | 1 bucket | ₹3,000 |
| Apex Weatherproof (20L) | 2 buckets + 1 × 4L | ₹14,500 |
| Rollers, brushes, putty knives | assorted | ₹1,500 |
| Total | ~₹41,360 |
Plus labour: ₹15–₹25/sqft of paint area = ₹38,000–₹64,000 for this 2BHK.
See Asian Paints, Birla Opus, and primer at Suppliable →
Shortcuts for common sizes
If you don't want to do the math, here are the totals for typical Indian home sizes (single-storey, standard 10ft ceilings):
| Built-up area | Interior emulsion | Exterior emulsion | Primer | Putty |
|---|---|---|---|---|
| 600 sqft (1BHK) | 30 L | 22 L | 25 L | 35 kg |
| 1,000 sqft (2BHK) | 50 L | 40 L | 45 L | 55 kg |
| 1,500 sqft (3BHK) | 75 L | 60 L | 68 L | 80 kg |
| 2,000 sqft (3BHK premium) | 100 L | 80 L | 90 L | 105 kg |
| 3,000 sqft (4BHK villa) | 150 L | 120 L | 140 L | 160 kg |
Add 10-15% for 3-coat jobs (dark colours over light, or very contrasting colour change).
Pro tips that save 10-20% on paint cost
Buy the biggest pack you can use. Per-litre cost drops 10-15% from 1L to 20L sizes.
Tint at home, not at the shop. Bring back leftover paint and tint to a different colour for accent walls. Asian Paints supplies free tinting at most dealers.
Plan colour zones. Group rooms by colour so you can mix one large batch instead of small batches. Reduces waste.
Buy primer + paint together from the same brand. Compatibility issues cause peeling.
Track open buckets. A bucket left open for 6 hours loses 5-10% to surface skinning. Lid tight, store cool.
Common mistakes
- Skipping the wastage factor. Painters waste 5-15% to drips, brush cleaning, and partial buckets. Always order 10% more than the math says.
- Not buying a touch-up tin. A 1L can of every colour you used, stored for 1-2 years, lets you fix scuffs cheaply.
- Counting only floor area. Wall area is ~3.5× floor area. People often under-order by half.
- Forgetting the ceiling. It's a big surface, easy to leave out of the estimate.
- Using too thin a primer coat. Save the primer cost and your finish coats won't adhere. False economy.
When to call us
If you're not sure of your wall area, just give us the built-up sqft of the home (or the floor plan if you have it) — WhatsApp us at +91 87786 27926 — and we'll give you the full paint BOM in a single message. Delivery to your Chennai site in 60 minutes.
Paint team at Suppliable. Browse painting products →