Kelly Clarkson is reportedly convinced she'll be married by the end of the year.

The American singer has been dating talent manager Brandon Blackstock since late last year. They have grown incredibly close and the 30-year-old star is apparently convinced he is The One.

Kelly has been sporting a slimmer frame of late having dropped 30lbs. and it's been claimed her wedding plans are part of the reason she has toned up.

"Kelly's expecting an engagement ring by late summer and to be wed by year's end," a source told National Enquirer.

"Sure she wants to look great for the singing show Duets [she's appearing on], but the driving force behind her weight loss is the holiday nuptials."

Kelly is adamant she wants to look her best when she walks down the aisle. She also likes to make an effort for Brandon and has started to realise the importance of being healthy.

"Kelly has been eating [well] and exercising like crazy because she wants to look good for Brandon," the insider said. "She loves to tell him that when he pops the question she'll be at her ideal weight of 120lbs. and ready to shop for wedding dresses."