AFUE Ratings Guide

If you’re realizing that it’s time to upgrade your furnace, one of the first steps is to settle on an efficiency rating. That rating selection will impact your up-front costs and what you pay for home heating in the future. With this handy guide, you’ll understand more about AFUE ratings and how they affect you.

What Is an AFUE Rating?

AFUE is an acronym for Annual Fuel Utilization Efficiency. It is an industry-standard measurement for how efficiently a furnace or boiler converts fuel into heat for your home within a year. The higher the AFUE rating (on a scale of 0% to 100%), the more efficient the system is at converting fuel into usable heat.

How Is AFUE Measured?

AFUE ratings are determined by calculating the ratio of a furnace’s heat output to the fuel it requires in the process. This calculation factors in the energy lost through exhaust gases, radiation and other factors that diminish efficiency. The result is displayed as a percentage, representing the amount of fuel converted into heat.

Calculating a furnace’s AFUE rating includes conducting a standard test cycle to quantify the heat output and fuel consumption. This test cycle is designed to simulate typical heating conditions throughout the year, including both in-season and out-of-season periods. The heating system operates at peak capacity for an extended period to define its peak performance.

What Is the Minimum AFUE Rating in 2023?

The U.S. Department of Energy (DOE) has steadily increased HVAC efficiency ratings over the past few decades in an effort to encourage energy efficiency and reduce greenhouse gas emissions. In 2023, the minimum rating for new gas furnaces was recalculated to be 81 AFUE. From 2015 to 2022, the South and Southwest regions had a minimum rating of 80 AFUE, and the North called for furnaces to be rated 90 AFUE or higher. Better AFUE ratings cut down energy consumption, lowers utility bills and decreases the environmental consequence of heating your home.

Why Do Gas Furnaces Jump from 80 to 90 AFUE?

When shopping for new furnaces, you may discover many models around 80 and 90 AFUE, with little in between. This is mainly because the technology needed to exceed 80 AFUE forces a substantial jump in performance.

The 80 AFUE threshold has been the minimum expectation for gas furnaces in the USA since the 1990s. At this level, furnaces turn 80% of the fuel they consume into heat, with the remaining 20% lost to the atmosphere through the flue.

Gas furnaces must incorporate more innovative technology to secure higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and supplementary heat exchangers. These features help the furnace pull heat from the fuel source more effectively, boosting efficiency from 80 to 90 AFUE or higher. Today’s best furnaces cap out at approximately 98.5 AFUE.

How Do AFUE Ratings Influence Furnace Costs?

The cost of a furnace with a higher AFUE rating is normally higher than that of a lower AFUE-rated furnace. Basically, more sophisticated technologies come at a cost. The exact cost difference will depend on the furnace manufacturer, size and efficiency rating.

When thinking about the purchase price of a more efficient furnace, don’t forget the future energy savings that awaits you. The potential to save money on energy bills for the next decade or longer helps you to recoup the extra up-front investment.

Should You Buy a Furnace with the Highest AFUE Rating Possible?

While a higher AFUE rating translates into more efficient home heating and lower energy bills, we are not recommending that everyone should choose a 95 AFUE furnace. Below are a few factors to consider when evaluating costs and efficiency ratings:

  • Local weather: The colder the climate, the longer your high-efficiency furnace runs, and the faster you will realize an overall savings from your investment. For that reason, higher AFUE ratings are most appropriate in cold climates that take more heating than cooling to maintain a comfy indoor temperature.
  • How long you’ll live in this home: If you imagine living in your home for quite a while, choosing a high-efficiency furnace may be a good investment because it will pay for itself over the next few years in energy savings. But, if you’re going to move within the next few years, the extra cost of a higher AFUE-rated furnace would not be recommended.
  • The cost of fuel: The affect of an efficient furnace is more pronounced when energy costs are higher. You’ll experience noticeable savings once your furnace converts a higher percentage of fuel into usable heat for your home.

Consider a New Furnace Today

For help determining the best heating system for your needs and budget, select Service Experts Heating, Air Conditioning & Plumbing. We can help you weigh the initial costs and long-term benefits of different AFUE ratings to inform your decision. We’re so confident you’ll be satisfied with our services that we offer a 100% satisfaction guarantee! To find out more or to schedule a complimentary furnace installation estimate, please call a Service Experts office near you.

Savings For You

See All Offers Here >


  • Upgrade to Worry-Free Comfort with the Advantage Program and make NO payments for 30 days!


  • Save $50 on a Paid Service
  • Written 100% Satisfaction Guarantee
  • Plus, ask how to save an additional 15% and waive your trip charge!

© 2024 Service Experts, Service Experts Heating & Air Conditioning, and the Service Experts logo and design are registered trademarks of Service Experts LLC and used under license by SE Canada Inc. All Rights Reserved. *Not applicable to the Advantage Program. See your signed Advantage Program Agreement for full details and exclusions. 100% Satisfaction Guarantee is subject to certain restrictions and limitations as set forth in the applicable Terms and Conditions.

Chat with a Service Experts Professional