Mexican pesos
to words
Convert any peso amount into the wording that Mexican SAT invoices, banks and notaries require. With M.N. and 00/100 ready to paste.
- ◆ No signup · 100 % in your browser
- ◆ Modes: CFDI · Check · Notarial
- ◆ RAE rules applied automatically
Type an amount above…
Local conversion · nothing sent to a server
Same amount · three formats
$1,234.56 MXNMil doscientos treinta y cuatro pesos 56/100 M.N.
Mil doscientos treinta y cuatro pesos con 56/100
($1,234.56) Mil doscientos treinta y cuatro pesos 56/100 M.N.
Why writing pesos correctly in words matters
In Mexico, a misspelled amount can void a bank check, delay an invoice payment or trigger a SAT audit observation. Each scenario has real cost: lost time, fines and, in extreme cases, the nullification of the document.
Three settings concentrate the risk:
- CFDI 4.0: SAT's Anexo 20 requires the suffix "M.N." when the currency is the Mexican peso. Without it, audits flag the invoice as observed.
- Bank check: Mexico's Ley General de Títulos y Operaciones de Crédito mandates that the amount in words match the numeric figure and end with "00/100" to prevent tampering.
- Notarial deed: Mexican notaries reject instruments whose written figure shows apocope, gender or agreement errors.
This converter automates the exact format for each of the three settings and applies RAE writing rules. What is six simultaneous decisions for a human (case, apocope, gender, agreement, decimal fraction and suffix) is resolved here in one keystroke.
What M.N. means and why CFDIs require it
Most tools skip the most important detail. Here is the no-shortcut explanation.
M.N.
Moneda Nacional
Traditional abbreviation found on Mexican invoices, checks, deeds and contracts for decades. Accounting and notarial practice keeps using it by convention and to differentiate from the US dollar.
…56/100 M.N.
MXN
ISO 4217
The ISO 4217 code SAT registers in CFDI 4.0 Anexo 20 as the official nomenclature. It appears in banking systems and electronic invoicing portals.
…56/100 MXN
⚖ Both are valid. Standard practice uses M.N. on checks and deeds, MXN in SAT electronic systems. Our converter outputs M.N. by default; swap two letters if your system requires MXN.
Why is "00/100" always written at the end?
The "00/100" or "X/100" suffix closes the amount and prevents anyone from adding cents later. It is the same reason the written amount is followed by a horizontal line up to the end of the space: an open gap invites tampering. Whether $1,000.00 or $1,234.56, the "/100" segment always appears. Mexico's Ley General de Títulos y Operaciones de Crédito codifies this for checks, and SAT Anexo 20 assumes it implicitly on CFDIs.
How to use the pesos-to-words converter in 3 steps
- 01
Enter the peso amount
Type the figure in the large field. Accepts point or comma as decimal separator and thousands separators. Example:
1234.56,1,234.56or1.234,56all yield the same result. - 02
Pick a mode
CFDI 4.0 for a SAT invoice (uppercase + M.N.). Check for a bank (sentence case + "con 00/100"). Notarial for deeds (parentheses + uppercase + M.N.).
- 03
Copy with one click
Hit Copy for CFDI and the text lands in your clipboard with M.N. and 00/100. Paste it into your invoicing system, an Excel cell or directly onto a printed check.
Modes: CFDI 4.0, bank check and notarial deed
Each Mexican document type has its own format. The converter renders all three correctly without you having to remember the differences.
CFDI 4.0 mode (SAT invoice)
Generates the amount in uppercase with the M.N. suffix and a cents fraction. This is the format SAT expects in the CFDI 4.0 total field when the currency is the Mexican peso. Reduces the risk of audit observations.
Check mode (Mexican bank)
Sentence case with the conjunction "con" before the fraction. This is the form Mexican banks recognise on the space dedicated to the amount in words. It omits "M.N." because the currency is implicit from the issuing bank.
Notarial mode (public deed)
Numeric figure in parentheses followed by the uppercase amount in words and M.N. The canonical format Mexican notaries use on deeds, real estate contracts and wills. Combines numeric precision with formal solemnity.
