The 20-year-old said Emma, 21, who has recently been cast opposite Andrew Garfield in the new Spider-Man film as Gwen Stacy, cheers her up on a bad day.
Swift told British Bliss magazine: 'Emma Stone, is absolutely my most hilarious friend.
'She's the best at cheering me up, making me laugh and being an overall entertaining person to have in my life.'
The Mine singer is also grateful for her friendship with Selena Gomez, 18.
She added: 'It's a great friendship.
'We talked for two hours on the phone last night because we haven't been able to talk for like, two weeks... There was advice given and asked on both of our ends.'