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Nursing math · Printable chart

Nursing conversions chart

The conversions nursing programs expect you to know, on one printable page: metric and household units, pounds to kilograms, inches to centimeters, the Celsius and Fahrenheit formulas, apothecary grains, Roman numerals and military time. Then worked examples and 20 practice problems that check your typed answer and show every step. Free, and for study only.

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  • Worked examples
  • 20 practice problems
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Part 1 · The chart

Nursing conversions chart

The equivalents nursing programs ask you to memorize, the formulas behind them, and the exact figure beside each rounded one. Print it as it is: only the chart goes on paper.

Metric prefixes: King Henry Died Drinking Chocolate Milk

Each step is ×10. Kilo- is the big end; milli- is the small end.

PrefixSymbolMeansMnemonic
kilo-k1,000King
hecto-h100Henry
deka-da10Died
base unitg, L, m1(By)
deci-d0.1Drinking
centi-c0.01Chocolate
milli-m0.001Milk
  • Each step on the ladder is ×10. Moving to a smaller unit moves the decimal to the right; moving to a larger unit moves it to the left. [1]
  • The six-word mnemonic skips the base unit, which sits between “Died” and “Drinking”. Some classes add a word for it: “King Henry Died By Drinking Chocolate Milk”.
  • Micro- (mcg) is three more places below milli-: 1 mg = 1,000 mcg. Write mcg, never µg, which has been misread as mg. [1] [9]

Metric equivalents

Weight in grams, volume in liters, length in meters. Every step is a factor of 1,000 or 100.

UnitEquals
1 kg (kilogram)1,000 g
1 g (gram)1,000 mg
1 mg (milligram)1,000 mcg
1 L (liter)1,000 mL
1 mL (milliliter)1 ccThe same volume; write mL. [4] [9]
1 m (meter)100 cm
1 cm (centimeter)10 mm

Household to metric

The rounded figures dosage charts use, with the exact value beside each.

Household unitMetric equivalent
1 tsp (teaspoon)5 mLexact: 4.93 mL
1 Tbsp (tablespoon)3 tsp = 15 mLexact: 14.79 mL
1 fl oz (fluid ounce)2 Tbsp = 30 mLexact: 29.57 mL
1 cup8 oz = 240 mLexact: 236.6 mL
1 pt (pint)2 cups = 16 oz480 mL by the 240-mL cup; many nursing charts list 500 mL; exact: 473 mL
1 qt (quart)4 cups = 2 pt960 mL by the 240-mL cup; many nursing charts list 1,000 mL (1 L); exact: 946 mL
1 gal (gallon)4 qt
1 gtt (drop)not a fixed sizeIV tubing is rated 10, 12, 15 or 20 gtt per mL; microdrip tubing gives 60 microdrops (mcgtt) per mL.

Weight: pounds and kilograms

UnitEquals
1 kg2.2 lbexact: 1 lb = 0.4536 kg
1 lb (pound)16 oz
1 oz (ounce, weight)about 28.35 g
lb → kgdivide by 2.2
kg → lbmultiply by 2.2
  • 90 lb40.9 kg
  • 100 lb45.5 kg
  • 110 lb50 kg
  • 120 lb54.5 kg
  • 130 lb59.1 kg
  • 140 lb63.6 kg
  • 150 lb68.2 kg
  • 160 lb72.7 kg
  • 170 lb77.3 kg
  • 180 lb81.8 kg
  • 190 lb86.4 kg
  • 200 lb90.9 kg
  • 210 lb95.5 kg
  • 220 lb100 kg
  • 230 lb104.5 kg
  • 240 lb109.1 kg
  • The quick table divides by 2.2 and rounds to the nearest tenth. The exact factor (0.4536) runs slightly lower: 150 lb is 68.2 kg by 2.2 and 68.0 kg exactly.
  • Carry the decimals through and round only at the end, the way your program’s rules say.

Length: inches and centimeters

UnitEquals
1 in (inch)2.54 cmexact, by definition
1 cmabout 0.39 in
1 ft (foot)12 in
in → cmmultiply by 2.54
cm → individe by 2.54

Temperature: Celsius and Fahrenheit

The two formulas, then a quick table for the range a thermometer reads.

