{
    "name": "Paint Coverage Calculator",
    "url": "https://calculators.geekmidst.com/calculators/paint-coverage-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/paint-coverage-calculator.md",
    "category": "Construction",
    "description": "Estimate the paint for a room from its size, doors, windows, number of coats and the coverage on the tin, in litres, US gallons and cans.",
    "summary": "Paint needed is the area to paint times the number of coats, divided by the coverage printed on the tin (m² per litre or ft² per gallon).",
    "also_called": [
        "Paint estimator",
        "Wall paint calculator"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "units",
            "label": "Units",
            "type": "segmented",
            "default": "metric",
            "options": {
                "metric": "Metric",
                "imperial": "Imperial"
            }
        },
        {
            "name": "length",
            "label": "Room length",
            "type": "number",
            "default": "4"
        },
        {
            "name": "width",
            "label": "Room width",
            "type": "number",
            "default": "3.5"
        },
        {
            "name": "height",
            "label": "Wall height",
            "type": "number",
            "default": "2.5"
        },
        {
            "name": "doors",
            "label": "Doors",
            "type": "number",
            "default": "1",
            "optional": true
        },
        {
            "name": "door_area",
            "label": "Area of each door",
            "type": "number",
            "default": "1.9",
            "optional": true
        },
        {
            "name": "windows",
            "label": "Windows",
            "type": "number",
            "default": "2",
            "optional": true
        },
        {
            "name": "window_area",
            "label": "Area of each window",
            "type": "number",
            "default": "1.5",
            "optional": true
        },
        {
            "name": "ceiling",
            "label": "Paint the ceiling too",
            "type": "segmented",
            "default": "no",
            "options": {
                "no": "No",
                "yes": "Yes"
            }
        },
        {
            "name": "coats",
            "label": "Coats",
            "type": "number",
            "default": "2"
        },
        {
            "name": "coverage",
            "label": "Coverage per coat",
            "type": "number",
            "default": "10"
        },
        {
            "name": "can_size",
            "label": "Can size",
            "type": "number",
            "default": "4"
        }
    ],
    "outputs": [
        {
            "key": "litres",
            "label": "Paint needed",
            "format": "number"
        },
        {
            "key": "us_gal",
            "label": "Paint needed",
            "format": "number"
        },
        {
            "key": "cans",
            "label": "Cans to buy",
            "format": "integer"
        },
        {
            "key": "area_m2",
            "label": "Area to paint",
            "format": "number"
        },
        {
            "key": "area_ft2",
            "label": "Area to paint",
            "format": "number"
        }
    ],
    "formula": {
        "text": "Area = 2(L + W) × H − Doors − Windows (+ L × W for the ceiling);  Paint = Area × Coats ÷ Coverage",
        "variables": {
            "L, W, H": "room length, width and wall height",
            "Coverage": "area one litre or gallon covers in one coat"
        }
    },
    "worked_example": {
        "inputs": {
            "units": "metric",
            "length": "4",
            "width": "3.5",
            "height": "2.5",
            "doors": "1",
            "door_area": "1.9",
            "windows": "2",
            "window_area": "1.5",
            "ceiling": "no",
            "coats": "2",
            "coverage": "10",
            "can_size": "4"
        },
        "steps": [
            "Walls = 2 × (4 + 3.5) × 2.5 = 37.5 m²; less 1.9 m² door and 2 × 1.5 m² windows = 32.6 m².",
            "Paint = 32.6 × 2 coats ÷ 10 m²/L = 6.52 L.",
            "6.52 ÷ 4 L = 1.63 → 2 cans."
        ],
        "result": "Two coats on a 4 × 3.5 m room with 2.5 m walls take about 6.5 litres, so two 4-litre cans."
    },
    "interpretation": "Primer, a big colour change or fresh plaster usually needs an extra coat. Check the coverage on your actual product; it ranges widely.",
    "assumptions": [
        "Coverage is the same for every coat.",
        "Trim, skirting and doors themselves are not painted."
    ],
    "limitations": [
        "Textured or porous surfaces can halve the real coverage."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "How much does a litre of paint cover?",
            "answer": "Many emulsions state 10–14 m² per litre per coat on smooth walls; a US gallon typically covers 350–400 ft²."
        },
        {
            "question": "Should I subtract doors and windows?",
            "answer": "Yes for large openings. For a small room, leaving them in gives a useful margin."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Wall Plastering Quantity Calculator",
            "url": "https://calculators.geekmidst.com/calculators/wall-plastering-quantity-calculator"
        },
        {
            "name": "Drywall Sheet Count Calculator",
            "url": "https://calculators.geekmidst.com/calculators/drywall-sheet-count-calculator"
        },
        {
            "name": "Waterproofing Area Calculator",
            "url": "https://calculators.geekmidst.com/calculators/waterproofing-area-calculator"
        }
    ],
    "disclaimer": "Quantities are estimates. Confirm requirements with your engineer or supplier before ordering materials.",
    "publisher": "GM¹X CalcVerse"
}