Kesha uses a colour wheel to choose her hair dye.

The 27-year-old singer posted an image of the pocket colour wheel to her Instagram this week along with the caption ''hair dye party what color will it be tomorrow ?????'' before stepping out with newly dyed blue hair.

The Instagram image did give fans a hint as to her choice as splatters of blue dye could be seen on the wheel.

Kesha debuted her new pastel blue hair colour as she boarded a place at LAX Airport in Los Angeles wearing a pretty floral dress and yellow bandana.

She most recently dyed her hair pink and green following a rehab stint in January.

The 'Tik Tok' singer spent two months in a rehabilitation center being treated for an eating disorder and says she cried incessantly after her mother dropped her off and worried what people would think of her.

The star recalled to Britain's ELLE magazine: ''The first day at the treatment centre was the scariest of my life. As I lay in the tiny, bare room, crying and clutching a stuffed lion that Mom had given me, I worried what people would think... Sure, I've written songs about partying, but my dirty little secret is that I'm actually incredibly responsible.''