Paint Calculator

Calculate how much paint you need for your walls and ceiling based on room dimensions, doors, windows, coverage, coats and wastage.

Room & Surface Inputs

1. Room Dimensions

straighten Room Length

square_foot Room Width

height Wall Height

Floor-to-ceiling clear height.

2. Doors & Windows Deductions

door_front Doors (Count & Avg Area)

sq.ft

Standard 7 × 3 ft door = 21 sq. ft.

window Windows (Count & Avg Area)

sq.ft

Standard 4 × 3 ft window = 12 sq. ft.

3. Painting Requirements & Coverage

roofing Include Ceiling Painting?

layers Number of Coats

coats

1 coat

4 coats

format_paint Manufacturer Paint Coverage

sq.ft/L

Coverage per litre per coat as stated on the paint container.

shield Wastage & Touch-up Allowance

25%

4. Paint Price & Optional Labour

payments Paint Price per Litre

₹

engineering Painting Labour Charges

₹

Total Paint Required

RECOMMENDED: 21 L

20.28 Litres

Total Surface Coverage: 1,844 sq.ft (across 2 coats). Estimated Paint Cost: ₹ 8,112 (Priced at ₹ 400 / L).

NOTE:

Opening deductions exceed total wall area. Please check door and window dimensions.

Paint Required

20.28 L

Coverage: 100 sq.ft/L

Paintable Area

922 sq.ft

2 Coats Applied

Estimated Paint Cost

₹ 8,112

Rate: ₹ 400 / L

Gross Wall Area

700 sq.ft

20 × 15 × 10 ft

Openings Deduction

-78 sq.ft

2 Doors + 3 Windows

Ceiling Area

300 sq.ft

Included: Yes

Waterfall & Litre Calculation

1. Gross Wall Area (2 × (20+15) × 10 ft) 700 sq.ft

2. Doors Deduction (2 × 21 sq.ft) -42 sq.ft

3. Windows Deduction (3 × 12 sq.ft) -36 sq.ft

4. Net Paintable Wall Area 622 sq.ft

5. Ceiling Area (20 × 15 ft) +300 sq.ft

                        6. Total Surface Area (922 sq.ft × 2 coats)
                        1,844 sq.ft
                    

7. Litres Required Before Wastage 18.44 Litres

8. Wastage Allowance Buffer (10%) +1.84 Litres

                        Total Paint Required
                        20.28 Litres
                    

Paint Estimation Insights

ℹ️ Surface Coverage: Applying 2 coats across 922 sq.ft paintable surface requires 1,844 sq.ft total paint coverage.
ℹ️ Wastage Buffer: A 10.0% wastage allowance adds +1.84 litres to cover roller absorption, edge trimming & touch-ups.

tips_and_updates

Verify Substrate & Finish Coverage: Smooth interior walls with acrylic emulsion offer ~110 sq.ft/L coverage, while rough exterior walls or dark base colors may require 20% more paint. Always check the container coverage guide.

This calculator provides an estimate based on the dimensions, openings, number of coats, paint coverage and wastage assumptions entered. Actual paint consumption can vary based on surface condition, texture, application method, product type, colour, primer, number of coats and workmanship. Always verify coverage and application requirements from the paint manufacturer's product information.

How Much Paint Do I Need?

Estimating room paint requires calculating gross wall area, deducting door and window openings, adding ceiling area, multiplying by number of coats, and applying a manufacturer coverage rate with a wastage buffer.

Step 1

Gross Wall Area

Multiply perimeter by height (2 × (Length + Width) × Height) to calculate gross wall surface area.

Step 2

Deduct Openings

Subtract the combined surface area of doors and windows to arrive at net paintable wall space.

Step 3

Add Ceiling Area

If painting the ceiling, add room length × width to the net paintable wall area.

Step 4

Multiply by Coats

Multiply total paintable area by the number of coats (standard is 2 coats) to calculate required surface coverage.

Before Buying Paint Checklist

✓ Measure room length, width, and clear wall height accurately.
✓ Count all doors and windows and subtract their surface areas.
✓ Confirm if ceiling is to be painted in the same or different color.
✓ Check the manufacturer's coverage rate (typically 90–120 sq.ft/L per coat).
✓ Buy a 10% extra buffer tin from the same batch for future touch-ups.

Frequently Asked Questions

How much paint do I need for a 20x15 ft room?

For a 20x15 ft room with 10 ft ceiling (including ceiling & 2 coats at 100 sq ft/L coverage), you need approximately 20.28 litres of paint including a 10% wastage allowance.

Should I include doors and windows in paint calculations?

No, door and window areas should be deducted from total gross wall area to determine true paintable surface.

How many coats of paint are recommended for interior walls?

Two coats are standard for most interior walls to ensure uniform color depth, hide underlying patches, and improve durability.