1. IV Calculations Basic & Advanced
Emily Kuschnereit, RN
Nursing Tutor revised fall 2009

2. Rounding in IV calc - mL
mL answers are rounded to the nearest whole mL
83.3 mL/hr rounds to 83
66.66 mL/hr rounds to 67
24.5 mL/hr rounds to 25

3. Rounding with IV calc – gtts
Round gtt calculations to the nearest whole drop –
24.5 gtts rounds to 25 gtts (drops)
13.33 gtts rounds to 13 gtts

4. Calculating ml/hr
Whenever you are given the total vol. & the total hrs. for infusion (and are asked for ml/hr), the calculation is always easy:
Total vol divided by the hrs = ml/hr
If you are given: 500 ml (any solution) to run in over 5 hrs, then
500 divided by 5 = 100 ml/hr

5. ml/hr (continued)
1 L to infuse in over 8 hrs and you are asked for ml/hr.
**** Before you divide you must convert
the L. to ml
So, 1,000 ml divided by 8 = 125 ml/hr
** 0.5 L = 500 ml L = 250 ml

6. ml/hr (continued) Why is this information important?
to assess if the IV is on time
to assure the patient receives the
correct amount of IV fluid
be able to adjust rate in a timely
manner
critical nursing skill – directly into the
body (IV route is rapid!!!)

7. ml/hr (continued) Memorize: tot vol divided by tot hrs = ml/hr
Given 500 ml to run in over 6 hr and you are asked for the ml/hr:
500 divided by 6 = 83.3 = 83
*** if 0.5 or more, round up

8. Infusion Pumps Lots of names! IV controller infusion pump IV pump
ml/hr is the information that you need to calculate, BUT some of the information SEEMS to be missing to
calculate ml/hr !

9. Pumps (continued)
Whenever you see an IV pump mentioned in your problem, think R & P
Watch:
500 ml over 10 hrs using an IV pump
500 : 10 = X : X = 50 ml/hr
** First part is your order and the second part is how you set the pump

10. Pumps (continued) Another type of problem:
50 ml (with meds) to run in over 30 min
on a IV pump.
The pump only understands 1 hr (60 min)
and the order is for a 30 min infusion!?

11. Pumps (continued) 50 ml (with meds) over 30 min on an IV pump
Order Pump
ml min = ml min
50 : = X : 60
X = 100 ml/hr ??????

12. Pumps (continued)
We trick the pump and tell it that we have 1 hr of fluid. In 30 minutes the fluid will be gone, the IV pump will alarm, and we will shut it off.
What we have done is to “translate” between the order and the pump

13. Understanding the Drop Factor (DF) –
The drop factor (DF) is the size of the
drop that is produced by the infusion set
(IV tubing) and is written on the package
of the tubing. On a written test, this
information must be given to you if you
are doing gtt/min calculations.
The drop factor (DF) may also be called:

14. Drop Factor (continued)
Other names for the drop factor:
Set calibration
Equipment delivers
Set delivers
“DF”
No matter what the name, they are the same!

15. Drop Factors (continued)
The drop factor is simply the number of drops that equal 1 ml.
DF “15” – 15 gtts = 1 ml (reg. drop)
DF “20” – 20 gtts = 1 ml (sl. sm drop)
DF “60” – 60 gtts = 1 ml (micro drop)
Do not confuse drop factor with gtts/min

16. gtts/min problems – One easy formula!!!!!
V (total vol.) X C (DF) = gtts/min
T (time in min)
*** Used for all gtts/min problems, whether greater, less, or = to one hr.

17. Gtts/min. problems Examples of types of info
Examples (greater than 1 hr):
500 ml to run in over 6 hrs, DF 15
1, ml/hr, DF 20
Examples (1 hour or less):
50 ml (with meds) over 30 min., DF 15
100 ml (with meds) over 60 min, DF 20

18. gtts/min (infusion greater than 1 hour)
Examples:
500 ml over 6 hrs., DF 15
1, ml/hr, DF 20
The formula, again is:
V X DF (C) = gtts/min (R) T

19. gtts/min (greater than 1 hr)
Watch:
500 ml over 6 hrs, DF 15
500 X = = 21 gtts/min
6x60 **
** total minutes hrs x 60 equals minutes
Round to the nearest whole drop!!!

20. gtts/min (greater than 1 hour)
Watch:
1, ml/hr, DF 20
1,000 X 20 = gtts/min
???
Your do not have hrs to calculate total
Minutes, so what do you have?
You have ml/hr – ml per 60 minutes, so

21. Gtts/min ( IV greater than 1 hr)
Watch:
100 X 20 (DF or C) = = 33 gtt/min
1x60**
** need the time in minutes, 1 hr = 60
min

22. gtts/min (less than 1 hour)
Example:
50 ml (with meds) over 30 min
DF 20
100 ml (with meds) to run in over 1
hr, DF 15

23. Gtts/min – IV less than 1 hr.
Watch:
V X DF (C) = gtts/min (R) T
50 ml to run in over 30 minutes, DF 15
50 X = = 25 gtts/min 30

24. Gtts/min – less than 1 hour
Watch:
100 ml (meds) over 1 hr, DF 20
100 X 20 = = 33 gtts/min
60 *
Remember time is in minutes 1 hr = 60 minutes

