Sometimes I read $x USD. E.g.:

$900 USD purchase price

Why not simply write 900 USD, without the $ symbol? In other words, when writing $x USD, does the $ serve any purpose?

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    USD 900 million is the order. In written texts. – Lambie Apr 28 at 20:50
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    You can also write US$900, which is a little unofficial but pretty well understood. – Toby Bartels Apr 29 at 5:13
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    Back in the days of hand written receipts, checks, and IOUs the dollar symbol was commonly used domestically to prevent the prepending of any digits to a monetary value. For example USD 500.00 can easily be changed to USD1500.00 but $500.00 is more difficult to change. – EllieK Apr 29 at 12:50
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    side note: please do NOT write "$900 dollars". It's either "$900" or "900 dollars", never both at once. – Hellion Apr 29 at 14:08
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    @FranckDernoncourt Got it. Sorry. I will upvote. – Kentaro Apr 29 at 21:16

U.S. currency is denominated with "$" prefix, and many Americans would simply find the missing "$" confusing, as it is always written that way in informal contexts.

The "USD" clarifies which "$", e.g. not Canadian, Australian, etc.

Edit: In the world of business and international trade, you could leave out the "$", but consider that ~5% of U.S. citizens never even completed high school, and most likely wouldn't even know what "USD" means. So consider your audience.

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    $ also refers to the Mexican Peso, hence why both $ and USD are necessary to express unambiguously. – tadman Apr 29 at 9:55
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    USD alone is sufficient; there is no other currency with a different symbol referred to as USD. – chepner Apr 29 at 11:45
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    Possibly of note, a number of other currency symbols have the same issue. ¢, £, ¥, ₩, and ₨ all have multiple associated currencies, as do some ‘plain letter’ symbols such as ‘kr’ and ‘F’ – Austin Hemmelgarn Apr 29 at 12:02
  • @AustinHemmelgarn although less likely to be miscommunication as most (all?) of those associated currencies are associated with different languages. I.e. mixing up GBP and EGP is less likely than USD and CAD! – Tim Apr 29 at 21:55
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    +1 for consider your audience. – Ethan Bolker May 2 at 14:02

Strictly, no it doesn't.

The "USD" itself means "United States Dollar", in the same way that "CAD" means "Canadian Dollar" or "AUD" means "Australian Dollar" and in their original places of use, such as Forex trading, wouldn't be written with symbols.

Part of it was that while the character sets we used back then would have had '$' signs, for size, they'd often not even have lower-case chars, let alone symbols other than '.', '%', '$' and '[space]'!

Having said that, as time has moved on, the USD's seen outside the original areas and in more general usage, hence "US$" or "USD $" as that looks more familiar to 'non-professionals', so the answer is really that the purpose of it is to look more familiar to users not familiar with the 'historic' usage of USD.


No, it doesn't, and is a mistake of the same kind as saying "ATM machine" (automatic teller machine machine), or "PIN number" (personal identification number number). It's a combination of sloppiness and not knowing that "D" in USD stands for "dollar". It's been made significantly worse through the sloppy coding practices on many websites, where the developers either couldn't or didn't care to get the code responsible for displaying prices right, which is also why it's skyrocketed in prevalence in recent years. Nowadays, it's not even particularly hard to find even sloppier "USD dollars", and I've actually seen an instance of "$X USD dollars".

The correct way to refer to a price in US Dollars is one of the following:

  • $X (implicit currency)
  • $X US (explicit)
  • X USD (explicit)
  • US$ X (explicit)

Analogous versions exist for all other currencies called "dollar", and for other currencies in general.

