Can I paint over old paint?

Yes, if existing paint is in good condition (not peeling, flaking, or bubbling). Clean walls, patch holes, sand glossy areas, and use primer if needed. Cannot paint over: peeling paint, water damage, mold, wallpaper (remove first), glossy paint without sanding. When in doubt, test a small area first.

Calculators Home ImprovementPaint Calculator

Paint Calculator

Name: CraftCalc
Price range: Free

Calculate paint coverage, gallons needed, and costs for walls, ceilings, and rooms. Free professional tool for perfect paint estimates.

Paint Requirements

Room Length (feet)

Room Width (feet)

Ceiling Height (feet)

Number of Doors

Number of Windows

How to Calculate Paint Coverage

Measure Room Dimensions

Measure length and width of each wall in feet. For ceiling, measure length × width of the room floor. Record all measurements. Don't forget to include closets if painting them!

Calculate Wall Square Footage

For each wall: Length (ft) × Height (ft) = Square Footage. Add all walls together for total wall area. Example: 12ft wide × 8ft tall wall = 96 square feet.

Subtract Doors and Windows

Standard door: 20 sq ft each. Standard window: 15 sq ft each. Subtract these from total wall area. Don't over-subtract - paint the space anyway to avoid running short.

Determine Coats Needed

Light color over light color: 2 coats. Dark to light color change: 2-3 coats + primer. New drywall: 1 primer + 2 coats. Use high-quality paint to reduce coats needed.

Calculate Gallons Needed

Divide total square footage by 350 (coverage per gallon). Multiply by number of coats. Add 10-15% extra for touch-ups, waste, and mistakes. Always round up to the nearest gallon when buying.

Paint Types & Finishes Guide

Paint Base Types

🎨 Latex (Water-Based) Paint

Pros: Low odor, easy cleanup with water, dries fast (1-2 hours), low VOCs, flexible (won't crack)

Cons: Less durable than oil-based, not ideal for high-moisture areas

Best For: Interior walls, ceilings, most home painting projects

Cost: $20-60/gallon

🖌️ Oil-Based (Alkyd) Paint

Pros: Extremely durable, smooth finish, excellent adhesion, stain-resistant

Cons: Strong odor, requires mineral spirits for cleanup, slow drying (8-24 hours), yellows over time

Best For: Trim, doors, cabinets, high-moisture areas, outdoor furniture

Cost: $30-75/gallon

⚪ Primer

Purpose: Seals surfaces, blocks stains, improves paint adhesion, ensures even color

When Needed: New drywall, patched walls, dramatic color changes, glossy surfaces, stained areas

Types: Stain-blocking (best for water stains), bonding (for glossy surfaces), drywall primer

Cost: $15-35/gallon

Paint Finishes (Sheens)

Flat (Matte) Finish

Sheen: No shine, non-reflective

Best For: Ceilings, low-traffic areas, bedrooms

Pros: Hides surface imperfections, elegant look

Cons: Hard to clean, shows marks easily, not scrubbable

Use where minimal touching/cleaning needed

Eggshell Finish

Sheen: 10-25% gloss, subtle sheen

Best For: Living rooms, dining rooms, bedrooms, hallways

Pros: Washable, hides minor imperfections, elegant appearance

Cons: Shows application flaws more than flat

Satin Finish

Sheen: 25-35% gloss, soft sheen

Best For: Kitchens, bathrooms, hallways, kids' rooms

Pros: Very washable, moisture-resistant, durable

Cons: Shows surface imperfections, application marks visible

Best balance of durability and appearance

Semi-Gloss Finish

Sheen: 35-70% gloss, noticeable shine

Best For: Trim, doors, cabinets, bathrooms, high-moisture

Pros: Highly durable, very washable, moisture/stain resistant

Cons: Highlights all surface imperfections

Professional choice for trim and high-use areas

High-Gloss Finish

Sheen: 70-85% gloss, mirror-like shine

Best For: Furniture, front doors, cabinets, accent features

Pros: Extremely durable, ultra-washable, dramatic look

Cons: Requires perfect surface prep, shows every flaw

Use sparingly for maximum impact

2025 Paint Cost Guide

Paint Prices per Gallon

💵 Budget Paint

$15-25

Examples: Valspar 4000, Behr Dynasty

• Coverage: 250-300 sq ft/gal

• Coats needed: 3-4

• Lifespan: 3-5 years

Good for rentals, garages

⭐ Mid-Range Paint

$30-45

Examples: Behr Premium Plus, SW ProMar

• Coverage: 350-400 sq ft/gal

• Coats needed: 2-3

• Lifespan: 5-8 years

Best value for most projects

🏆 Premium Paint

$50-80

Examples: SW Emerald, BM Aura

• Coverage: 400-450 sq ft/gal

• Coats needed: 1-2

• Lifespan: 10-15 years

Lowest long-term cost

Total Project Costs (12×12 Room Example)

