According to Official Guinness Records,
The most consecutive haircuts by a team in 24 hours is 618 and was achieved by 10 stylists from Pump Salon at Rookwood Commons & Pavilion in Cincinnati, Ohio, USA, from 24 to 25 September 2010.
The haircuts given were free with all donations given towards 6 different charities. Measuring tapes were used to ensure the start length of hair met the guideline requirements.
For a complete list of 2010 records, please visit 2010 Guinness Records in United States.