Using numbers in contracts and using formulae are a matter of style. A very old-fashion way of expressing numbers in contracts is to write both the number and the figure between brackets (or vice versa). This paragraph will explain that this is exaggerated and not without risk. It will first address numbers, ranges, and then cover formulae.

Best practices of numbers in contracts

For identifying and finetuning the principles, I have relied on two important sources: the English Style Guide of the European Commission and the online version of The Economist Style Guide[1].

If a transaction amounts to many numbers, collect them in one single spreadsheet and double check whether they all came over. In order to avoid mistakes, it is recommended that one person in the team takes responsibility for the economics and delivers to the drafter any subsequently changing overviews of proposed or agreed amounts. If numbers will likely change, or if they are not for everyone’s eyes, keep them out of the first draft versions.

To explain the principles in this paragraph, I will refer to numbers (i.e., disregarding their being expressed as a figure or in words), to figures (e.g., 1; 12; 78; 1,250; 1,563,465) or in words (e.g., three; one million).

1) Be rigorously consistent in the use of figures or words to express a figure.

If a provision or contract contains both figures and words, use either figures or words for all the numbers of the same category. Realise that generally, a reader comprehends figures more readily than their being reflected in words[1]. Examples:

  • Each of 15 major commodities (9 metal and 6 non-metal) was in supply.
  • but Each of nine major commodities (five metal and four non-metal) was in supply.
  • Petroleum came from 16 fields, of which 8 were discovered in 1956.
  • but Petroleum came from nine fields, of which eight were discovered in 1956.

Many US-based contract drafters prefer, however, to exclude the main figure or figures in all cases from this consistency principle, such as a purchase price, an investment or a loan principal. Such amounts might be written out in both figures and words for emphasis or certainty. In such case, do not spell out the decimals (if any). For example:

The purchase price for the Shares is EUR 697,345.45 (six hundred ninety-seven three hundred forty-five euro and 45 cent), adjusted in accordance with Article 4.

The background of this is to increase certainty: by writing a number both in figures and in words, people believe that if a misprint (of the figure) appears in the final version, its expression in words should clarify what was actually agreed. On the other hand, realise that if the numbers change during discussions or negotiations, it seems (much) more likely that the figures are properly updated whilst the parties overlook the words. There are computer applications automatically updating figures (what do you need the words for then?); there are usually several persons involved in a contract (do they focus on the figures?).

Does any legal system reward typos over what was actually agreed[2]? In all cases, the files or background explanation would then provide the inevitable solution to what was in fact agreed. Since such file or explanation provides the key to the solution and because the chance of faults during a figure-update appears larger than the chance of a misspelling in the figure itself, writing a number in both figures and words seems to create a false certainty. This is why using both is discouraged here.

Clarification may nevertheless be desirable in the case of 0 (zero), or if a number in a contract clause is a remarkably low one (e.g., as in “the purchase price for the Shares is EUR 1 (one euro)”) without any clarifying or otherwise justifying context.

For obvious reasons, never change a name that includes a number.

2) Use words for simple figures from one to ten. Use figures for numerals from 11 upwards and for all figures that include a decimal point or a fraction.


  • One, seven, 14, 975 and 6,650
  • 4.25 and 4¼
  • During the initial three years of the Term, Purchaser shall order at least 4, 8 and 21 yachts, respectively.

It may occasionally be desirable to write out round numbers up to twenty, if this would be defended in view of consistency. (All these numbers have a unique spelling that is no case the result of compounding two written-out numbers). The shift to all-figures should then be made only if one figure above twenty appears.

Do not print Roman numerals in small-capitals (but either in underscores or capitals). Note that Arabic numerals are preferable to Roman ones.

3)     Always use figures in percentages, for cross references and serial numbers, for ranges denoted by a dash, in tables, for statistics and for votes.


  • Percentages: 4 percent;
  • Cross references and serial numbers: page 25, Article 9, Section 3, Part 2;
  • Ranges denoted by a dash: sections 3.14 to 3.15;
  • Statistics: 3 managing directors were appointed in 2008, 2 in 2009…; and
  • Votes: 6 members were in favour, 3 against, and 2 abstained.

Avoid starting a sentence with a figure; otherwise, write the number in words instead. If this does not work, try devices such as inversion:

  • Another 75 percent of the Principal Amount shall be repaid…
  • Of the total, €55 million was spent on

Obviously, if a text that does otherwise is cited, the original choices should be copied.

4)         Principles 1 to 3 also apply to ordinal numbers (e.g. second, fourth, 12th, 51st)[1].

The cut-off line for expressing numbers as figures or in words might deviate somewhat[2].

