Study Guide
Dosage Calculation
Rules for Rounding:

For all answers with the first number equal to or greater than 1, the answer will go to the
tenths place or one place after the decimal point. For example, 1.44 = 1.4.

For all answers with the first number of zero, the answer will go to the hundredths place
or two places after the decimal point. For example, 0.235 = 0.24.

For answers of ml/hr, whole numbers will be the appropriate answer. For example, 33.3
mls/hr = 33 mls/hr.

For rounding, if 5 or greater, round up. If less than 0-4, round down.

Any answer containing drops (gtts) will be in whole numbers.

Any answer with capsules will be in whole numbers.

Any answer with tablets can be proportioned. For example, ½ tablet, ¼ tablet.

Any answer with kgs is rounded to the hundredths place or two places after the decimal
point.
Practice Problems:
1. 36 lbs = _________kgs
2. 1.5 tsp = _________mls
3. 60mls = __________ozs
4. 26kgs =___________lbs
5. 12.5 mls =__________tsp
6. 4 ozs =____________mls
7. A child weighing 42 lbs is started on Amoxicillin. The recommended dosage is 90mg/kg/day
divided into doses BID. Answer the following 3 questions.
7a. What is the child’s weight in kilograms (round to the 2nd decimal point)?_____________kgs
7b. What is the recommended dosage per day (total daily dosage)?____________________mgs
7c. If the first dosage is given at 0700, what time should the second dosage be administered?
____________________________________________(use military time)
8, Amoxicillin 400mg/5mls is available and the patient is prescribed 600 mgs. How much
medication will be given? ____________________mls
9. Give Ranitidine 25mgs per dose PO BID. Ranitidine 15mg/1mls is available. How much
will be given per dose? __________________mls
10. Give Cetirizine 7.5 mgs. You have 5mgs/5mls available. Give _______________mls.
11. Physician orders Kantrex (kanamycin) oral suspension PO 150mg/kg/day in 2 divided doses.
Supply Kantrex 500mg/5mls. Patient’s weight: 28 lbs. How many mls should be administered
per dose? _________________mls
12. The physician orders IV fluids as follows: Infuse 1000mls of 0.45% NS solution in 10 hours
IV. Calculate the flow rate when the drop rate is 60 gtts/mls. ________________gtts/min
13. Pediaprofen (ibuprofen) 5 mg/kg po 4h for fever over 102°F. The label reads 100 mg/5 mL.
How many milliliters will you administer to a child who weighs 30 pounds? ____________mls
14. A child is to receive Morphine Sulfate 5mgs IM stat. The label reads 10mg/ml. How many
mls would you waste? ______________mls
15. Motrin (ibuprofen) 60mgs via NGT q 6 h prn pain. The label reads 40mgs/ml. How many
mls will you give?_____________________mls
16. Dr. ordered 30 mls of a medication to be administered via IV in 20 minutes. How many
mls/hr will you set the pump?______________mls/hr
17. Ceftriaxone 600mgs IM ordered. Mediation must be diluted with 5 mls to make 1gm/5mls.
How many mls will you give? __________________mls
18. Claforan (cefotaxime) 50 mg/kg/d q8h via IVF is ordered for a child who weighs 12 kg. The
label reads 50 mg/mL. How many milliliters would you withdraw from the Claforan vial to add
to the IVF? ______________________mls
19. Infuse 100 mls of 0.9% NS over 5 hours to a 6 month old child. How many mls/hr should
the IV pump be programmed for? ___________________ml/hr
20. Infuse 150 mls of D5LR over 3 hours to a 3-year-old child. How many mls/hr should the IV
pump be programmed for? ________________________ml/hr
21. Infuse 200 mls LR over 4 hours to an 8-year-old child. The tubing drip factor is 60 gtt/ml.
How many drops per minute of LR should be infused? ____________________gtt/min
22. Infuse 500mls of D5W over 8 hours to a 14-year-old child. Infusion begins at 1100. What
time will the infusion be complete? _____________________________
23. Pt is to receive Vancomycin 750 mgs IVPB q 6 hours. Medication is mixed in 200mls of
NS. Infuse over 2 hours. How fast will the infusion run? ________________________mls/hr
24. Cefdinir 600 mgs PO once a day is ordered. Tabs come 300 mgs. How many tabs will be
