Clinical Calculations: Resources

Rounding Rules for Clinical Calculations

General Rules

1. If the answer is less than one (1), take the math out three (3) places past the decimal point (the thousandth position) and round to two (2) places past the decimal point (the hundredth position).
2. If the answer is greater than one (1), take the math out two (2) places past the decimal point (the hundredth position) and round to one (1) place past the decimal point (the tenth position).
3. Do not include trailing zeros. (Ex: 12.0 ml would simply be expressed as 12 ml and 0.40 mg would be expressed as 0.4 mg)
4. Always use a leading zero for numbers less than one. (Ex: .25ml should be expressed as 0.25ml)
5. Be careful not to round until the end of the problem. Rounding early in the problem results in at least double rounding and will give you an incorrect answer in the end. (Ex: if converting weight from pounds to kgs before working out the rest of the problem, leave the math expressed as three (3) places past the decimal point until after the rest of the problem is worked out)

Rules for Tablets and Capsules

1. For tablets, if you have a problem that works out to exactly 0.5 tablet, do not round your answer. If the answer works out to less than 0.5 tablet, round down to the next whole number. If the answer works out to greater than 0.5 tablet, round up to the next whole number.
2. Capsules are different. You cannot give a part of a capsule. Therefore, capsules have to be rounded to a whole number. Less than half a capsule rounds down to the next lowest whole number. A half capsule and greater rounds up to the next whole number.

Rules for IV Problems

1. For IV fluids being administered by gravity (drops per min), the number of drops must be expressed as a whole number. Therefore, you would round to the nearest whole drop. (Ex: 34.5 = 35gtts/min, 38.4=38gtts/min)

    

2. For IV fluids being administered by an infusion pump (ml/hr), the number of ml to be infused each hour is to be expressed as a whole number. Therefore, you would round to the nearest whole ml.

    

3. If you are told in the problem that you have a micropump for the IV fluid infusion, take the math out two (2) places past the decimal point and round to the first place past the decimal point (the tenths position).

    

4. When calculating how long it will take IV fluids to infuse, you are to express your answer in hours and minutes. Be sure to take the math out three (3) places past the decimal point before converting the partial hour to minutes. (Ex: 4.462 hours where 0.462 x 60 = 27.72 = 28mins for a final answer of 4hrs 28mins.

    

Commonly Used Equivalents

Weight Measurements

1 kg (kilogram) = 1000g (Note: g, G, Gm, gm are all abbreviations for gram)

1 g (gram) = 1000 mg (milligrams)

1 mg (milligram) = 1000 mcg (micrograms)

1 kg (kilogram) = 2.2 lb (pounds)

16 oz (ounces) = 1 lb (pound)

Volume Measurements

5 ml (cc) (milliliters, cubic centimeters) = 1 tsp (teaspoon)

3 tsp (teaspoons) = 1 Tbsp (tablespoon)

30 ml (cc) (milliliters, cubic centimeters) = 1 oz (ounce)

2 Tbsp (tablespoons) = 1 oz (ounce)

8 oz (ounces) = 1 cup

16 oz (ounces) = 1 pt (pint)

2 pt (pint) = 1 qt (quart)

1000 ml (milliliters) = 1 L (liter)

1 qt (quart) = 32 oz (ounces)

Length Measurements

10 mm (millimeters) = 1 cm (centimeter)

2.5 cm (centimeters) = 1 inch