25. Time Problems Any time you are asked:
How many hrs. will this IV run? Or
If this IV 2 am, when will it
end?
These are time problems, so remember:
total vol. = # hr -- or use R & P
ml/hr

26. Time Problems
IV 500 ml 50 ml/hr. How many hours will this IV run?
500 = 10 hrs. 50
Or R & P:
50 (ml) : 1 (hr) = 500 (ml) : X (hr)
Same problem, but different info requested for answer? 500 ml
50 ml/hr. If the IV 1 am, when will it end?
Calculate hrs. as above, and then add the # of hrs. to the time ---
so add 10 hrs to 1 am and the IV will end at? 11 am

27. Time Problems
Not all time problems divide into a whole number. What do you do with a decimal (Round to the second decimal place) or fraction??
Example:
500 ml ml/hr
How many hours will this IV run?

28. Time Problems
500 ml (vol) divided by 70 (ml/hr) = 7.14 hrs (decimals are easier than fractions!)
0.14 hrs???? 14/100 of an hour??? – you need to change the decimal to minutes
0.14 hrs X 60 (min/hr) = 8.4 = 8 minutes
IV will run 7hrs. And 8 minutes
If it starts at 2 am it will end at 9:08 am

29. Types of time problems
You may be asked for either the total number of hours it will run or the time it will end:
# hrs or time it will end

30. Time Problems
If asked about the time an IV will end, pay note to whether you are asked for:
exact time – example 8:35 am
Or asked to round the nearest ½ hour or ¼ hour
8:13 am (1/4 hr) is 8:15 am
10:40 am (1/2 hr) is 10:30 am

31. Rounding with time problems
When you get an answer like
5.16 hrs - this does not mean 5 hrs
and 16 minutes
Always use the decimal hours (to the 2nd decimal place (if it is there) to calculate the minutes
0.16 X 60 = 9.6 minutes = 10 minutes
Round to the nearest whole minute

32. (mg/hr, mcg/hr. units/hr)
Advanced IV calc
Pharmacy sends 500 mg (any med) in 500 ml (any solution). The doctor ordered 120 mg/hr. How many ml an hour will this IV run?

33. Mg/hr (et al) continued
total med = ordered (med)/hr**
total vol X ml/hr **
= (mg/hr)
X (ml/hr)
X = 120 ml/hr

34. Units/hr
These problems look different, but use the same formula – watch!
25,000 units of Heparin is added to a 500
ml (any solution) to 500 units/hr
How many ml/hr will this IV run?

35. Units/hr - continued 25,000 (units) = 500 units/hr (order)
500 (ml) X ml/hr
** BOTH pieces on the right side are for the per hour amounts
X = 10 ml/hr

36. Another way to ask for info
The pharmacy adds 500 mg of a med to 1,000 mL of IV solution. The IV is to run at 50 mL/hr. How many units/hr will this IV infuse?
500 mg = X mg Note: the X
1,000 mL mL is on top

37. Another way to ask for info:
X = 25 mg/hr
If the terms mg/hr, mcg/hr, or units/hr appears in either to question or the answer, you need to do r & p and use BOTH the med and the IV fluid

38. Mg/hr, mcg/hr, unit/hr IV
These are the only IV calc problems that use BOTH the med and the IV solution -

39. One more………………..
The pharmacy adds 10,000 units of Heparin to 500 mL of IV solution. The IV is to run at 40 mL per hour. How many units per hour will infuse?
10,000 units = X units per hour
mL mL
X = 800 units/hr

40. Let’s Review 500 ml to run @ 63 ml/hr.
How many hours will this IV run:
Remember hours and minutes
(no decimals)
(7.94 – 7 hrs 56 min)

41. Review:
10,000 units in 500 ml of any solution. The order is for 1,000 units per hour.
How many ml/hr will this IV run?
50 ml/hr

42. Review 500 ml of any solution to run@40 ml/hr
The equipment delivers 20 gtts/ml.
?? How many gtts/min will this IV run?
13 gtts/min

43. Review 500 ml to run in over 10 hrs. __________ml/hr

44. Review:
500 mg of any med is added to 50 ml of any solution to run in over 30 minutes—
DF = 60.
____________gtts/min
If you have an IV pump, what is the
setting for the pump?
____________ml/hr

45. Things to remember ml/hr tot vol divided by tot hrs = ml/hr gtts/min
V X C(DF) = gtts/min (R) T
Pumps ----R & P
continued

46. Things to remember Time problems vol = # hr. ** change decimal
ml/hr to minutes (x 60)
mg/hr, mcg/hr, units/hr
R & P ----
5 types of problems
*** review selected page in your text

47. Important information
mL/hr – round to the nearest whole ml
gtts/min- round to the nearest whole drop
No decimal answers will be accepted
Memorize the formulas and use them appropriately
4 types of problems are from chapter 14 and 1 from chapter 16

48. Remember: You need to achieve at least 100 out of 125
Your first grade is the recorded grade
If you need to retest, you need to a grade of PASS on the second attempt
This grade is part of your techniques
class grade
Your answers should be identical to those
on the answer keys.

49. Things to do---- Complete the independent study
Complete assignments in the dosage calc book
Complete the practice IV calc exercises in the nursing tutor community