Measure length (L), width (W), and height (H) in the same units
Rectangular prism: Volume = L × W × H
Cube: Volume = s³ (side length s)
Cylinder: Volume = π × r² × h (radius r, height h)
Sphere: Volume = (4/3) × π × r³ (radius r)
Cone: Volume = (1/3) × π × r² × h
Pyramid (base is any polygon): Volume = (1/3) × (base area) × height
Triangular prism: Volume = (1/2) × base × height × length
General approach (any solid with known cross-sections): Volume = area of cross-section × thickness (or integrate if varying)
Displacement method (irregular solids): Volume = volume of displaced liquid = final water level − initial water level