• in mathematics, an injective function (one-to-one) or a bijective function (one-to-one correspondence)
• in telecommunications, one-to-one (communication)
• in computer science, one to one computing

One to One can also refer to:

• One to One, a 1980s Canadian pop music group
• One to One, an album by Howard Jones
• One to One, Apple's personal training service at Apple Retail Stores
• One 2 One, a British mobile telecommunications company, now part of T-Mobile

See also

• One-to-many
• Many-to-many