Ordinals (cardinal numbers) should not be abbreviated as a figure extended by stndrd or th. If you nevertheless abbreviate them, never spell as 2d or 3d (or their larger ordinals ending in -2d or -3d)[3].

Note that the adverbs firstlysecondlythirdly and fourthly have a stronger signalling effect than their equally valid counterparts firstsecondthird and fourth. However, none of them should be used where the enumeration continues beyond to (sic) fifthly and so forth.

5)         Use commas to separate grouped thousands and use points to separate round numbers from decimals (or vice versa).

The opposite usage, of points to separate thousands and commas for decimals, is found in relatively few English-speaking countries (and must therefore be discouraged). Note however, that this may well be different in many other languages, which is why the opposite use would be appropriate as well. Avoid the use of hard spaces and quotes (e.g. not 16 000 000 or 5’200’554). Nevertheless quotes are common in several European countries (e.g. Switzerland).

For example:

  • EUR 2,750.75 plus EUR 1,249.25 equals EUR 4,000.

Do not group serial and page numbers in thousands (e.g. page 1263 not page 1,263).

In tables write:

  • EUR ’000 or EUR thousand, but not: in EUR 1,000
  • Kilotonnes, kT, thousand tonnes or thousands of tonnes, but not: in 1,000 tonnes

When translating a contract or if two language versions are printed alongside each otherdo not replace commas with points in the translation.

Telephone and fax numbers and postal codes are not grouped by thousands, but are grouped in accordance with the national practice applied in the country of that particular number. Do not apply the national writing practices of one country to phone numbers of other countries.

In particular in international contracts, include the international dial-in code as a prefix, preceded by a plus (+) and place the initial zero between brackets if it should not be dialled after the international dial-in code. For example:

  • +1 510 642 1799                 for a U.S. number
  • +31 (0)20 616 9696            for a Dutch number
  • +39 06 696 211                   for an Italian (fixed line) number

Postal codes are not grouped by thousands but in accordance with the national practice applied in the country of that particular number. Also, they must be placed before or after the town name as local practices determine.

6)         Write out hundred and thousand in words or figures as is required for consistency. For rounded millions or higher use figures, words or their combination.

For example:

  • 500 or five hundred but not 5 hundred
  • EUR 3,000 or three thousand euro but not EUR 3 thousand
  • 2.5 million, 3 million, 31 billion

When writing out (very) large numbers, do not use and, except for separating the decimals. For example: EUR 150,697,345.45 (one hundred fifty million six hundred ninety-seven thousand three hundred forty-five euro and 45 cent).

7)         Avoid abbreviating millions by M or mln.

In several languages, the abbreviation M or m is used for thousands (e.g. in French, Italian and Spanish thousand is ‘mille’ or ‘mil’). Note that in Roman numbering, M indicates one thousand. Do not abbreviate billions (or more).

When used, the abbreviation may either be preceded by a hard space[4] or be closed up where the preceding figure does not contain a space.

For example:

  • Neither EUR 375,000 m nor GBP 864,000 bn
  • Neither € 375m nor £ 864bn

8)         Avoid combining single-digit figures and words by using hyphens, but write out instead.

For example:

  • a three-year term; a five-door car

But note custom phrases such as:

  • 40-hour week, 24-hour services, 4-wheel drive

9)         Do not add two decimal zeros after round (cardinal) amounts. For figures smaller than 1 add zero before the point.

An exception may apply when consistency so requires, for example in tables or when other amounts are not round amounts (and all are part of one calculation). Do not cut off decimals if all cut-off decimals are zeros: the zeros increase precision. For example:

  • EUR 2,750.75 plus EUR 6,000.00 plus EUR 1,249.25 equals EUR 10,000.
  • …such excess EBITDA shall be multiplied by 8.3…
  • …the default interest shall be further increased by 0.85…

Do not write out decimals.

10)       When two numbers are adjacent, spell out one of them.

Usually, it would be the first. For example:

  • 140 fifty-kilogram packages
  • Seventy 44-eurocent stamps

11)       Compound numbers that are written out, take a hyphen.

Numbers below one hundred are compounded. For example:

  • thirty-first
  • nineteen hundred sixty-six

12)       Use figures in a combination with units of measurement that are denoted by a symbol or an abbreviation.

For example:

  • 250 kW or two hundred and fifty kilowatts
  • 205 μg or two hundred and five micrograms
  • 5 °C or five degrees Celsius

The opposite does not hold. If the units of measurement are spelled out, the numbers may be written as figures:

  • 250 kilowatts, 500 metres.

13)       In contract clauses, use the official (ISO) currency abbreviation with the related amounts (that appear in figures).

Examples of the official ISO currency abbreviations are EUR, USD and GBP.[5] Note that the official notation of U.S. Dollars is USD and not US$, even though various style guides recommend its use in combination with figures (note that U.S. is otherwise abbreviated with points).