Celsius to Fahrenheit
°F = (°C × 1.8) + 32
1.8 is the same as 9 ÷ 5
Fahrenheit to Celsius
°C = (°F − 32) ÷ 1.8
subtract 32 first, then divide (or × 5 ÷ 9)
CelsiusFahrenheit
37 °C98.6 °F
0 °C32 °F
100 °C212 °F
  • 35.0 °C95.0 °F
  • 35.5 °C95.9 °F
  • 36.0 °C96.8 °F
  • 36.5 °C97.7 °F
  • 37.0 °C98.6 °F
  • 37.5 °C99.5 °F
  • 38.0 °C100.4 °F
  • 38.5 °C101.3 °F
  • 39.0 °C102.2 °F
  • 39.5 °C103.1 °F
  • 40.0 °C104.0 °F
  • 40.5 °C104.9 °F
  • 41.0 °C105.8 °F

Apothecary equivalents (legacy)

Older units you still meet on some orders and in course materials. Approximate by nature.

Apothecary unitEquals
gr i (1 grain)60 mgthe nursing convention; some charts use 65 mg; the exact value is 64.8 mg
gr xv (15 grains)about 1 gcharts list 1 g even though 15 × 60 mg is 900 mg; the exact value is 972 mg
1 dram (dr)60 grains
1 oz (apothecary weight)8 drams
1 fl dram (fl dr)about 4 to 5 mLone eighth of a fluid ounce; exact: 3.7 mL
1 fl oz8 fl drams
1 pt16 fl oz
1 qt2 pt
1 gal4 qt
  • Rarely used now: ISMP recommends metric for medicines, and the FDA recommends mL for liquid ones. You still meet it on older orders and in course materials. [4]
  • The amount comes after the unit and is written as a lowercase Roman numeral, with ss for a half: gr v, gr iss, gr ss. [6] [7]
  • Because the equivalents are rounded, convert an apothecary or household amount to metric once, with the figure your program gives, and do the math in metric. [7]

Roman numerals

Used with apothecary units and on some orders and labels.

  • I1
  • V5
  • X10
  • L50
  • C100
  • D500
  • M1,000
  1. 1I
  2. 2II
  3. 3III
  4. 4IV
  5. 5V
  6. 6VI
  7. 7VII
  8. 8VIII
  9. 9IX
  10. 10X
  11. 11XI
  12. 12XII
  13. 13XIII
  14. 14XIV
  15. 15XV
  16. 16XVI
  17. 17XVII
  18. 18XVIII
  19. 19XIX
  20. 20XX
  21. 21XXI
  22. 22XXII
  23. 23XXIII
  24. 24XXIV
  25. 25XXV
  26. 26XXVI
  27. 27XXVII
  28. 28XXVIII
  29. 29XXIX
  30. 30XXX
  31. 40XL
  32. 50L
  33. 60LX
  34. 70LXX
  35. 80LXXX
  36. 90XC
  37. 100C
  38. 400CD
  39. 500D
  40. 900CM
  41. 1,000M
  • Add the values when the letters are the same or run from larger to smaller: XX = 20, VIII = 8, MCCLXXXVIII = 1,288.
  • A smaller letter to the left of a larger one is subtracted from it: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900.
  • No letter repeats more than three times in a row, which is why 4 is IV, not IIII, and 40 is XL.
  • Upper or lower case both count. In pharmacology, s or ss stands for one half (gr iss = 1½ grains).

Military time (24-hour clock)

How medicine times are charted: 0700 and 1900 instead of 7 AM and 7 PM.

Standard time and military time, on the hour
Standard24-hourStandard24-hour
12:00 AM000012:00 PM1200
1:00 AM01001:00 PM1300
2:00 AM02002:00 PM1400
3:00 AM03003:00 PM1500
4:00 AM04004:00 PM1600
5:00 AM05005:00 PM1700
6:00 AM06006:00 PM1800
7:00 AM07007:00 PM1900
8:00 AM08008:00 PM2000
9:00 AM09009:00 PM2100
10:00 AM100010:00 PM2200
11:00 AM110011:00 PM2300
  • Four digits, no colon, no AM or PM: hours first, then minutes.
  • An AM time drops the colon and gains a leading zero when the hour has one digit: 6:30 AM = 0630, 11:15 AM = 1115.
  • A PM time drops the colon and adds 1200: 7:15 PM = 1915, 3:45 PM = 1545.
  • Midnight starts the day at 0000 and noon is 1200, so 12:30 AM = 0030 and 12:30 PM = 1230. Your charting rules decide the details, such as whether the last minute of the day is 2359.

