Construction Calculators
Jump to a tool or explore below.
Paint Calculator
Estimate how much paint you need for interior and exterior projects. Calculate gallons, coverage, coats, and total cost instantly.
Room Paint Calculator
Calculate paint requirements for walls, ceilings, and multiple coats
How to Calculate Paint
Everything you need to know about estimating paint for your next project
Coverage Rates by Paint Type
- Standard Wall Paint:Covers approximately 350 sq ft per gallon on smooth, primed surfaces
- Ceiling Paint:Covers approximately 400 sq ft per gallon due to thicker, drip-resistant formula
- Primer:Covers approximately 300 sq ft per gallon and is essential for bare surfaces or color changes
- Textured Surfaces:Covers only 200 sq ft per gallon on stucco, brick, or heavily textured walls
Choosing the Right Paint
- Flat / Matte:Best for ceilings and low-traffic rooms; hides imperfections well
- Eggshell:Popular for living rooms and bedrooms; slight sheen with good washability
- Satin:Ideal for kitchens, bathrooms, and hallways; durable and moisture-resistant
- Semi-Gloss:Great for trim, doors, and cabinets; highly durable and easy to clean
- High-Gloss:Best for accents and high-traffic areas; most durable but shows imperfections
Surface Preparation
- 1Clean walls with a damp cloth or TSP solution to remove dust and grease
- 2Fill holes and cracks with spackle, then sand smooth once dry
- 3Apply painter's tape along trim, ceilings, and edges for clean lines
- 4Prime bare drywall, repaired areas, or when making drastic color changes
- 5Lightly sand glossy surfaces so the new paint adheres properly
Pro Tips for Painting
- Buy Extra:Purchase 10-15% more paint than calculated to account for touch-ups and waste
- Two Coats Minimum:Always plan for at least two coats for even coverage and true color
- Use Primer Separately:A dedicated primer coat is more effective than paint-and-primer-in-one products
- Paint in Order:Start with the ceiling, then walls, then trim and doors for the cleanest results
- Temperature Matters:Paint between 50-85F (10-30C) and avoid high humidity for best adhesion and drying
How to Calculate Paint for a Room: Step by Step
Walk through a real example to see exactly how to estimate paint for a typical room.
Example: 12 x 14 Room with 9-Foot Ceilings
Step 1: Calculate total wall area
Perimeter = 2 × (12 + 14) = 52 linear feet
Step 2: Subtract doors and windows
Assume 1 door (21 sq ft) and 2 windows (2 × 15 = 30 sq ft):
Step 3: Divide by coverage rate
Standard interior latex covers ~375 sq ft per gallon:
Step 4: Multiply by number of coats
Two coats are recommended for even coverage:
Step 5: Estimate cost
At $35 per gallon for mid-range interior paint:
Add $15-25 for tape, rollers, and brushes if you don't already have supplies.
Paint Calculator FAQ
How much paint do I need for a 12x12 room?
About 1.5 gallons for walls only (384 sq ft of wall area minus doors/windows, at 350-400 sq ft/gallon coverage). Two coats doubles this to ~3 gallons.
How many square feet does a gallon of paint cover?
Most interior latex paints cover 350-400 square feet per gallon on smooth surfaces. Textured or porous surfaces reduce coverage to 250-300 sq ft/gallon.
How much does it cost to paint a room?
DIY: $50-100 for a 12x12 room (2-3 gallons of mid-range paint). Professional: $300-800 depending on room size, prep work, and ceiling height.
Do I need primer before painting?
Yes for new drywall, dark-to-light color changes, stained surfaces, and bare wood. Not needed when repainting similar colors with paint-and-primer products.
How many coats of paint do I need?
Two coats for best coverage and durability. One coat may suffice for touch-ups with the same color. Dark colors over light may need 3 coats.
What is the difference between flat, eggshell, and satin paint?
Flat: no sheen, hides imperfections, hard to clean (ceilings, low-traffic). Eggshell: slight sheen, washable (living rooms, bedrooms). Satin: noticeable sheen, very washable (kitchens, bathrooms, trim).
Need Material Takeoff Tools?
BuildVision AI automatically calculates material quantities from your plans, including paint, finishes, and surface area requirements.
Related Tools & Resources
Email this calculation and keep the template
We’ll send the editable worksheet, plus pro tips to tighten your estimate.
Editable spreadsheet you can share
1:1 walkthrough with our team
Follow-up reminders so it gets done
Keep momentum on this construction calculator
We’ll send reminders, a clean export, and one pro tip to tighten your numbers.
Send this to my inbox
Share a work email and we’ll follow up with a clean copy plus next steps.