Number to words (Spanish)

Why you write an amount in words

Spelling a number out in words is a legal safeguard on checks, invoices, contracts, promissory notes and receipts. The written amount backs up the figure in digits: if someone turns a 1,000 into 10,000, the words expose the change. That is exactly why banks ask for both forms on a check and, when the two disagree, honor the amount written in words.

This tool spells the amount in Spanish, the way it must appear on documents across Latin America and Spain, and applies the grammar rules so the wording is correct. Everything runs in your browser: no amount is ever sent to a server.

How to use it

1. Type the amount, with decimals if needed (for example, 1234.56).
2. Pick the currency: Dominican, Mexican, Colombian, Argentine or Chilean peso, Peruvian sol, euro or US dollar. The name switches between singular and plural on its own.
3. Choose UPPERCASE or lowercase. Checks usually require uppercase.
4. Decide whether to include the currency name (check format) or output the number only for other text.

The result is ready to copy with one click, alongside the figure in digits and the cents in xx/100 format.

The Spanish rules it applies

Spanish spells numbers differently from English, and this is where most manual attempts go wrong:

• Sixteen through twenty-nine are single words — dieciséis, veintitrés, veintinueve — while from thirty-one on they split with “y”: treinta y uno, cuarenta y cinco.
• The word “y” only sits between tens and units, never between hundreds and tens. So 132 is “ciento treinta y dos”, but 102 is “ciento dos” with no “y”.
• “Cien” versus “ciento”. Spanish uses “cien” for an exact hundred (100) or as a multiplier (cien mil), and “ciento” when a smaller amount follows: 101 is “ciento uno”.
• Apócope before a noun. In front of the currency, “uno” drops its ending: 1 is “un peso”, 21 is “veintiún pesos”. The same happens before mil and millones.
• Millón takes “de”. When the figure ends exactly on a million, Spanish inserts “de”: 1,000,000 is “un millón de pesos”.
• Cents as xx/100. The decimal part is written as a fraction of one hundred: 56 cents become 56/100; with no cents you write 00/100.

Worked example

For a check of 1,234.56 Dominican pesos, the integer 1234 breaks into mil (1000) plus doscientos treinta y cuatro (234), and the 56 cents ride along as 56/100.

Frequently asked questions

How do you write an amount on a check?

Write the full amount in words, in uppercase, followed by the currency name and the cents as a fraction of one hundred, for example “MIL DOSCIENTOS TREINTA Y CUATRO PESOS CON 56/100”. Filling the leftover space with a line keeps anyone from adding text afterward.

Is it “cien” or “ciento”?

Use “cien” for an exact hundred or as a multiplier (cien mil, cien millones). The moment a smaller quantity follows, it becomes “ciento”: ciento uno, ciento cincuenta. You never say “cien uno”.

Where does the “y” go?

Only between the tens and the units: “treinta y cinco”, “noventa y ocho”. It never appears after the hundreds or after “mil”, so 2015 is “dos mil quince”, not “dos mil y quince”.