Other measures you will see

Not conversions, but they sit on the same orders.

MeasureWhat it is
unitfor insulin, heparin and some other medicinesWrite the word “unit”, never U, which has been read as 0 or 4. [8]
International Unitfor some vitaminsWrite it out; IU has been read as IV or 10. [8]
mEq (milliequivalent)for electrolytessuch as potassium or sodium replacements
0.9 % (a percentage)0.9 g in every 100 mLso a liter of 0.9 % sodium chloride holds 9 g
1:1,000 (a ratio)1 g in 1,000 mL

Write the figure so it cannot be misread

The Joint Commission and ISMP rules that go with every conversion.

CaseWrite
A decimal below one0.5 mg, never .5 mgthe missing leading zero turns 0.5 into 5
A whole number5 mg, never 5.0 mgin a medication order the trailing zero turns 5 into 50; a trailing zero belongs only where it shows precision, such as a lab result or a tube size
Microgramsmcg, never µg
MillilitersmL, never cc
Unitsunit, never U

Part 2 · How to convert

How to convert, step by step

The same four moves solve every problem on this page. Then one worked example for each kind of conversion, with every step shown.

  1. Rule 1

    Start from the equivalent you know

    Every conversion on the chart is one fact, such as 1 kg = 2.2 lb or 1 tsp = 5 mL. Write that fact down first; the arithmetic follows from it.

  2. Rule 2

    Let the units tell you whether to multiply or divide

    Going to a smaller unit (grams to milligrams, kilograms to pounds) makes the number bigger, so you multiply. Going to a larger unit (milligrams to grams, pounds to kilograms) makes the number smaller, so you divide. If your answer went the wrong way, the setup was upside down.

  3. Rule 3

    Inside the metric system, just move the decimal

    A step of 1,000 is three places: 0.25 g is 250 mg, and 500 mcg is 0.5 mg. Count the places on the prefix ladder rather than reaching for a calculator.

  4. Rule 4

    Round at the end, and write it safely

    Keep the decimals through the work and round once, to the place your program asks for. Then write a leading zero before any decimal (0.5 mg) and never a trailing zero after a whole number (5 mg, not 5.0 mg).

Worked examples

  1. Example 1

    Convert 0.75 g to milligrams.

    1. Milligrams are the smaller unit, so the number gets bigger: multiply by 1,000, which moves the decimal three places to the right.
    2. 0.75 g × 1,000 = 750 mg

    Answer: 750 mg

  2. Example 2

    Convert 250 mcg to milligrams.

    1. Milligrams are the larger unit, so the number gets smaller: divide by 1,000, which moves the decimal three places to the left.
    2. 250 mcg ÷ 1,000 = 0.25 mg
    3. Write the leading zero: 0.25 mg, never .25 mg.

    Answer: 0.25 mg

  3. Example 3

    Convert 165 lb to kilograms.

    1. 1 kg = 2.2 lb, so divide the pounds by 2.2.
    2. 165 ÷ 2.2 = 75
    3. Check: a kilogram is heavier than a pound, so the number of kilograms is always the smaller number.

    Answer: 75 kg

  4. Example 4

    Convert 8 fl oz to milliliters.

    1. 1 fl oz = 30 mL on the nursing chart (the exact figure is 29.57 mL; dosage charts use 30).
    2. 8 × 30 = 240 mL

    Answer: 240 mL

  5. Example 5

    Convert 37.8 °C to Fahrenheit.

    1. Multiply the Celsius figure by 1.8 (the same as 9 ÷ 5), then add 32.
    2. 37.8 × 1.8 = 68.04
    3. 68.04 + 32 = 100.04
    4. Rounded to the nearest tenth: 100.0 °F

    Answer: 100.0 °F

  6. Example 6

    Convert 102.2 °F to Celsius.

    1. Subtract 32 first, then divide by 1.8 (the same as multiplying by 5 ÷ 9).
    2. 102.2 − 32 = 70.2
    3. 70.2 ÷ 1.8 = 39

    Answer: 39.0 °C

  7. Example 7

    Convert 70 in to centimeters.

