Hales was born in Hillingdon and attended both Westbrook Hay School and Chesham High School (now Chesham Grammar School) in Buckinghamshire.

His father Gary broke several local batting records (including 321 not out for Gerrards Cross versus Chalfont St Peter in a limited overs league match) while his grandfather Dennis was a talented tennis player who once forced Rod Laver to five sets at Wimbledon. His mother is Lisa Hales.

County cricket

Hales first came to national attention in 2005 when, as a sixteen-year-old, he hit 55 off a single over (three no-balls, eight sixes, one four) in a Cricket Idol T20 tournament at Lords. Ironically, he had been picked for his fast bowling ability.

Hales first represented Buckinghamshire in Minor Counties cricket during the 2006 season, and played for MCC Young Cricketers in the Second XI Championship of 2007. He then impressed whilst trialling with Nottinghamshire in 2007, scoring 218 in only his second appearance for the county, following it up with a hundred and two 95s. Notts offered him a two-year contract until the end of the 2009 season. He made his List A debut in a rain-affected match against Leicestershire in May 2008 and his first-class debut against Somerset in September 2008. During the 2009 season, after an impressive start, he signed a new two-year contract extension. On 29 August 2009, Alex hit the top score in the Pro40 2009, 150 off 102 balls for Nottinghamshire against Worcestershire at Trent Bridge.

In July 2011, Hales made a century for Nottinghamshire in the county championship, a score that, according to Cricinfo marked him as "beginning to warrant the attention of the England selectors": it was the second century of his first-class career. He went on to make 184.

In May 2015, Hales hit six sixes across two overs on the opening day of the NatWest t20 Blast in his 86 not out against Birmingham.

Hales represented England U19s in the summer of 2008 in a series of youth Test matches and ODIs against a touring New Zealand U19's, enjoying a successful time averaging 50 in the Tests and over 30 in the ODIs, including 3 half centuries. After just one season on the county circuit he was named in an England Performance Programme squad in the 09/10 winter. In the 2011 summer he was selected for the England Lions against Sr