Customer Reference
Nearly every ATM keypad has letters as well as numbers — a 3×4 grid pairing digits with letter groups. What looks like a random arrangement on an ATM keypad with letters is in fact a decades-old international standard.
About the layout
The letters on an ATM keypad follow ITU E.161, an international standard originally designed for telephone dialling. Each digit is assigned a fixed group of letters: 2 carries A, B and C; 3 carries D, E and F — continuing in sequence to 9, which holds W, X, Y and Z.
Keys 1, 0, * and # carry no letters. This is a convention carried over from early telephony, where those positions were reserved for operator and signalling functions rather than alphabetic input.
Background
From the first cash dispenser in 1967 to the 3 million machines operating today.
Barclays Bank in Enfield, London installs the world's first cash dispenser, designed by John Shepherd-Barron. It used paper cheques treated with carbon-14 rather than a numeric code — security through chemistry. You can read more about this on the Wikipedia ATM History archive.
Lloyds Bank introduces the first PIN-based cash machine. The 4-digit format was chosen partly because inventor James Goodfellow's wife could only reliably recall four digits. This design milestone is documented via BBC News coverage celebrating the invention of the personal identification number.
The PLUS network connects cash machines internationally, requiring the numeric keypad to become a truly universal standard — the same 3×4 grid appearing on machines from Tokyo to Toronto.
Predictive text input on mobile phones — using the same key-to-letter mapping found on cash machine keypads — becomes widespread on Nokia handsets. The letter assignments, long overlooked, suddenly carry everyday relevance.
Smartphone touchscreens begin replacing physical keypads in consumer devices. Cash machines worldwide retain the physical 3×4 grid — its tactile reliability and accessibility making it the preferred standard for financial transactions.
Over 3 million cash machines operate globally, every one featuring the same layout. The arrangement of numbers and letters — seemingly arbitrary — follows a standard that has outlasted countless other input technologies.
How it works
Numeric keypads can represent any letter in the alphabet. Each key press corresponds to a letter group. Entering a sequence of digits produces a word when the digits are cross-referenced against the standard mapping.
Each digit key is assigned a fixed group of letters. The assignment follows the same sequence on every compliant device.
To spell a word, press the key that contains the first letter of each character in sequence — one key press per letter.
Predictive systems cross-reference the digit sequence against a dictionary to determine the most likely intended word.
On cash machines, this allows word-based PIN codes to be entered using only the numeric keypad, without additional hardware.
Example sequences
| Digit sequence | Key mapping | Word |
|---|---|---|
| 4663 | GHI · MNO · MNO · DEF | HOME |
| 2665 | ABC · MNO · MNO · JKL | BOOK |
| 7225 | PQRS · ABC · ABC · JKL | PACK |
| 3368 | DEF · DEF · MNO · TUV | FEET |
| 9673 | WXYZ · MNO · PQRS · DEF | WORD |
| 5683 | JKL · MNO · TUV · DEF | LOVE |
Common questions
The letters on an ATM keypad with letters originate from the international telephone standard managed by the International Telecommunication Union (ITU), where each digit maps to a specific group of characters. This allows numeric codes to be remembered as words — for example, 5683 maps to LOVE.
What looks random on an ATM keypad with letters is in fact governed by the ITU E.161 structural directive: 2=ABC, 3=DEF, continuing through to 9=WXYZ. The 1, 0, *, and # keys carry no letters, a convention carried over from early telephony.
Yes. Because the key-to-letter mapping is standardised, any four-letter word can be entered as a numeric PIN on any cash machine worldwide. Many customers find word-based codes easier to recall than arbitrary digit sequences.
Calculators place 7–8–9 at the top row; telephone and cash machine keypads place 1–2–3 at the top. The telephone layout was established by AT&T in 1963 for dialling efficiency. When cash machines adopted telephony-style keypads, they inherited this orientation.