Gas prices for four of Illinois’ 9 major utilities were up from a year ago, led by Liberty Utilities, which is charging a whopping 95 cents per therm supply rate, according to a CUB review of August gas prices.
Gas utilities file supply prices–called the Purchased Gas Adjustment (PGA)–each month with the Illinois Commerce Commission 
(ICC). Here’s a summary of the gas supply rates charged by Illinois’ major utilities:
- Compared with last month, seven utilities charged lower rates: Ameren Illinois (about 5 percent lower), Consumers Gas (about 81 percent lower), Liberty Utilities (about 7 percent lower), MidAmerican Energy (about 14 percent lower), Mt. Carmel (about 35 percent lower), Peoples Gas (about 6 percent lower) and North Shore Gas (about 4 percent lower). Nicor Gas was unchanged, and Illinois Gas was essentially flat (up about 0.3 percent).
- Compared with August 2025, this month’s prices were higher for four utilities, ranging from about 4 percent higher for Mt. Carmel to about 42 percent higher for Liberty Utilities. Liberty’s 95.13 cents per therm rate was easily the highest supply rate charged among Illinois gas utilities. Thankfully, five utilities charged less than last August, ranging from 15 percent lower for Peoples Gas to about 35 percent lower for Consumers Gas. See detailed August pricing information below.
August Gas Prices
Ameren Illinois – 47.88 cents per therm (UP about 12 percent from August 2025)
Consumers Gas – 35.58 cents per therm (DOWN about 35 percent from August 2025)
Illinois Gas – 41.84 cents per therm (DOWN about 18 percent from August 2025)
Liberty Utilities – 95.13 cents per therm (UP about 42 percent from August 2025)
MidAmerican Energy – 39.18 cents per therm (DOWN about 32 percent from August 2025)
Mt. Carmel – 41.23 cents per therm (UP about 4 percent from August 2025)
Nicor Gas – 36.00 cents per therm (DOWN about 31 percent from August 2025)
North Shore Gas – 40.93 cents per therm (UP about 14 percent from August 2025)
Peoples Gas – 36.72 cents per therm (DOWN about 15 percent from August 2025)
Note: Your utility is determined by where you live, so you cannot switch from one utility to another. State regulators annually review the utilities’ gas-management procedures to evaluate whether the companies did a reasonable job with their gas purchases, given market conditions, to hold down costs for consumers as much as possible. Regulators can order refunds, although that is rare.
A few tips from CUB:
- Keep the lines of communication open with your utility. If you are having trouble affording your gas bills, it is vital that you contact your utility. Ask if you can set up a plan that gives you more time to pay off your bills, and inquire about energy assistance and energy efficiency programs the company offers.
- Ask if your utility offers a discount program for qualifying customers. Ameren, Nicor, North Shore and Peoples Gas do.
- See if you qualify for energy assistance. To apply or learn more about the Low Income Home Energy Assistance Program (LIHEAP), visit this state of Illinois webpage. (Also, check out our Step by step guide to applying for LIHEAP.)
- Practice energy efficiency. For tips and information about helpful energy efficiency programs, visit CUB’s Clean Energy page.
- Beware of alternative supplier rip-offs. If a deal seems too good to be true, there’s a good chance it is. If the utility’s gas price increases, remember that it’s due to market factors that also will increase alternative supplier prices. As volatile as gas utility prices are, your best bet for gas supply is likely with your utility and not with an alternative supplier. Read our tips. (Note: Only consumers in Northern Illinois have gas choice.)
- More helpful resources:
- CUB’s Gas page
- CUB’s chart of historical gas prices. Plus, CUB’s gas-price reports from 2026: January, February, March, April, May, June and July.
- 2025: January, February, March, April, May, June, July, August, September, October, November, and December.
- If you want to consider moving away from gas, visit our electrification page and order CUB’s free Better Heat Guide to learn how to make the transition to more efficient appliances, such as electric heat pumps and induction stove tops.