Cost Type	DIY	Professional
Paint (2 gallons)	$60-90	$60-90
Supplies (roller, tape, etc)	$30-50	Included
Labor	Your time (8-12 hrs)	$300-600
TOTAL	$90-140	$360-690

Note: Professional painting costs $2-6 per square foot including labor and materials. Complex projects (high ceilings, textured walls, multiple colors) cost more. DIY saves 60-80% but requires time and skill.

10 Pro Painting Tips for Perfect Results

🎯 1. Invest in Quality Tools

A $15 roller vs $5 roller makes a huge difference. Quality tools apply paint smoother, hold more paint, don't shed lint, and last for multiple projects. Buy once, use forever.

🧹 2. Prep is 80% of the Job

Clean walls, patch holes, sand rough spots, caulk gaps. Poor prep = poor results. Professionals spend 4 hours prepping for every 1 hour painting. Shortcuts show forever.

📏 3. Use Painter's Tape Correctly

Apply on clean, dry surfaces. Press edges firmly. Remove tape while paint is still slightly wet (not dry!). Pull at 45-degree angle slowly. This prevents peeling and ragged edges.

⏰ 4. Don't Rush Between Coats

Wait full recoat time (check can - usually 2-4 hours). Painting wet paint pulls off the first coat. Rushing causes streaks, peeling, and uneven coverage. Patience = perfection.

🔄 5. Use the W-Pattern Technique

Roll paint in W or M pattern, then fill in without lifting roller. This distributes paint evenly, prevents lap marks, and gives smooth professional finish. Never roll in straight lines.

🎨 6. Cut In Before Rolling

Paint edges, corners, and trim with brush first (cut in). Then roll main areas while cut-in is still wet. This blends edges seamlessly and eliminates visible lines between brush and roller.

💧 7. Keep a Wet Edge

Always paint into wet paint, never let edges dry before connecting. Dried edges create lap marks and visible lines. Work in sections, maintain pace, don't take breaks mid-wall.

🌡️ 8. Control Temperature & Humidity

Ideal: 50-85°F, 40-70% humidity. Too hot: paint dries too fast (lap marks). Too cold: won't dry properly. High humidity: extended drying, potential mildew. Check weather before starting.

💡 9. Use Proper Lighting

Work with bright overhead lights plus portable work lights. Paint in good daylight when possible. Side lighting reveals flaws - inspect walls from different angles before considering them done.

🧪 10. Sample Colors First

Buy sample sizes ($5-8) and paint 2×2 ft squares. View in different lighting - morning, afternoon, evening, artificial light. Colors change dramatically with lighting. Test before buying gallons.

7 Painting Mistakes That Ruin Results

❌ Skipping Primer

Trying to save $15 on primer costs $60+ in extra paint coats. Primer blocks stains, seals porous surfaces, ensures true color, improves adhesion. Always prime new drywall, patched areas, and dramatic color changes.

❌ Buying Cheap Paint

$20 paint requires 4 coats and fails in 3 years. $50 paint needs 2 coats and lasts 10+ years. Cheap paint has less pigment, poor coverage, and doesn't hide. Premium paint actually costs less long-term.

❌ Painting Dirty Walls

Paint doesn't stick to dirt, grease, or dust. Clean walls with TSP cleaner or soap and water. Let dry completely. Dirt causes peeling, bubbling, and flaking within months. Cleaning takes 30 minutes, prevents years of problems.

❌ Overloading the Roller

Too much paint = drips, runs, uneven texture, wasted paint. Proper load: roll in tray 3-4 times, should be covered but not dripping. Light pressure, multiple passes better than heavy single pass.

❌ Not Protecting Floors/Furniture

Paint splatter is permanent on hardwood, carpet, and furniture. Use drop cloths (canvas better than plastic - plastic is slippery). Remove or cover everything. Cleaning paint is 10× harder than preventing it.