given? __________________tabs
25. Zofran 8 mgs PO TID is ordered. Zofran in a 100 mls bottle labeled 4 mgs/tsp is available.
How many mls will be given? __________________mls
26. At the change of shift you notice 200mls left to count in the IV bag. The IV is infusing at 80
mls/hr. How much longer will the IV run? (Express your answer in hours and minutes)
___________________________hrs minutes
27. Physician writes an order for heparin 900 units/hr. The label on the IV bag reads: Heparin
10.000 units in 500 mls D5W. How many ml/hr will deliver the correct dose?
______________ml/hr
28. An IV medication is to be given every 8 hours. You gave the first dose at 0700. When is
the next dose given? ______________________
29. A 7 year old has an order for phenobarbital 80 mg BID. Phenobarbital comes in a
concentration of 20mg/5mls. How many mls will you give? ____________________mls
30. An IV medication is to be given every 6 hours, you gave the first dose at 1400, when is the
next dose given? _________________________(use military time)
31. A 6-year-old child weighing 27 kg is to receive Methylprednisolone 4 mgs IV every 6 hours.
The drug is available in 40 mgs per ml vial. How many mls will you administer?
_____________________mls
32. Cefazolin sodium 250mgs IV every 8 hours. Reconstitute with 2.5 mls sterile normal saline.
After reconstitution the vial contains 225 mg/ml. Give __________________mls
33. Physician orders 25 mgs of Diphenhydramine (Benadryl). An ampule of Diphenhydramine
contains 50 mgs in a quantity of 1 mls. How many mls should be given? ______________mls
34. The client in labor has oxytocin (Pitocin) infusing at 10 mu/minute. She has 20 units of
Pitocin in 1000 ml of Normal Saline IV solution. If this client is receiving 10 mu /minute then
how many ml/hr would her IV infusion pump be set at?
Solutions
1. 36 lbs/ 2.2 = 16.36 kgs
2. 1.5 tsp = 7.5 mls. (1 tsp = 5 mls)
3. 60 mls = 2 ozs (30mls = 1oz)
4. 26 kgs x 2.2= 57.2 lbs
5. 12.5 mls = 2.5 tsp (5 mls = 1 tsp)
6. 4 ozs = 120mls (1 oz = 30mls)
7a. 42lbs / 2.2 = 19.09 kgs
7b. 90 mgs x 19.09 kgs = 1718.1 mgs/kg/day
7c. 1900. BID dosing is every 12 hours, if the first dose was given at 0700, the second dose is
given at 1900.
8. 400mg/5mls available, need 600mgs. 600 x 5 = 3000/400= 7.5 mls
9. 15mgs/ml available, need 25 mgs. 25 x1 = 25/15 = 1.7 mls
10. 5 mgs/5 mls available, need 7.5 mgs. 7.5 x5 =37.5/5=7.5mls
11. Convert 28 lbs to kgs. 28/2.2 =12.73kgs. 150mgs/kg = 150 x 12.73 = 1909.5 mgs per day.
1909.5/2 (BID Dosing)= 954.75mg/dose. 954.75 x5= 4773.75/500= 9.5 mls per dose
12. 1000mls/10 hrs = (1000mls/600mins) x 60gtts/min = (1000 mls/10 min) x 1 gtt/min = 100
gtt/min
13. 30lbs/2.2 = 13.63kgs. 5mg/kg = 5 x 13.63 = 68.15 mgs Have 100mgs/5mls. 68.15 mgs x5
mls=340.75 /100 =3.4 mls
14. Pt receiving 5mgs. Have 10mg/1ml. 5 x1 =5 /10 = 0.5 mls given. 1-0.5 mls = 0.5 mls
15. Give 60 mgs. Have 40 mgs/ml. 60 x1 = 60/40= 1.5 mls
16. 60 mins/20 mins= 3 x 30 = 90 mls/hr
17. Give 600mgs. Have 1g/5mls. 600 mgs x5 mls = 1000mgs xX
3000mgs/ml /1000mgs= 3
mls
18. 50 mgs x 12 kgs = 600mg/kg Have 50 mgs/ml. 600mg x 1 ml /50 mgs = 12/3 (8 hr dosing)
=4 mls per dose
19. 100mls/5 hrs = 20 mls/hr
20. 150 mls/3 hrs = 50 mls/hr
21. (200mls/240min) x 60 gtt/ml = x gtt/min
(200mls/4 min) x 1 gtt = 50 gtt/min
22. 1100 + 8 hours = 1900
23. 200 mls/2 hrs = 100 mls/hr
24. Give 600mgs, have 300 mgs tabs. 600mg/300 mgs =2. Need 2 tabs.
25. Give 8 mgs. Have 4mgs/1 tsp = 4 mgs/5 mls. 8mg x 5ml/4 mgs = 10 mls
26. 200mls/80 mls/hr = 2.5 hrs or 2 hours and 30 minutes
27. 10000 units in 500mls = 20 units/ml. Need 900 units/hr. 900units x1 mls= 900 / 20= 45
mls/hr
28. 0700 + 8 hrs = 1500
29. Give 80 mgs, have 20 mgs/5mls. 80mgs x 5 mls= 400 /20 = 20 mls.
30. 1400 +6 hrs = 2000
31. Give 4 mgs, have 40 mgs/ml. 4mgs x1 ml = 4 /40 = 0.1 mls
32. Give 250mgs, have 225mgs/ml. 250 mgs x 1ml = 250 /225 = 1.1 mls
33. Give 25 mgs, have 50 mgs/ml. 25 mgs x 1 ml= 25/50 = 0.5 mls.
34. 20 units/1000 mls = 0.02 units/ml = 0.02 units/ml x 1000 = 20 milliunits/ml
10mu/min x 60 min/ 20 mu/ml = 30 ml/hr