Accordingly, do not use the currency symbol (e.g. €, $, £). This principle also applies to the use of figures in tables, formulae and texts which consist largely of figures. Similarly use EUR rather than the  sign (but if you do use €, a hard space should be inserted before the figure). For example:

  • EUR 50 or one hundred euro

If, despite the above best practice rule, you do use the currency symbol, never put it behind the amount unless the national rule so prescribes for that symbol (i.e. never write 50€, 134$ or 13£).

The official plural of euro is euro (i.e. not euros). The official rule is not to capitalise euro (i.e. not Euro).

14)       Reserve the word amount for valuations and prices only. When applicable, the contract drafter determines unit measurements.

For example, refer to numbers of persons or companies but not amounts of persons or companies.

With figures, use a person or per person, a year or per year, not per caput, per capita or per annum. Also use percent or per cent instead of the % sign. Write percentage, never write %age (consider also using proportion or share).

In most non-American contexts, use hectares instead of acres, kilometres (or km) instead of miles, metres instead of yards, litres instead of gallons, kilos instead of lb, tonnes instead of tonsCelsius instead of Fahrenheit. Exceptions apply for those units of measurement that are determined by international market standards; for example, oil is measured by barrels and gallons (there are 3.78541 liters in a gallon and 42 U.S. gallons in a barrel).

In a U.S. context, more familiar measurements can be used as well. Be aware, however, that American pints, quarts and gallons are smaller than their British counterparts.

15) Avoid using fractions.

When fractions are used as adverbs or adjectives, insert hyphens. Do not insert hyphens if the fraction is a noun. In a closely linked phrase avoid combining fractions and words.

For example:

a two-thirds increase
increased by two thirds
two-thirds completed, but not: ⅔ completed

Never contrast or compare a fraction with a decimal (i.e. avoid the applicable interest rate shall be 6¼ percent instead of 5.1 percent).

16) When used, fractions should always be spelled out in words, even when the figures are higher than ten, unless they relate to round numbers.

For example:

The JVC shall budget one tenth to developing its distribution network, a twentieth to R&D and no more than a thirtieth to raw materials.

Fractions are subject to the general drafting principle of ‘be accurate’; in many cases, fractions are more precise than decimals (e.g. 6.33 neglects the implied infinity of the fraction, which is embraced by 6⅓). Alternatively use fractions for rough figures, e.g. the JVC shall make best efforts to decrease production costs by 3½ percent a year, and decimals for more exact figures, e.g. the retail price index is rising at an annual rate of 10.6 percent.

Note that 2.5 (as in 2.5 percent) is not the same as 2.50 or ! Each decimal place, even if zero, adds to the accuracy. The non-decimal fraction is more approximate.

17) Do not use a hyphen except with figures.

Example (of incorrect use):

The initial lease term is 15-20 years, each time extendable by 5-10 years.
He promised to extend the initial term within three to four weeks from the signing date.

For indicating ranges, use a hyphen ( – ) not an em-dash ( – ) (a wide type of dash). Note that dashes are used to emphasise a phrase – or word – as opposed to commas or parentheses (which explain or add something without necessarily giving it emphasis).

18) When a range is indicated by a dash, do not repeat the symbol or multiple if they do not change. Close up the dash between the figures.

For example:

5,000-6,000, 5-6 percent, 5m-6m (not 5-6m) and 5 billion-6 billion.

In running text, use to. For example, provided that sales increase from 5m to 6m and estimates range between 5m and 6m. So do not write 5m-6m in either case.

If the symbol or multiple changes, however, leave a blank space on either side of the dash and preferably use an em-dash. For example:

100 kW – 40 MW

Where to would be part of a ratio, spell it out. For example, The General Meeting decided, by nine votes to two, to put the matter to the general assembly which voted 27 to 19. Where a ratio is used as an adjective, figures and hyphens may be used, but only if one of the figures is greater than ten: thus a 50-20 vote, a 19-9 vote. Otherwise, set the figures in words and use to (as well as hyphens because it is a ‘grouped adjective’). For example: a five-to-two vote, a ten-to-one probability.

[1] EC DG Translation, English Style Guide – A handbook for authors and translators in the European Commission, revised edition 2009; and:
[2]      The Word shortcut-key (toggle on/off) for superscript is Ctrl-Shift =.
[3]      Bryan Garner, The Redbook, a manual on legal style, 2nd edition, Thomson 2006, § 5.2(b) proposes a cut-off at twelfth.
[4]      An exception applies to U.S. case law citations (where this abbreviation rule is reversed).
[5]      To insert a hard space press Ctrl-Shift Space.
[6]      The standard official abbreviations are listed in ISO 4217.