❌ Starting in the Wrong Order

Wrong: walls first, then ceiling. Right: ceiling → walls → trim. Paint falls down, not up. Ceiling splatter on walls can be covered. Wall paint on ceiling shows forever. Always work top to bottom.

❌ Leaving Tape On Too Long

Remove painter's tape when paint is slightly tacky (30-60 min), not fully dry. Dry paint bonds to tape causing ragged edges and pulling. Left for days, tape leaves adhesive residue impossible to remove cleanly.

Room-by-Room Paint Guide

🛏️ Bedrooms

Best Finish: Eggshell or Flat

Why: Low traffic, minimal cleaning needed

Color Tips: Lighter colors make rooms feel larger. Avoid bright colors that disrupt sleep.

Average room: 2-3 gallons

🛋️ Living/Dining Rooms

Best Finish: Eggshell or Satin

Why: Moderate traffic, occasional cleaning

Color Tips: Go bold - these rooms showcase your style. Test samples on multiple walls.

Average room: 3-4 gallons

🍳 Kitchens

Best Finish: Satin or Semi-Gloss

Why: High traffic, frequent cleaning, grease/moisture

Color Tips: Whites and light neutrals keep it feeling clean. Avoid dark colors that show splatter.

Average kitchen: 2-3 gallons

🚿 Bathrooms

Best Finish: Satin or Semi-Gloss

Why: High moisture, mildew concerns, frequent cleaning

Color Tips: Use mildew-resistant paint. Light colors make small bathrooms feel bigger.

Average bathroom: 1-2 gallons

🚪 Hallways

Best Finish: Satin

Why: High traffic, frequent touching/scuff marks

Color Tips: Light colors make narrow halls feel wider. Consider washable paint for kid-height marks.

Per 10 ft hallway: 1-2 gallons

🏠 Trim, Doors, Cabinets

Best Finish: Semi-Gloss or High-Gloss

Why: Very high wear, frequent touching, needs washing

Color Tips: White trim is classic and brightens rooms. Matching trim to walls modern but shows less dimension.

Trim in typical room: 1 quart - 1 gallon

Frequently Asked Questions

How do I calculate how much paint I need?

Calculate square footage by measuring length × width of walls and ceilings. Subtract doors (20 sq ft each) and windows (15 sq ft each). Divide total square footage by paint coverage rate (usually 350-400 sq ft per gallon). Add 10% extra for touch-ups and waste.

How much area does one gallon of paint cover?

One gallon of paint typically covers 350-400 square feet per coat on smooth surfaces. Textured or rough surfaces may only cover 250-300 sq ft per gallon. Primer coverage is similar. Always check manufacturer specifications as coverage varies by brand and type.

How many coats of paint do I need?

Most projects need 2 coats of paint. Primer + 2 coats for new drywall, dramatic color changes, or covering dark colors. Light-to-light color changes may only need 2 coats. Dark-to-light changes often require 3 coats. High-quality paint may cover in one coat.

Do I need primer before painting?

Yes for: new drywall, patched areas, dramatic color changes, glossy surfaces, stained/water-damaged walls. No for: repainting same color, using paint-and-primer combo on good surfaces. Primer improves adhesion, blocks stains, reduces coats needed, and ensures even color.

What is the difference between flat, eggshell, satin, and semi-gloss paint?

Flat (matte): No shine, hides imperfections, hard to clean. Best for ceilings, low-traffic areas. Eggshell: Slight sheen, easier to clean. Best for living/dining rooms, bedrooms. Satin: Soft sheen, washable. Best for kitchens, bathrooms, hallways. Semi-gloss: Noticeable shine, very durable and washable. Best for trim, doors, cabinets, high-moisture areas.

How much does paint cost per gallon in 2025?

Budget paint: $15-25/gallon. Mid-range paint: $30-45/gallon. Premium paint: $50-80/gallon. Designer brands: $80-120/gallon. Primer: $15-35/gallon. High-quality paint covers better, lasts longer (10+ years vs 3-5 years), and often requires fewer coats, making it more economical long-term.

Should I hire a professional or DIY paint?

DIY if: simple rectangular rooms, low ceilings, painting same color, you have time and patience. Cost: $0.50-1.50/sq ft (materials only). Hire professional if: high/vaulted ceilings, extensive trim work, textured surfaces, multiple colors, tight timeline. Cost: $2-6/sq ft including labor. Pros have tools, experience, and insurance but cost 3-5× more than DIY.