Free Paint Calculator

To calculate how much paint you need, measure the total surface area of your walls and ceiling in square feet. Divide that number by the paint's coverage rate — typically 300 to 400 sq ft per gallon — then multiply by the number of coats you plan to apply. Add a 10% waste factor for uneven surfaces, cut-ins, and touch-ups. For example, a 400 sq ft surface with 2 coats at 350 sq ft/gal coverage needs approximately 2.3 gallons. Use our free paint calculator above for an instant, accurate estimate.

The amount of paint you need depends on three factors: total surface area in square feet, the coverage rate of your chosen paint (latex covers about 300–400 sq ft/gal, oil-based about 350–450 sq ft/gal), and the number of coats. Most interior projects require 2 coats for full coverage. Enter your room dimensions into our free online paint calculator to get an instant breakdown of gallons needed, primer volume, and estimated cost.

For a standard room, calculate the wall area with the formula: 2 × (length + width) × ceiling height. A typical 12×14 ft room with 8 ft ceilings has approximately 352 sq ft of wall area. After deducting about 36 sq ft for a standard door and window, you need roughly 1.8 gallons of paint for 2 coats (at 350 sq ft/gal coverage). If you're also painting the ceiling, add length × width (168 sq ft for a 12×14 room), bringing the total to about 322 sq ft net area. Our room paint calculator handles all deductions automatically.

Ceiling paint coverage is straightforward: multiply length × width to get the total area. A standard 12×14 ft ceiling equals 168 sq ft, which requires approximately 0.48 gallons for 2 coats at 350 sq ft/gal coverage — essentially half a gallon. For a larger 15×20 ft ceiling (300 sq ft), you'd need about 0.86 gallons for 2 coats. Always round up to the nearest whole gallon and add 10% for waste. Textured ceilings may require up to 25% more paint due to surface absorption.

To estimate exterior paint, measure the total surface area of all exterior walls — multiply each wall's length by its height — then subtract windows and doors. Exterior surfaces are rougher and more porous than interior walls, so coverage is typically lower at 250–350 sq ft per gallon. Most exterior jobs require 2 coats of topcoat plus a primer coat. For a 2,000 sq ft exterior with 2 coats, expect to need approximately 5.7 to 8 gallons of paint. Factor in additional paint for trim, fascia, and detailed areas.

Divide your total paintable area (in square feet) by the paint's coverage rate, then multiply by the number of coats. As a quick reference: 1 gallon covers about 350 sq ft for one coat of standard latex paint. For a 1,400 sq ft area with 2 coats, you need 1,400 ÷ 350 × 2 = 8 gallons. Always add a 10% waste factor and round up to the nearest whole gallon. Our paint quantity calculator gives you the exact number, including waste optimization.

Always round up to the nearest whole gallon after calculating your exact needs. Add a 10% waste factor to account for uneven surfaces, roller absorption, brush cut-ins, and future touch-ups. Buy all the paint you need from the same batch or store visit to ensure color consistency — different production runs can have slight shade variations. For large projects, consider 5-gallon buckets for a 5–10% cost savings over individual gallons. Our paint cost calculator helps you optimize your purchase across gallon and 5-gallon bucket pricing.

To estimate a paint job, follow these steps:

1. Measure all surfaces to be painted — walls, ceilings, trim — in square feet.
2. Subtract non-painted areas like doors, windows, and fixtures.
3. Divide the net area by your paint's coverage rate and multiply by the number of coats.
4. Add 10% waste.
5. Calculate material cost by multiplying gallons by price per gallon.
6. Estimate labor based on area — professional painters typically cover 100–150 sq ft per hour.
7. Factor in prep work like sanding, priming, and masking tape.

Use our suite of calculators to automate each step.

The material cost to paint a standard 12×14 ft room is approximately $90–$180, depending on paint quality. Budget paints run $25–$35/gallon, mid-range $35–$55/gallon, and premium paints $60–$90+/gallon. A room this size needs about 1.8 gallons for 2 coats on the walls (or ~2.5 gallons including the ceiling). Professional labor adds $200–$600 for an average room depending on your region and prep requirements. Our paint cost calculator factors in gallon vs. 5-gallon bucket pricing to find the most affordable option for your project.

Painting an average-sized room (12×14 ft) takes approximately 6–10 hours total. Breakdown: prep work (taping, covering furniture, cleaning walls) takes 1–2 hours. The first coat takes 2–4 hours depending on method (brush, roller, or sprayer). Allow 2–4 hours of dry time between coats for latex paint (24 hours for oil-based). The second coat takes another 1–2 hours. Full paint curing takes 14–30 days depending on paint type and conditions. Temperature and humidity significantly affect drying — ideal conditions are 50–85°F with less than 85% relative humidity.