Furnaces tend to fail on the coldest night of the year, which is exactly when you have the least leverage to compare quotes. Knowing the real numbers ahead of time fixes that.
This guide covers what a furnace actually costs installed in 2026, what AFUE means for your gas bill, how to size one properly, and an honest note on where furnace replacement fits into rebate programs.
By Sam Menard · Updated September 2026 · 9 min read
Most homeowners pay between $2,800 and $7,500 for a fully installed gas furnace in 2026, with a national average around $4,500. The spread comes down to AFUE rating, home size, and whether venting or ductwork needs work.
Labor typically runs $500-$2,000 on top of equipment cost, with installers charging $50-$100/hour. Equipment alone tends to price out around $1,000-$1,500 per ton of heating capacity — the installed total above already includes that.
What AFUE Actually Means
AFUE (Annual Fuel Utilization Efficiency) tells you what share of the gas you burn actually becomes heat in your house, versus what goes out the flue. An 80% AFUE furnace turns 80 cents of every gas dollar into heat; a 96% AFUE furnace turns 96 cents.
80-89% AFUE: lower upfront cost, standard venting. A reasonable choice in a mild climate with a short heating season.
96%+ AFUE: costs $1,000-$2,500 more upfront and needs different venting (PVC instead of metal flue), but burns noticeably less gas. In a cold climate with a long heating season, this usually pays for itself over the furnace's life.
Sizing It Right
Furnace size is measured in BTUs of heat output, not tons. As with AC, square footage alone is a rough starting point, not a real answer.
What changes the number: insulation quality, window count, ceiling height, air leakage, and your region's design temperature (the coldest realistic outdoor temperature your furnace needs to handle).
The real answer: a Manual J heat loss calculation from your installer. Oversized furnaces short-cycle — turning on and off repeatedly — which wears out components faster and leaves rooms unevenly heated.
What to Ask an Installer
"Can I see the Manual J heat loss calculation, not just a square-footage estimate?"
"What's the AFUE rating, and what's the price difference to go to 96%+?"
"Does this furnace need new venting, and is that included in the quote?"
"Is the blower variable-speed or single-stage?" (Variable-speed runs quieter and more efficiently at partial load.)
"What's the full installed price, including any electrical, gas line, or venting work?"
Get at least two quotes for the same AFUE tier and BTU output before you sign — furnace pricing varies more by contractor than by brand for equivalent equipment.
An Honest Note on Rebates
A gas-for-gas furnace replacement doesn't typically qualify for the rebate programs listed on this site. Those rebates are built around heat pumps, which replace both your furnace and central air conditioner with a single electric system that heats in winter and cools in summer.
If your furnace is failing, it's worth getting a heat pump quote alongside your furnace quotes before you decide. Rebate eligibility can shift the real cost comparison more than people expect.
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