Dosage Calculation
3008A: Professional Nursing
Transition
Michelle Rector, RN
Lecture Objectives
• Memorize equivalents, drop factors, roman numerals, and abbreviations.
• Convert conventional time to continental time.
• Calculate and convert dosages within the same equivalent system and
from one system of measurement to another system of measurement.
• Calculate oral, intramuscular, and subcutaneous dosages for
administration of medications.
• Calculate the flow rate of intravenous fluids in ml/hr and gtt/min.
• Calculate the infusion time of a prescribed intravenous fluid in hours.
Reading Assignment
Curren Ch. 4 – 5, 13, and 17 – 18.
Rules to Remember
• Always put a zero in front of your decimal.
• Use only approved abbreviations.
• When in doubt ask!
Abbreviations
lb = pound
dr = dram
t or tsp = teaspoon
mg = milligram
m = minim
kg = kilogram
in = inch
cm = centimeter
a.c. = before meals
hs = at bedtime
IV = intravenous
PRN = as necessary
oz = ounce
tbsp or T = tablespoon
Gr or gr = grain
gm or g = gram
C = cup
ml or mL = milliliter
mm = millimeter
L = liter
fl oz = fluid oz
elix = elixir
IM = intramuscular
NS = normal saline
fl dr = fluid dram
cc = cubic centimeter
mcg = microgram
po = by mouth
M = meter
qt = quart
pt = pint
ft = foot
Yd = yard
Roman Numerals
• V = five
• X = ten
Drop Factors
Standard IV Tubing = 15gtt/ml
Microdrip IV tubing = 60 gtt/ml
Blood set tubing = 10 gtt/ml
Note: drop factor will be on your tubing package.
Equivalents
Solids
1 lb= 16 oz
2.2 lb = 1 kg
1 kg = 1000 gm
1000 mcg = 1 mg
1000 mg = 1 gm = 15 gr
60 mg = 1 gr
8 dr = 1 oz
Equivalents
Length
12 in = 1 ft
1000 mm = 100 cm = 1 M
2.5 cm = 1 in
3 ft = 1 Yd
Equivalents
Liquids
1 gtt = 1 m
1 ml = 1 cc
15 gtt or m = 1 ml = 1 cc
1 fl dram = 4 ml
1 fl dram = 60 m
1 tsp = 5 ml
3 tsp = 1 T
Equivalents
Liquids
continued
1 T or tbsp = 15 ml or 1 fl oz = 30 ml = 2 T
1000 ml = 1 L = 1 qt
1 glass or cup = 8 oz (240 ml)
8 dr = 1 oz
1 pt = 16 oz = 2 cups
1 qt = 32 oz = 2 pt
1 gal = 4 qt
Conventional & Continental (military)
Time
• The time is based on a 24 hr clock.
• Begin @ 1 am or 0100 and end @ 12
midnight or 2400.
• Start over @ 2400 using 0001 @ 1201 am.
12: 01 AM
1:00 AM
2:00 AM
3:00 AM
4:00 AM
5:00 AM
6:00 AM
7:00 AM
8:00 AM
9:00 AM
10:00 AM
11:00 AM
= 0001
= 0100
= 0200
= 0300
= 0400
= 0500
= 0600
= 0700
= 0800
= 0900
= 1000
= 1100
12 noon = 1200
1:00 PM = 1300
2:00 PM = 1400
3:00 PM = 1500
4:00 PM = 1600
5:00 PM = 1700
6:00 PM = 1800
7:00 PM = 1900
8:00 PM = 2000
9:00 PM = 2100
10:00 PM = 2200
11:00 PM = 2300
12 midnight = 2400
Rounding Rules
•
•
•
•
scored tablet
cc or ml to administer
gtt
cc or ml IV
= half
= tenth
= whole
= whole *
* As a student progresses through the curriculum and principles of
pharmacology are introduced, some of the rounding rules may not be
clinically appropriate.