1. Dosage Calculation
Pro Calc Nursing 131

2. Calculating dosage in tabs, caps, ml
This tutorial demonstrates calculating the number of tablets, capsules, or milliliters to prepare. Our first example: 35mg of Sinequan(Doxepin) has been prescribed po. How many ml should you administer if the Sinequan is available in a strength labeled 10 mg in 1 ml?

3. Calculating dosage in tabs, caps, ml
Step One – Write down the dosage you want to administer.
Step Two – Write down the known strength.
Step Three – Reduce the units.
Step Four – Perform the math.

4. Calculating dosage in tabs, caps, ml
Our first example: 35mg of Sinequan(Doxepin) has been prescribed po. How many ml should you administer if the Sinequan is available in a strength labeled 10 mg in 1 ml?
Step One – Write down the dosage you want to administer.
In our example, we want to administer 35 mg.
We’ll write this as a fraction with a denominator of 1.
35 mg 1

5. Calculating dosage in tabs, caps, ml
Our first example: 35mg of Sinequan(Doxepin) has been prescribed po. How many ml should you administer if the Sinequan is available in a strength labeled 10 mg in 1 ml?
Step Two – Write down the known strength.
In our example, the strength is 10mg in 1 ml.
We can write this strength two ways.
1 ml
10 mg
10 mg
1 ml or
Since the fraction we wrote in step one has mg on the top, our next fraction needs to have mg on the bottom.
(Step One)
35 mg 1
(Step Two)
1 ml
10 mg

6. Calculating dosage in tabs, caps, ml
Step Three – Reduce the units.
Cross off any matching pairs of unit labels. The label left should be what you want to find.
(Step One)
35 mg 1
(Step Two)
1 ml
10 mg
In this example the only unit left is ml which is what we want to find.

7. Calculating dosage in tabs, caps, ml
(Step One)
35 mg 1
(Step Two)
1 ml
10 mg
Step Four – Perform the math.
35 x 1 35 =
Reduce any fractions and remember the units label.
1 x 10 10
= ml
Our first example: 35mg of Sinequan(Doxepin) has been prescribed po. How many ml should you administer if the Sinequan is available in a strength labeled 10 mg in 1 ml?
We have found that we to need administer 3.5 ml of Sinequan.

8. Calculating dosage in tabs, caps, ml
Our second example: mg of Keflex (Cephalexin) has been prescribed mg of Keflex is available in capsules. How many capsules should be administered?
Step One – Write down the dosage you want to administer.
In our example, we want to administer 500 mg.
We’ll write this as a fraction with a denominator of 1.
500 mg 1

9. Calculating dosage in tabs, caps, ml
Our second example: mg of Keflex (Cephalexin) has been prescribed mg of Keflex is available in capsules. How many capsules should be administered?
Step Two – Write down the known strength.
In our example, the strength is 250 mg in 1 capsule.
We can write this strength two ways.
250 mg
1 capsule or
1 capsule
250 mg
(Step One)
500 mg 1
(Step Two)
1 capsule
250 mg
Since the fraction we wrote in step one has mg on the top, our next fraction needs to have mg on the bottom.

10. Calculating dosage in tabs, caps, ml
Step Three – Reduce the units.
Cross off any matching pairs of unit labels. The label left should be what you want to find.
(Step One)
500 mg 1
(Step Two)
1 capsule
250 mg
In this example the only unit left is capsules which is what we want to find.

11. Calculating dosage in tabs, caps, ml
(Step One)
500 mg 1
(Step Two)
1 capsule
250 mg
Step Four – Perform the math. X
500 x 1
500 capsules =
Reduce any fractions and remember the units label.
1 x 250
250
= 2 capsules
Our second example: mg of Keflex (Cephalexin) has been prescribed mg of Keflex is available in capsules. How many capsules should be administered?
We have found that we need to administer 2 capsules of Keflex.

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