Be aware that varchars will in general provide slower updates but faster selects. By definition, the amount of storage they use is variable.
Source: wiktionary
Varchar
/ˈvɑɹt͡ʃɑɹ/
Synonyms for "varchar"
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Sample sentences
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With a varchar, the storage is always the actual number of characters you have stored plus 2 bytes. So a varchar(20) with a 5-character word will take up 7 bytes, with the extra 2 bytes holding a size reference for SQL Server.
Source: wiktionary