Square Feet vs Square Metres
The handful of conversions that actually come up when buying materials.
Area
1 m² = 10.764 ft². 1 ft² = 0.0929 m². To go from square feet to square metres, divide by 10.764.
Volume and liquid
1 m³ = 1.308 yd³ = 35.31 ft³. 1 US gallon = 3.785 L. Paint coverage quoted as 350 ft²/gal is roughly 8.6 m²/L.
Do not convert by hand
Every calculator here has a metric/imperial switch that converts inputs and results together, so you never mix systems mid-calculation.