Summary NUR 206 Formulas For Medication Calculations

Conversion Table
• 1 kilogram (kg) = 1000 grams (g)
• 1 gram (g) = 1000 milligrams (mg)
– Convert Grams to Milligrams by Multiplying grams by 1,000
– Convert Milligrams to grams by dividing milligrams by 1,000
• 1 milligram (mg) = 1000 micrograms (mcg)
• Grains (gr.) 15 = 1 Gram (g) or 1000 milligrams (mg)
– To convert g. to gr multiply by 15
– To convert gr to g divide by 15.
• 1 Grain (gr.) = 60 Milligrams (mg)
– To convert gr. to mg multiply gr. by 60
– To convert mg to gr. divide mg. by 60
• 1ml = 1 cc
• 1 ounce = 30 ml
• 1 tablespoon (T or tbsp) = 15 ml
• 1 teaspoon (t or tsp) = 5 ml
• 2.2 lb = 1 kg
• To convert pounds to kg divide pounds by 2.2
• To convert kg to pounds multiply by 2.2

How Many or How Much
D = Desired Dose
Q = Quantity of Solution
H = Strength on Hand
X = Unknown quantity of Drug

• Sample: Physician orders 500 mg of ibuprofen (desired Dose) for a patient and you have
250 mg (Quantity on Hand) tablets (Quantity of solution) on hand.

Solution: D ÷ H x Q = X 500mg ÷ 250 mg x 1 tablet = 2 tablets
Answer: 2 tablets.

Flow Rate (how many ml/hr)

Volume (mL)
= Y (Flow Rate in mL/hr)
Time (hr)


Example: Infuse 250 mL over the next 120 minutes by infusion pump.
Volume (mL)
= Y (Flow Rate in mL/hr)
Time (hr)
Convert 120 minutes to hours.
 min → hr ( ÷ by 60 )
 120 min ÷ 60 = 2 hr
250 mL
= 125 mL/hr
2 hr