Contact Energy had 447,000 electricity customers at the end of June - 7500 fewer than a month earlier and 30,000 fewer than at the end of June last year.
Gas customer numbers fell by 1000 to 60,000 during the month while LPG customer numbers rose by 500 to 59,500.
The average electricity sales price also rose, from $181 to $192 dollars per megawatt hour.
