General Rules:

  • Spell out numbers one through nine; use figures for 10 or above.

    • Exception: Always use figures for numerals preceding units of measure; ages of people, animals, events or things; and all tabular and statistical data. Additional exceptions are discussed in the sections that follow.
  • Do not make two sets of numbers parallel by breaking the normal construction.
    • Correct: There were five boys and 11 girls.
    • Incorrect: There were 5 boys and 11 girls.


Ages


Rule: Always use figures for ages. When “years” or “years old” are not required within the context, the figure for ages is assumed to be years.
    • The house is 10 years old.
    • Her daughter is 17.
    • His son is 2 years old.
Rule: Use hyphens for compound adjectives in front of nouns or used as substitutes for nouns.
  • The doctor has a 3-year-old girl (adjective before a noun).
  • The medication is approved for 2-year-olds.


Beginning a Sentence


Rule: Spell out numerals at the beginning of a sentence. The only exception is numerals identifying a calendar year.

    • Correct: Last semester, 898 new freshmen attended the college.
    • Correct: 2012 saw the highest amount spent on presidential elections in history.
    • Incorrect: 898 new freshmen attended the college last semester.


Decimal Units


Rule: Decimal units are shown with numerals and a period. Do not exceed two decimal places in text unless there is a special circumstance.
    • 15.37 cubic feet
    • 35.35 meters
    • 6.3 kilometers


Rule: For amounts less than 1, use a numerical 0 in front of the decimal point, and keep the measurement type singular.

  • 0.75 cubic foot
  • 0.45 meter
  • 0.90 kilometer


Degrees of Temperature


Rule: Use figures for all temperatures except zero. For temps below zero, use a word, not the minus sign.

  • The low yesterday was minus 11.
  • Yesterday’s low was 11 below zero.
  • 8-degree temperatures
  • temperatures fell 8 degrees
  • temperatures in the 20s (no apostrophe)

Rule: Temperatures never get “warmer” or “cooler”; they get higher or lower.

  • Correct: Temperatures during the day are rising.
  • Correct: Temperatures during the day are getting higher.
  • Incorrect: Temperatures are getting warmer during the day.

Celsius and Fahrenheit

Rule: When the scales are required, use “degrees Celsius” or "degrees Fahrenheit." 


Rule: When the degrees and scale are clear, use “C” or "F" with a space between the figure and the C or F and no period for the abbreviation.

  • 37 degrees Celsius or 37 C
  • 78 degrees Fahrenheit or 78 F


Dimensions


Rule: Use figures, and spell out the unit of measurement for depth, height, length and width. 


Rule: For adjectival forms in front of nouns, use hyphens.

  • She is 5 feet 8 inches tall.
  • The 5-foot-8-inch girl...
  • The 5-foot girl...
  • The crawl space is 16 feet long, 8 feet wide and 4 feet high.
  • The bedroom is 10 feet by 13 feet.
  • The 10-by-13 bedroom...
  • Last night 8 inches of snow fell.
Rule: The apostrophe to notate feet and quotation mark to notate inches (5’8”) is only used in context that is very technical in nature.


Distances


Rule: Use numerals for distances.

  • She runs 5 miles daily.
  • She walks a total of 20 miles every week.


Fractions


Amounts less than 1

Rule: Spell out with hyphens between words.

  • one-eighth
  • one-fourth
  • two-thirds
  • seven-sixteenths


With mixed numbers

Rule: Use a full space between the whole number and the fraction.

  • 1 ½
  • 12 ⅞


Monetary Units


Cents

Rule: Spell the word “cents” in all lowercase, and use it with figures and no dollar sign for amounts less than a dollar.

  • 7 cents
  • 89 cents

Rule: For amounts larger than a dollar, use the decimal form and dollar sign.

  • $1.05
  • $2.12


Dollars

Rule: Use the dollar sign and figures unless it’s a casual reference or an amount without a figure.

  • The game cost $15.
  • Please give her a dollar.
  • Dollars saved add up over time.


Less than $1 million

Rule: Use figures with dollar signs and appropriate commas.

  • $6
  • $30
  • $400
  • $2,000
  • $780,000


More than $1 million

Rule: Use two decimal places, and omit hyphens between a figure and a word.

  • The company is worth $5.45 million.
  • The company is worth exactly $5,452,393.
  • The company proposed a $200 million budget.

Ordinals


Rule: Ordinals are numbers used to indicate order (first, second, 10th, 25th, etc.). 

 

Rule: Spell out first through ninth. Use figures starting with 10th.

 

  • Example: The boy is in fourth grade.

  • Example:  Peas are the 11th item on my grocery list.


Percent


Rule: Percent is one word, not two.


Rule: Use figures. For partial numbers, use decimals, not fractions.

  • 1 percent
  • 3.5 percent
  • 11 percent
  • 3 percentage points


Rule: Use a zero in front of the decimal for percentages less than 1.

  • Profits only rose 0.8 percent over the first quarter.


Ranges


Rule: Use “to” between the figures, or use between/and.

  • 11 to 14 percent
  • between 11 and 14 children


Proportions


Rule: Always use figures for proportions.

  • Use 2 parts cement to 1 part water.


Speeds


Rule: Always use figures for speeds.

  • The car was only moving at 10 mph.
  • winds of 10 to 15 mph
  • 10-mph wind


Note: Aim to avoid constructions that require extensive hyphens.

  • Correct: 8-mph winds
  • Incorrect: 8-mile-per-hour winds


Weights


Rule: Use figures for all weights, and spell out the unit of measurement. Hyphenate when the weight is in adjectival form before the noun.

  • The can weighs 2 pounds, 8 ounces.
  • the 2-pound, 8-ounce can