% w/v

percent weight per volume

Concentration

Percent weight per volume is grams of solute per 100 mL of solution, the form used for laboratory reagents and medical solutions: physiological saline is 0.9% w/v, meaning 9 g of sodium chloride per litre.

Watch out: Despite the % sign this is a mass per volume, not a ratio, and it equals % w/w only when the solution's density is 1.00 g/mL. For dilute aqueous reagents that is close enough; for anything concentrated or non-aqueous it is not. A 50% w/v sugar syrup is about 39% w/w.

1 % w/v 1 %