Prescribing and safety: calculations

Question 1

Unit conversions

Answer 1

1g= 1000mg

1mg= 1000micrograms

1microgram= 1000nanograms

1L= 1000ml

Question 2

% and mg

Answer 2

2%= 2g in 100ml

• 2000mg in 100ml
• 20mg/ml

Question 3

ratios

Answer 3

1:1000 means 1g in 1000g or ml

• 1000mg in 1000ml
• 1mg/ml

Question 4

Note when calculating

Answer 4

2 step calculations

Dose unit conversions

Dose versus volume

Single versus 24 hour dose