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    Saying PIN number is perhaps redundant, but not incorrect. A PIN is a number, so it's perfectly logically correct. And there's no (significant) issue I see with grammaticality either—PIN is being used as an adjective, pure and simple. It even has some value, as PIN number will convey the information more reliably than PIN alone, in spoken English. – lukeuser Apr 30 at 7:51
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    It is no more correct than saying "personal identification number number" is. It's "a PIN", and using it as an adjective is erroneous, because of what PIN means. Is it common? Sure, it is. So are many other incorrect constructs stemming from ignorance of what things mean. – mathrick Apr 30 at 16:22
  • @lukeuser Regarding language use, sure, there is no "incorrect", only things like "uncommon", "redundant", "ambiguous", etc. (and I am aware that such a combination of "like" and "etc." is also an example of redundancy that I'd usually try to avoid). In the OP context, one may perhaps have to look beyond mere linguistic correctness and consider some formal aspects of the usage -- such as: Could you sue me if you sell me something for $900 and later find out that the envelope I gave you contained Mexican pesos instead of US dollars (dunno why you didn't check, but for the sake of example...)? – Hagen von Eitzen May 1 at 7:23
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    @mathrick It has nothing to do with ignorance. I just explained (one reason) why people say PIN number and it is not because they don't know what PIN means. You say using PIN as an adjective is erroneous "because of what it means", but one can only use a word as an adjective if one already knows what the original noun means, so that is a strange argument. Of course, number can also be used as an adjective by itself, such as "number theory", so your argument is faulty on multiple levels. – lukeuser May 1 at 15:51
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    @mathrick There are many reasons to say PIN number rather than PIN (using PIN as an adjective rather than a noun). Apart from the one I've mentioned, it also makes it explicit that the thing in question is a number. But there's no reason to use "personal identification number number" over "personal identification number", and good reason not to (the repeated number is inherently confusing). So noöne does that. Generally speaking, noun phrases don't suit being used as adjectives; the result is difficult to correctly parse—but this issue disappears when one uses the acronym instead. – lukeuser May 1 at 16:34

I find it clearer to read, and worry that some readers might not know what "USD" means there, or not notice that it is a price because they are used to seeing the dollar sign. So I choose to write both the $ and the USD. The $ makes it stand out and register as a price easily, and is understood by all. The extra USD then clarifies that I mean U.S. dollars, and the context of it being after what is already understood as a price makes it meaningful even to people who don't immediately know the abbreviations. I suppose putting the latter in parens would be more correct and still work the same: " $100 (USD) " On a web page, the "USD" should have an abbreviation tag that spells it out.


$x USD is redundant and thus kind of annoying, but not wrong wrong like "knots per hour" or "rate of speed", and partially justified for the sake of clarity (as many redundancies are) since as others have said, there are many $'s, some of them not even "dollars". If you're reading it, sigh and move on.

If you're writing it, try to avoid it. US$/CA$/AU$ (or C$/A$ if that's going to be clear) is a fine alternative for cases where your audience will want to see the dollar sign. USD/CAD/AUD is the way to go for technical documents or backend databases. For catalog pages, a good solution is to use $ in the price field and somewhere else on the page put an indication of currency and locale, like "USD" and the flag, since you're also indicating a willingness to ship to that place.

You could also just put USD in parentheses and tell the nitpickers it's not redundant, it's a subordinate phrase to remove ambiguity.

In news articles, I frequently find things like "Acme stock is up xx% from a low of $yyyyyy after splitting at $zzzzzz following their $10M purchase of Zenith, Inc (all figures in US Dollars)."

Far more annoying is "$100 million dollars". Are we to take that as a hundred million dollar dollars? One hundred dollars million dollars"? Or just assume that whoever's writing something, may not actually know how to read?

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    Yes, it should be: $100 million, without the word dollars. Or it has be written out in full: one hundred million dollars. – Lambie Apr 30 at 20:09
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    "Knots per hour" is not wrong if used to refer to acceleration... but it usually isn't. – randomhead May 1 at 19:43

At first it looks like this is the practice? only seen in the U.S, but since Rich commented there are a few countries using dollars, so I googled by "$100AUD" and "&100NZD".


From this site,,

enter image description here

It says $100AUD.

New Zealand

enter image description here

From this site,

The banknote is called "$100 NZD"

The U.S

From this site,

enter image description here

So when there are countries calling their currency **** dollars, in order to distinguish from the others they use $***Country Code?

In all countries the symbol $ represents or called "dollar", the symbol virtually serves as the "money" and the details (which country it is) is added after the amount, I guess?

Single(No other countries use the name) currency ex, Japan and EU,

In our country, how many times I googled like,

¥(YEN)10,000YEN nothing comes up.

(I googled by "€100 euro" nothing came up.)

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    There is only one EUR (or JPY, I think). There are many countries with a currency called a dollar. – Rich Apr 30 at 1:23
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    Those sites are ALL wrong. – Lambie Apr 30 at 20:07
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    I mean the signs come FIRST: US$100, that is the pattern. Nothing else, with the sign $. Or: $100 – Lambie Apr 30 at 20:37
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    Kentarosan, I will not "ask the twitter" anything. :) – Lambie Apr 30 at 20:46
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    Yes, Kentarosan. I most heartily disagree with them. – Lambie Apr 30 at 20:59

It helps for international audience.
"Anybody" in the world will recognize a number near a $ sign as a price. This is not true for USD.
USD is more for english (or educated) audience that knows there could be dollars in other countries too and that could make a difference.

$1 fine
$1 USD is redundant except for countries that use $ but not USD
$1 CAD fine

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