Think you pay too much for electricity? You may be.

An Oct. 1 change in the way electricity is billed means some Chicago households could save money by switching from Integrys Energy Services back to ComEd.

All utility customers can expect their rates to go up, thanks to several factors — from increased energy market competition to last year’s polar vortex, which drove consumption up.

But figuring if you would save is tough, due to the complexity of the new billing structure, said Jim Chilsen, spokesman for the Citizens’ Utility Board. To help with that decision, the CUB developed an online calculator, which can be accessed at: http://www.chicagopowercalculator.com. Consumers using a calculator can enter  their flat per-month rate, along with their monthly power use, to see if they would get a better deal switching back.

“Deciding whether to stay with the Chicago power deal or switch back to ComEd depends on each customer’s housing type and average monthly electricity usage,” CUB Executive Director David Kolata said. “That’s why we created the calculator.”

Integrys was chosen with much fanfare as the city’s electricity supplier by Mayor Rahm Emanuel’s administration in 2012. The move came shortly after voters approved a ballot measure allowing the city to shop for electricity in bulk in hopes of cutting utility bills.

ComEd still handles billing and owns the infrastructure used to deliver electricity. But under the deal, Integrys supplies the city’s power — and will continue to do so until at least May, 2015 when its contract expires.

However, since Emanuel chose the company, energy prices have shot up. And the mayor’s office has renegotiated rates with Integrys at least twice, to get a better deal for consumers.

“The city is trying to make the very best out of what has become a very difficult market for Chicago consumers,” Chilsen said. “The market has become more expensive.”