Maths for NursesDosage calculations

Skills Team

# 1W = What you want.

G = What you have got.

I = What it is in.

60 mg of pethidine is ordered.

Stock ampoules contain 100 mg in 2 mL.

So here W = 60 mg

G = 100 mg and I = 2 mL.

The units of Want and Got are the same – both are in mg.

Skills Team 2012

The formula is W x I G

60 X 2 = 120 = 1.2 mL 100 100

1.2 mL of stock should be drawn up.