Paint Calculator for Furniture: How Much Paint You Need

A paint calculator for furniture works out how much paint you need to cover a piece of furniture, based on the surface area you enter and the paint’s coverage rate. You input the dimensions of each part (or the total area) and the number of coats, and it returns the required paint volume in liters or gallons. This guide explains the formula, how to measure your furniture, and common mistakes to avoid.

Formula

The calculator uses the standard paint calculation formula:

Paint needed (L) = (Total surface area (m²) × Number of coats) / Coverage (m²/L)

Where:

• Total surface area – the sum of all exterior surfaces you plan to paint, in square meters (m²). For a rectangular box (like a dresser or table), it’s 2×(length×width) + 2×(length×height) + 2×(width×height), but you only paint the visible sides, so adjust for what you actually cover.
• Number of coats – usually 2 for good opacity, but may be 1 for touch-ups or 3 for drastic color changes.
• Coverage – the area a liter of paint covers at the recommended film thickness, typically 8–12 m²/L for most furniture paints. Check the can label.

If you measure in inches and feet, convert to meters first: 1 inch = 0.0254 m, 1 foot = 0.3048 m. Or use square feet and coverage in ft²/gal, then convert: 1 gallon = 3.785 L.

Worked Example

Using the default values: a piece 120 cm long, 50 cm wide, 75 cm high, with 2 coats and a coverage of 10 m²/L.

1. Calculate surface area (box, all sides):
   2×(120×50) + 2×(120×75) + 2×(50×75) = 12,000 + 18,000 + 7,500 = 37,500 cm²
2. Convert to m²: 37,500 / 10,000 = 3.75 m²
3. Multiply by coats: 3.75 × 2 = 7.5 m²
4. Divide by coverage: 7.5 / 10 = 0.75 L

The calculator gives 0.75 L (0.20 gallons). For a real project, you’d buy 1 liter, as paint comes in standard sizes.

How to Measure Your Furniture

Furniture isn’t a perfect box – drawers, legs, and moldings add or subtract area. Here’s a practical method:

• Measure each visible side separately: top, front, back, left, right. For a dresser, you might skip the back if it’s against a wall, but if you’re painting it anyway, include it.
• For drawers: measure the front face only, not the inside (unless you’re painting the interior).
• For legs or spindles: treat them as cylinders, area = Ï€ × diameter × height. For a table leg 5 cm in diameter and 70 cm tall, that’s π×5×70 ≈ 1,100 cm² = 0.11 m² per leg.
• Add 10–15% for waste, drips, and touch-ups. This is especially important for porous wood or rough surfaces.

Coverage Rates and Paint Types

Coverage varies by paint type and surface:

• Chalk paint – often 8–10 m²/L, but may need a topcoat.
• Latex/acrylic – 9–11 m²/L on smooth surfaces.
• Oil-based enamel – 10–12 m²/L, but slower drying.
• Spray paint – coverage is usually given per can (e.g., 1–2 m² per can for light coats).

The surface matters: raw wood absorbs more, so you might get only 6–8 m²/L on the first coat. Primed or previously painted surfaces give closer to the label value. If you’re unsure, do a test patch: paint a 1 m² area and measure how much paint you used.

Common Mistakes and Misconceptions

One big mistake is forgetting to subtract areas you won’t paint, like the underside of a table or the back of a cabinet. Another is using the total surface area of a box formula when the piece has open shelves or cutouts – you’re overestimating. Also, don’t confuse coverage per liter with coverage per gallon. If the label says 400 ft²/gal, that’s about 10 m²/L (since 1 gal = 3.785 L and 400 ft² ≈ 37.2 m², so 37.2/3.785 ≈ 9.8 m²/L).

Another misconception:

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in l | Length | cm | 120 | 0
in w | Width | cm | 50 | 0
in h | Height | cm | 75 | 0
in coats | Coats | - | 2 | 1
in coverage | Coverage | m²/L | 10 | 1
out area | Surface area | m² | (l*w*2 + l*h*2 + w*h*2) / 10000 | 2
out paint_l | Paint needed | L | (area * coats) / coverage | 2
out paint_gal | Paint needed | gal | ((area * coats) / coverage) * 0.264172 | 2