For Latin-based alphabets, normally one.
- The English alphabet and some special characters (period, comma, newline etc.) fits into 7 bits
- Most European alphabets (French, Swedish etc.) plus some more special characters (inverted quotes, copyright/euro/pound/yen symbols etc.) fit into 8 bits
- Non-Latin languages like Russian, Hebrew, Chinese etc. may need two, three or four bytes (16-32 bits) per character or symbol.
To some extent the number of bits per character depends on the character encoding, the numbers above are based on US-ASCII (USA), ISO-8859-1 (Western Europe) and UTF-8 (global), arguably the most common encodings.