8 errors that get your document rejected by SAT or the bank
The most common errors on Mexican invoices and checks. Each has a grammatical or legal justification.
❌veintiuno pesos
✅veintiún pesos
The form "veintiún" uses the apocope before a masculine noun. Mexican banks and SAT flag the long form as a formal error.
Source: RAE Ortografía §10.2
❌cien cincuenta pesos
✅ciento cincuenta pesos
"Cien" is used only for exactly 100. From 101 onward it must be "ciento" followed by the rest.
Source: RAE Ortografía §10.3
❌doscientas pesos
✅doscientos pesos
Hundreds agree in gender with the noun. "Peso" is masculine, so the correct form is "doscientos".
Source: RAE Ortografía §10.4
❌treintaiún pesos
✅treinta y un pesos
From 31 upward, tens and units are written separated by "y". Joining them together is incorrect.
Source: RAE Ortografía §10.2
❌un mil pesos
✅mil pesos
"Mil" never takes the article "un" before it. Only "millón" does: "un millón de pesos".
Source: RAE Ortografía §10.5
❌uno millón pesos
✅un millón de pesos
"Uno" must apocopate to "un", and "millón" requires the preposition "de" when followed by a noun.
Source: RAE Ortografía §10.5
❌...PESOS 50/100
✅...PESOS 50/100 M.N.
SAT requires the suffix "M.N." on CFDI 4.0 invoices issued in pesos. Its absence triggers audit observations.
Source: SAT Anexo 20 CFDI 4.0
❌...PESOS
✅...PESOS 00/100 M.N.
"00/100" closes the amount and prevents anyone from adding cents afterward. Without it a check can be voided.
Source: Ley Gral. Títulos y Op. Crédito
RAE rules for writing pesos in words
The converter applies these six rules automatically. Knowing them helps you proofread any document manually.
01 Apocope before masculine noun →
The forms "uno" and "veintiuno" shorten to "un" and "veintiún" when followed by a masculine noun. The same applies to "treinta y uno", "cuarenta y uno", etc.
RAE Ortografía 2010, §10.2
02 Gender agreement in hundreds →
Hundreds (doscientos, trescientos…) agree in gender with the noun they modify. "Peso" is masculine, so it is always "doscientos pesos", never "doscientas pesos".
RAE Ortografía 2010, §10.4
03 Cien vs ciento →
"Cien" is used only when the number is exactly 100 or multiplies ("cien mil", "cien millones"). From 101 to 199 it must be "ciento" followed by the rest.
RAE Ortografía 2010, §10.3
04 Conjunction "y" between tens and units →
"Y" is written only between tens and units starting at 31: "treinta y uno", "noventa y ocho". Never between hundreds and the rest — "ciento cinco" is right, "ciento y cinco" is wrong.
RAE Ortografía 2010, §10.2
05 Mil never takes an article →
"Mil" is never preceded by "un". The form "un mil pesos" is always incorrect. "Millón", on the other hand, does take "un": "un millón de pesos".
RAE Ortografía 2010, §10.5
06 Million with preposition "de" →
After "millón", "billón" and higher, the preposition "de" appears when followed by a noun. However, if the million is followed by more digits, the "de" drops.
RAE Ortografía 2010, §10.5
Bonus · 07 Convert words to a number →
Frequently asked questions
01 Is the Mexican pesos to words converter really free? +
02 Do I need to create an account? +
03 What is the difference between "M.N." and "MXN" on a CFDI invoice? +
04 Why do checks require "00/100" even when the amount is exact? +
05 What is the difference between "veintiún pesos" and "veintiuno pesos"? +
06 Why is it "doscientos pesos" and not "doscientas pesos"? +
07 Does SAT reject an invoice if the amount in words is misspelled? +
08 Does it work for amounts above one million pesos? +
09 Can I use it in Excel or Google Sheets? +
10 Which format do I use for a notarial deed vs a check? +
Converters for other currencies
Editorial team · contador-de-palabras.com
Text tools for Spanish-speaking professionals since 2024. Every rule is verified against official sources before publishing.