Measure Walls & Openings
30 minutesMeasure room length, width, and ceiling height. Record door and window dimensions to subtract from total paintable area. Note wall texture and existing color for coverage planning.
Field context
This workflow is part of 6 niche fields
Free step-by-step painting room for homeowners. Plan painting room with calculators and checklists covering measure walls & openings, calculate paint needed.
Measure room length, width, and ceiling height. Record door and window dimensions to subtract from total paintable area. Note wall texture and existing color for coverage planning.
Use wall area and desired coat count to estimate gallons of primer and finish paint. Add 10% waste allowance for cutting in and touch-ups.
Select paint colors and finish sheen based on room use. Buy sample quarts and test on the wall before committing to full gallons.
Clean walls with mild detergent, fill holes with spackle, sand smooth, and apply painter's tape along trim, ceilings, and outlets. Lay drop cloths and ensure ventilation.
Roll primer on large areas and cut in along edges with a brush. Allow full dry time before sanding lightly and inspecting for missed spots.
Cut in edges first, then roll walls in a W-pattern working in 3×3 ft sections. Maintain a wet edge to avoid lap marks. Apply second coat after full dry time.
Inspect walls under natural and artificial light. Touch up missed spots, remove tape while paint is slightly tacky, and reinstall hardware.
Estimate gallons of primer and finish paint based on room dimensions, openings, and coat count.
Calculate total wall and ceiling square footage before subtracting doors and windows.
Add waste allowance (typically 10%) and compare coverage rates across paint brands.
Compare prices and calculate savings when buying paint in bulk or during sales promotions.
Compare cost per square foot across different paint brands and container sizes.
Approximate coverage per gallon for one coat on smooth, properly primed surfaces.
| Surface Type | Coverage (sq ft/gal) | Notes |
|---|---|---|
| Smooth drywall | 350–400 | Standard latex interior paint |
| Textured drywall | 280–320 | Reduce coverage 10–20% |
| Previously painted | 375–425 | Primer may not be needed if color similar |
| Bare wood | 250–300 | Always prime first |
| Brick / masonry | 200–250 | Use masonry primer and paint |
| Ceiling (flat) | 350–400 | Use ceiling-specific flat paint |
Use a 2–2.5 inch angled brush to cut in along ceilings and trim before rolling. Keep a steady hand and reload brush frequently for clean lines without tape.
Roll in a W or M pattern, then fill in without lifting the roller. Finish each section with a single downward stroke to uniform the texture.
Subtract approximately 21 sq ft per door and 15 sq ft per window from total wall area. For rooms with many openings, recalculate rather than using a flat percentage.
Paint large swatches (2×2 ft) on different walls and observe at morning, midday, and evening light before buying full gallons.
Most latex paints require 50–85°F (10–29°C) and humidity below 85%. Avoid painting in direct sunlight on exterior walls — the paint may dry too fast and blister.