Vigenere Table (Tabula Recta)

What Is the Vigenere Table?

The Vigenere table, Vigenere square, Vigenere grid, and tabula recta all refer to the same 26x26 grid of shifted alphabets. Some tutorials also call it a Vigenere chart or Vigenere alphabet chart. It is the traditional lookup table for encrypting and decrypting Vigenere messages by hand.

Each row is a Caesar-shifted alphabet:

• row A has no shift
• row B shifts the alphabet by 1
• row C shifts it by 2
• ...
• row Z shifts it by 25

Johannes Trithemius described the tabula recta before the repeating-key method became associated with Vigenere. The table remains useful because it makes the row-column relationship easy to see.

How to Read the Table for Encryption

The most common orientation is:

1. Find the key letter on the left row label.
2. Find the plaintext letter along the top column label.
3. Read the ciphertext letter at the intersection.

Example:

Plaintext letter: H
Key letter:       L
Intersection:     S

So H encrypted with key letter L becomes S.

Some printed tables put plaintext on the left and key letters on top. Because Vigenere encryption adds the two letter values, the encryption result is the same either way. For decryption, however, be consistent with the orientation you are using.

How to Use the Table for Decryption

With the common key-row orientation:

1. Find the key letter row.
2. Scan across that row until you find the ciphertext letter.
3. Move up to the column header.
4. The column header is the plaintext letter.

Example:

Ciphertext letter: S
Key letter:        L
Plaintext column:  H

So S decrypted with key letter L becomes H.

Vigenere Table vs Tabula Recta

These terms are often used interchangeably:

Term	Meaning
Tabula recta	Latin name for the square table of shifted alphabets
Vigenere table	Practical lookup table for the Vigenere cipher
Vigenere square	Another name for the same 26x26 grid
Vigenere grid	Same 26x26 grid, emphasizing the row-and-column layout
Vigenere chart	Informal name used in many learning resources

If a tutorial says "use the Vigenere square," "read the Vigenere grid," or "look up the Vigenere chart," it is referring to this same table.

The Vigenere wheel is a closely related tool: instead of a flat grid, it builds the same shifted alphabets onto two concentric rotating disks. Turning the inner disk to a key letter exposes the same letter pairings the table shows, so the wheel and the table produce identical results.

Worked Mini Example

Encrypt DOG with the key CAT:

Plain	Key	Lookup	Cipher
D	C	row C, column D	F
O	A	row A, column O	O
G	T	row T, column G	Z

Result: DOG -> FOZ

To decrypt FOZ with CAT, scan row C for F, row A for O, and row T for Z, then read the column headers: DOG.

Why the Table Helps

The table is not required if you know the formula, but it helps learners:

• see that each key letter selects a Caesar alphabet
• avoid arithmetic mistakes during manual encryption
• understand why the same plaintext letter can encrypt differently
• reverse the process visually during decryption

Frequently Asked Questions

Is the Vigenere table the same as the tabula recta?

Yes. "Vigenere table," "Vigenere square," "Vigenere grid," "Vigenere chart," and "tabula recta" normally mean the same 26x26 grid of shifted alphabets. The Vigenere wheel is the same idea rebuilt as two rotating alphabet disks.

Which axis is the key and which axis is the plaintext?

This tool uses the key as the row and the plaintext as the column. Some sources swap them. Encryption gives the same result either way, but decryption instructions must match the chosen orientation.

How do I decrypt with the table?

Find the key row, locate the ciphertext letter inside that row, then trace upward to the column header. The column header is the plaintext letter.

Can the table support other alphabets?

Yes, but the table must be rebuilt for the alphabet size and character set. The standard table uses the 26-letter Latin alphabet A-Z.

Related Tools

• Try encryption on the Vigenere cipher encoder
• Break ciphertext with the Vigenere decoder
• Practice full examples on the Vigenere examples page

Conclusion

The Vigenere table is a compact visual model of the cipher. Once you know which row and column represent the key and plaintext, the same square explains encryption, decryption, and the relationship between Vigenere and Caesar shifts.