    1. 1 in = 2.54 cm exactly, so multiply the inches by 2.54.
    2. 70 × 2.54 = 177.8

    Answer: 177.8 cm

  8. Example 8

    Write 7:15 PM in military time.

    1. A PM time drops the colon and adds 1200.
    2. 7:15 PM → 715 + 1200 = 1915
    3. Four digits, no colon, no AM or PM.

    Answer: 1915

  9. Example 9

    Write 24 in Roman numerals.

    1. Break 24 into Roman values, largest first: 10 + 10 + 4
    2. 10 = X
    3. 10 = X
    4. 4 = IV
    5. A value with a 4 or a 9 is written by subtraction, because no letter repeats more than three times.
    6. Put them together: XXIV

    Answer: XXIV

  10. Example 10

    Using gr i = 60 mg, convert gr iss to milligrams.

    1. gr iss means 1.5 grains (ss is one half).
    2. Nursing charts use 1 grain = 60 mg. The exact value is 64.8 mg and some charts round to 65 mg, so use the figure your program gives.
    3. 1.5 × 60 = 90 mg

    Answer: 90 mg

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Part 3 · Practice problems

20 practice problems, checked step by step

Type your answer and check it. Right or wrong, every problem shows its steps, and your score at the end is free. Metric steps, pounds and kilograms, household volumes, temperature, length, military time, Roman numerals and grains.

Problem 1 of 20

Convert 0.5 g to milligrams.

Type the number only; the unit is mg.

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Sources

Where the figures come from

Everything here is written in our own words from these public sources. Where a figure is rounded, the exact one is beside it; where sources differ, the chart says so and your program’s figure comes first.

Questions

Common questions

Multiply the Celsius temperature by 1.8 (the same as 9 ÷ 5) and add 32: °F = (°C × 1.8) + 32. For 38.5 °C that is 38.5 × 1.8 = 69.3, plus 32 = 101.3 °F. The other way, subtract 32 first and then divide by 1.8: °C = (°F − 32) ÷ 1.8, so 100.4 °F is 68.4 ÷ 1.8 = 38 °C. The anchor to remember is 37 °C = 98.6 °F.

On the nursing chart, 1 teaspoon = 5 mL, 1 tablespoon = 3 teaspoons = 15 mL, and 1 fluid ounce = 2 tablespoons = 30 mL. Those are rounded: the exact US figures are 4.93 mL, 14.79 mL and 29.57 mL. Dosage charts and course materials use the rounded ones, and that is what the practice problems here expect.

Divide the pounds by 2.2, because 1 kg = 2.2 lb: 154 lb ÷ 2.2 = 70 kg. To go the other way, multiply the kilograms by 2.2. A quick check: the number of kilograms is always the smaller of the two. The exact factor is 1 lb = 0.4536 kg; 2.2 is the rounded version nursing texts use.

The metric prefixes in order from large to small: kilo- (1,000), hecto- (100), deka- (10), then the base unit (gram, liter or meter), then deci- (0.1), centi- (0.01) and milli- (0.001). Each step is ×10, so converting is a matter of moving the decimal point. The six-word version skips the base unit, which sits between “Died” and “Drinking”; some classes say “King Henry Died By Drinking Chocolate Milk” to name it. Micro- (mcg) is three more places past milli-: 1 mg = 1,000 mcg.

Four digits, no colon, no AM or PM. An AM time drops the colon and takes a leading zero if the hour has one digit (6:30 AM = 0630). A PM time drops the colon and adds 1200 (7:15 PM = 1915). Midnight starts the day at 0000 and noon is 1200. Medicine times are charted this way so that 7 AM and 7 PM cannot be mixed up.

Because the grain is an old unit and the equivalents are rounded. The exact value is 64.8 mg; many nursing programs teach 60 mg, some teach 65 mg, and 15 grains is usually taken as 1 g (exactly 972 mg). This page and its practice problems use gr i = 60 mg and say so in each question. Use the figure your program gives, and convert to metric once rather than working in grains.

No. It is a chart to learn from and a set of practice problems to work by hand. The practice boxes only compare what you type with the problem’s own answer and then show the steps, because doing the conversion yourself is what a dosage-calculation course asks of you.

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No. Everything on this page is for study. It does not calculate, check or recommend a dose for anyone, and nothing about a patient is typed in. With a real order, your facility’s policy, its references and your instructor come first.