Room & Interior
Interactive Planning StudioPaint Calculator
Determining wall surface area, subtracting openings, and factoring in coat coverage prevents mid-project store runs and costly leftover paint tins.
Project Parameters
Enter your exact dimensions and specifications
Architectural methodology
About the Paint Calculator
Quality architectural paint is an investment. High-pigment emulsions cover roughly 350 to 400 square feet per gallon (10 to 12 square metres per litre) on primed surfaces.
Raw drywall, porous plaster, and dramatic color transitions absorb significantly more pigment. Calculating net wall area by subtracting standard doors (approx. 20 sq ft) and windows (approx. 15 sq ft) ensures professional-grade accuracy.
Underlying Formula
Net Wall Area ÷ Coverage Rate × Number of Coats
Wall Area = 2 × (Length + Width) × Height – Openings | Paint = (Area × Coats) ÷ Coverage
Step-by-step guidance
How to Use This Tool
Follow these four essential steps to take accurate architectural measurements and prepare your project quantities.
Step 1
Input the room perimeter dimensions and ceiling height.
Step 2
Count your standard internal doors and window openings to deduct non-painted area.
Step 3
Choose your number of coats—two coats are standard for uniform sheen and depth.
Step 4
Check your paint manufacturer’s recommended coverage on the tin for fine-tuning.
Expert clarity
Frequently Asked Questions
Common queries answered by our architectural editors and renovation consultants.
How many coats of paint are typically required?
Two coats are almost always required for rich opacity and durability. When painting over dark colors with light tones, consider one coat of dedicated primer plus two finish coats.
How much paint does a standard ceiling require?
Ceiling area equals room length × width. A typical 12×14 ft bedroom ceiling (168 sq ft) requires approximately half a gallon per coat.
What if my walls have heavy texture?
Heavily textured surfaces such as rough plaster or brick increase surface area by 15% to 25%. Add an extra 20% to your paint volume estimate.
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