Base 64 converter

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Base64 is a method of encoding information using 64 characters. It allows binary data to be represented in ASCII text, using a set of 64 printable characters. This method is commonly used to transmit data over channels that cannot handle binary data, such as emails and web pages.

The digits of Base64

The digits of Base64 consist of 4 groups:
• Uppercase letters ABCDEFGHIJKLMNOPQRSTUVWXYZ (values 0 to 25)
• Lowercase letters abcdefghijklmnopqrstuvwxyz (values 26 to 51)
• Digits 0123456789 (values 52 to 61)
• Special symbols +/ (values 62 and 63):

The conversion table of Base64 digits to decimal and binary is as follows:

Uppercase letters ABCDEFGHIJKLMNOPQRSTUVWXYZ

A	B	C	D	E	F	G	H	I	J	K	L	M
0	1	2	3	4	5	6	7	8	9	10	11	12
000000	000001	000010	000011	000100	000101	000110	000111	001000	001001	001010	001011	001100

N	O	P	Q	R	S	T	U	V	W	X	Y	Z
13	14	15	16	17	18	19	20	21	22	23	24	25
001101	001110	001111	010000	010001	010010	010011	010100	010101	010110	010111	011000	011001

Lowercase letters abcdefghijklmnopqrstuvwxyz

a	b	c	d	e	f	g	h	i	j	k	l	m
26	27	28	29	30	31	32	33	34	35	36	37	38
011010	011011	011100	011101	011110	011111	100000	100001	100010	100011	100100	100101	100110

n	o	p	q	r	s	t	u	v	w	x	y	z
39	40	41	42	43	44	45	46	47	48	49	50	51
100111	101000	101001	101010	101011	101100	101101	101110	101111	110000	110001	110010	110011

Digits 0123456789

0	1	2	3	4	5	6	7	8	9
52	53	54	55	56	57	58	59	60	61
110100	110101	110110	110111	111000	111001	111010	111011	111100	111101

Symbols + and /

+	/
62	63
111110	111111

In addition to this alphabet, the symbol = is used as a padding character.

Example of encoding a text in Base64

Let's encode the word "Film" in Base64 step by step.

Step 1

Convert the word "Film" to its ASCII binary representation:

	F	i	l	m
Decimal values	70	105	108	109
Binary values	01000110	01101001	01101100	01101101

Step 2

Join the binary values:

01000110 01101001 01101100 01101101

• Group the ASCII binary representation into blocks of 6 bits:

010001 100110 100101 101100 011011 01

Step 3

Add zeros to the right of the last block to make its length equal to 6 bits:

010001 100110 100101 101100 011011 010000

Step 4

Convert each 6-bit block to decimal:

010001 -> 17
100110 -> 38
100101 -> 37
101100 -> 44
011011 -> 27
010000 -> 16

A base2 to base10 converter is here.

Step 5

Base64 encoding using the Base64 correspondence table above:

17 -> R
38 -> m
37 -> l
44 -> k
27 -> b
16 -> Q

Step 6

Concatenate the encoded values and add the padding character = to make the number of characters a multiple of 4 (here 8 characters)(*):

RmlsbQ==

Thus, "Film" in Base64 is written as "RmlsbQ==".

(*) Base64 encoding is done in packets of 4 x 6 bits because 6 bits can exactly represent 64 different values (2^6 = 64). Thus, each group of 6 bits can be represented by a character from the Base64 table. By grouping the original data into packets of 3 bytes (i.e., 3 x 8 = 24 bits), we get 4 groups of 6 bits, each of which can be represented by a Base64 character. This allows binary data to be converted to a more compact and portable textual representation, while avoiding compatibility issues with systems that may not handle certain ASCII characters.