SumsibleMEASURE · ESTIMATE · PLAN
QUANTITY WORKSHEET / 04

Paint calculator

Estimate paint for walls and ceilings with opening deductions, coats and label coverage. Compare container sizes and keep finishes separate.

How to use this calculator
  1. Add each wall and ceiling separately. A rectangular room has two pairs of walls; duplicate equal walls or use identical copies. Floor area is not wall area.
  2. Use the opening helper for unpainted rectangles. Deductions apply to every copy of that wall.
  3. Check coats, label coverage per coat and container size; save each color, finish or primer as its own product.
Material quantity calculator

Your measurements

Units

Example values are loaded. Replace them with your measurements and product details.

Measurement method
Deduct a door, window or rectangle

Adds width × height × count to this area’s exclusions, per identical copy. Do not deduct it twice.

MATERIAL & ALLOWANCES

Use the coverage on your paint label. Surface texture and application affect the result.

Calculate paint from actual coated area

Measure each wall or ceiling as an area, subtract only the openings that will not be painted, and enter the number of coats. Coverage means area per unit of paint for one coat. The worksheet divides the total coated area by that coverage.

Keep surfaces separate when they use different paint, color, finish, primer or coverage. Two estimates can share a product only when their exact identifiers and coverage agree. Different colors are never intentionally pooled into one container count.

Painted area = sum((width × height − openings) × copies) Paint volume = painted area × coats / coverage per coat Adjusted paint = paint volume × (1 + allowance / 100) Containers = round up(adjusted paint / container volume)

Understand the inputs

Wall width / height
For a ceiling, these are its two planar dimensions. Copies apply to identical surfaces, including the same openings.
Coverage
Area covered by one US gallon or one liter in one coat. Use the actual product label and an assumption appropriate to the surface. A US gallon is not an Imperial gallon.
Coats
A positive whole number. Primer and finish coats with different products need separate estimates.
Container volume
The actual volume of one purchase unit. This tool rounds to identical containers; it does not optimize a mix of quarts and gallons.

Example: two walls with the same finish

Two walls are each 12 ft wide and 8 ft high. Each has 16 ft² of unpainted openings, leaving 160 ft² in total. For two coats at an entered 350 ft² per US gallon, the base estimate is about 0.914 US gal. A chosen 10% allowance increases it to about 1.006 US gal, so identical 1-US-gal containers round to two. A small change in allowance can legitimately cross a package boundary.

Common estimating mistakes

  • Using floor area instead of wall area.
  • Entering coverage for two coats and multiplying by two coats again.
  • Deducting a doorway from every wall copy when only one has that doorway.
  • Pooling different colors or finishes because the container volumes match.

What this estimate leaves out

The result does not determine surface preparation, primer requirements, drying time or suitability. Actual coverage varies. Trim and doors are not modeled automatically; add their measured paintable area under the correct product. No live prices or purchasing links are used.

Product information & references

Check the technical data sheet or label for your paint. A manufacturer calculator provides a useful second estimate, not a universal coverage factor.