Flow indices

Carr’s Index (%) = ((tapped density − bulk density) ÷ tapped density) × 100

Hausner Ratio = tapped density ÷ bulk density

Worked example

50 g of powder occupies 100 mL before tapping and 80 mL after tapping. Bulk density = 50 ÷ 100 = 0.50 g/mL. Tapped density = 50 ÷ 80 = 0.625 g/mL. Carr’s Index = 20%. Hausner Ratio = 1.25 (fair flow).