Methodology: how we calculate materials

These are the general criteria we use to guide the calculations. The editable fields in each calculator let you adjust values when your supplier indicates a different coverage, density, or yield.

General principles

Each calculator normalizes the dimensions to the chosen measurement system before calculating area, volume, weight, or coverage. We always show the main formula and a practical example so you can check the result by hand. We work with two systems:

• Metric (Europe/LatAm): meters, centimeters, square meters, cubic meters, liters, and kilograms.
• American (US): feet, inches, square feet, cubic feet, cubic yards, gallons, and pounds.

Waste and rounding

Waste is applied as an extra percentage on top of the theoretical quantity. It covers real job-site losses: cuts, spills, uneven ground, compaction, and touch-ups. Units bought whole —bags, sacks, boxes, pieces, or cans— are rounded up to avoid incomplete purchases. Coverage, yield, density, compaction, cuts, and product brand can change the actual result; for critical projects, always verify with your supplier or a professional.

Unit conversions we use

• Metric: tonnes = kilograms ÷ 1000.
• American: cubic yards (yd³) = cubic feet (ft³) ÷ 27; short tons = pounds ÷ 2000.
• 1 cubic meter (m³) = 1000 liters (L).
• Depths and thicknesses in inches are converted to feet (÷ 12) before calculating volumes in cubic feet.

Criteria per calculator

Paint	Wall area minus doors and windows, multiplied by coats and waste, divided by the coverage per liter or gallon.
Concrete	Geometric volume of a slab, footing, or column, waste adjustment, and rounding of bags based on yield.
Gravel	Volume from length, width, and depth; estimated weight with editable density and conversion to tonnes or short tons.
Sand	Volume and weight from editable density, with results in m³ or yd³ and kg or lb depending on the measurement system.
Soil / Substrate	Volume of rectangular beds or round pots, waste adjustment, and bags based on the chosen size.
Mulch	Area times layer depth, conversion to liters or cubic feet, and bags rounded up.
Tile	Area to cover divided by the area of each piece, with waste for cuts, and boxes based on pieces per box.
Flooring	Room area with waste divided by the product's coverage per box.

Reference values

When you don't provide your own value, we use common industry references that you can override: gravel density ≈ 1600 kg/m³ (100 lb/ft³), sand density ≈ 1500 kg/m³ (95 lb/ft³), paint coverage ≈ 10 m²/L (350 ft²/gal), and concrete yield ≈ 0.0225 m³ per 50 kg bag (0.60 ft³ per 80 lb bag). These values vary by product: always adjust according to the label or technical sheet.

The estimates are for guidance only. The actual amount may differ due to project conditions and product specifications. For structural elements, consult an engineer or professional.