Wall Paint Coverage Calculator
Calculate how many gallons of paint you need for walls. Enter wall area, subtract windows and doors, set coverage rate and coats for accurate estimates.
Door Paint Coverage Calculator
Calculate paint needed for interior and exterior doors. Enter door dimensions, number of doors, and coats to estimate gallons for both sides and edges.
in
in
in
sq ft/gal
Area per Door⧉
42.2 sq ft
Both sides + edges
Total Area⧉
422 sq ft
Gallons Needed⧉
2.11
Buy 3 gallons
Planning notes, formulas, and examples
About the Door Paint Coverage Calculator
Painting doors gives your home or building a fresh, updated look and protects the wood surface from wear and moisture. Each door has two faces plus edges, and the total paint area adds up quickly when you have multiple doors in a home. A standard interior door (3 ft × 6 ft 8 in) has about 40 sq ft of paintable surface when you account for both sides and edges.
This door paint coverage calculator estimates the total gallons of paint needed based on your door dimensions, the number of doors, and your desired number of coats. It factors in both faces of each door plus the top, bottom, and side edges for a complete coverage estimate.
Whether you're painting a single front door or all 15 interior doors in a home, This calculator helps you purchase the exact right amount of door paint.
When This Page Helps
Doors have more paintable surface than most people realize. With two sides and four edges per door, a single standard door has roughly 42 sq ft of surface. Multiply that by 8–15 doors in a typical home and you're looking at several gallons. This calculator prevents costly under- or over-buying.
How to Use the Inputs
- Enter the door height in inches (standard is 80 inches).
- Enter the door width in inches (standard is 36 inches for exterior, 30–32 for interior).
- Enter the door thickness in inches (standard is 1-3/8" interior, 1-3/4" exterior).
- Enter the number of doors to paint.
- Set the paint coverage rate (typically 350–400 sq ft/gal).
- Select the number of coats (2 is standard).
- Review the total gallons required.
Formula used
Face Area = (Height × Width ÷ 144) × 2 faces
Edge Area = (2 × Height + 2 × Width) × Thickness ÷ 144
Door Area = Face Area + Edge Area
Gallons = (Door Area × Doors ÷ Coverage) × CoatsExample Calculation
Result: 2.12 gallons
Each door face is 80 × 36 ÷ 144 = 20 sq ft, so both faces = 40 sq ft. Edges add about 2.2 sq ft per door. Total per door = 42.2 sq ft. For 10 doors: 422 sq ft. At 400 sq ft/gal and 2 coats: 422 ÷ 400 × 2 = 2.11 gallons. Buy 3 gallons.
Tips & Best Practices
- Remove doors from hinges and paint on sawhorses for a smoother finish.
- Paint edges first, then one face at a time to avoid drips and lap marks.
- Semi-gloss or satin finish is ideal for doors due to durability and easy cleaning.
- Sand between coats with 220-grit for a factory-smooth finish.
- For panel doors, paint the panels first, then the rails, and finally the stiles.
- Use a small foam roller for flat areas and a brush for panel details and edges.
How to Estimate Paint for Doors
Each door has two primary faces and four edges. The face area is calculated from the door height and width. Edge area depends on the door thickness. Standard interior doors are 1-3/8" thick while exterior doors are 1-3/4" thick.
Door Sizes and Paint Requirements
Interior doors are typically 30", 32", or 36" wide by 80" tall. Exterior doors are usually 36" wide by 80" tall, though 42" and double-door entries exist. Closet doors may be bifold (24" per panel) or sliding, each with different surface area calculations.
Painting Technique for Doors
For the smoothest finish, remove the door and lay it flat on sawhorses. This eliminates drips and allows you to paint both sides and all edges systematically. Start with the edges, then paint one face completely, let it dry, flip, and paint the other face.
Panel Doors vs. Flat Doors
Flat (flush) doors are easiest to paint — simply roll one smooth surface. Panel doors require more technique: paint recessed panels first, then horizontal rails, and finally vertical stiles. This order ensures a consistent sheen and minimizes visible brush marks.
Sources & Methodology
Last updated:
Frequently Asked Questions
A standard interior door (30" × 80") needs about 35–40 sq ft of paint for both sides and edges. With 2 coats at 400 sq ft/gal, one door requires roughly 0.18–0.20 gallons, or less than a quart.
Yes. Always paint both sides for a professional appearance and to seal the wood against moisture absorption, which can cause warping over time. Even if one side faces a closet, painting both sides is recommended.
Yes. The hinge edge and latch edge should be painted. The top and bottom edges should be sealed at minimum to prevent moisture absorption. The latch edge typically matches the color of the side that opens toward the viewer.
Semi-gloss is the most popular choice for doors because it's durable, easy to clean, and highlights the door's profile. Satin finish is a good alternative for a slightly less reflective look.
A combination works best. Use a high-quality 2–2.5 inch brush for edges, panels, and detail areas. Use a 4–6 inch foam roller for large flat areas to achieve a smooth, stipple-free finish.
Plan about 30–45 minutes per coat per side for a standard door, including cutting in edges and rolling flat areas. With 2 coats on both sides plus drying time, a single door takes about a full day.
Prime bare wood, previously stained, or previously varnished doors. If the existing paint is clean and in good condition, a scuff-sand and direct topcoat is usually sufficient. Use a bonding primer over glossy surfaces.
Yes. Hollow-core doors paint well with standard latex paint. Avoid over-loading with paint which can cause the thin face veneer to warp. Apply thin, even coats and allow proper drying time between them.
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