Dose Calculation Formulas Nursing

The following are a few simple formulas that will help you calculate the dose of medication in adults, children and infants.

Dose Calculation Formulas Nursing

1 Weight/Pounds to Kg’s

  • To convert weight (in pounds) to kilograms:

70 lb = 70 x 2.2 = 142.5 kg

  • To convert weight (in kilograms) to pounds:
  • 5 kg = 142.5 x 0.454 = 69 lb
  • To convert from pounds/kilogram:

70 lb/kg = 0.351 kg/lb

2 Kilograms to Pounds

In order to convert from kilograms to pounds, you will need the following formula:

Conversion Formula:

1 lb = 453.59237 g

Explanation of Formula:

There are 16 ounces in a pound and 2,000 pounds in a ton. This means there are 16 x 453.6 g/pound = 6,350 grams per kilogram and 1 kg ~= 2.20462262 lbs (rounded). Therefore, 1 lb ~= 0.4535924 lb or 0.4535924 kg.

Examples of How to Convert from Kilograms to Pounds:

8 kg ~= 2282 lbs 5 oz or 1822 lbs 13 oz

3 Dose per kilogram

Dose per kilogram is the amount of medication given per kilogram of body weight. It is not the same as dose per kg/hour, which indicates how much medicine a patient receives over time. Dose per kg can be calculated by dividing the total dose given by the patient’s body weight in kilograms (kg). For example, if a patient weighs 100 lbs and received 10 mg, then their dose per kilogram would be 0.1 mg/kg because they received 10 mg divided by 100 lbs = 0.1 mg/kg. Usually this calculation is done using milligram units instead of micrograms to make it easier for nurses to use these calculations on a daily basis without having to convert them constantly or use an online decimal to fraction calculator tool

4 Dose per kilogram/hour

A dose per kilogram/hour is a calculation of milligrams (mg) or micrograms (µg), which are units of measure for the amount of active ingredient in a drug, divided by the patient’s body weight and then multiplied by 60 minutes. The result is expressed as a total amount of medicine to be administered to the patient each hour. For example, if a patient weighs 70 kilograms (154 pounds) and his/her doctor prescribes 100 mg of medication every 2 hours for 24 hours, this would equal 1400 mg/day or 14 grams per day. Dividing 1400 by 70 kilograms would yield 21 mg/kg/hour which can be converted to 21 µg/kg/min so that it can be easily expressed as “21 x 10-6 gm/(Kilogram bodyweight).

5 Dose per pound

To calculate the dose in milligrams, you must first determine the weight of your patient. To do this, weigh yourself and your patient and subtract your weight from theirs. Once you have determined their actual weight (in pounds or kilograms), multiply it by 10 to get an estimate of how many milligrams their dose should be.

If you want to convert this dosage into drops, use the following formula:

Drop Rate = (Volume of Drops x Drop Size) / Weight (in grams)

For example: If we have a patient who weighs 80 pounds and is getting 50mg/kg every 8 hours through IV push instead of continuous infusion, we would divide 50mg by 80g to get 0.625mg/g which equals an average drop rate (DR) of 0.6ml per drop given over time as opposed to all at once like with IV push!

6 Drops per ml (gtts/min)

Dose Calculation Formulas Nursing: Drops per ml (gtts/min)

The drop per ml, also known as gtt/min, is a measurement of the amount of liquid that flows out of a syringe at a certain rate. To find this value, divide the number of drops by 60 seconds.

7 Flow rate

The flow rate is the volume of liquid that passes a point in a given time. It can be measured in such units as milliliters per minute (ml/min) or milliliters per hour (ml/hr).

8 For students taking the NCLEX and other nursing exams, it is important that you are able to calculate a basic formula by hand.

For students taking the NCLEX and other nursing exams, it is important that you are able to calculate a basic formula by hand.

For example: if the patient’s temperature is 102 degrees Fahrenheit, how many milliliters of normal saline should be administered?

Answer: ______mls

Note that there are three parts to this answer. The first is an estimate of what the final concentration will be (100mL); the second part indicates how much fluid we have given (200mL); and finally, we need to know what percent of fluid remains in solution after administration (5%). If you didn’t know these values ahead of time or couldn’t remember them while administering medications then they wouldn’t matter as much since they would change depending on either volume or concentration changes due to dilution effects.


Calculating dosages is an important skill for nurses to know. The formulas are easy to memorize, but it is also important that you know how they work in order to be able to calculate them on the spot when needed.

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