Furnace replacement cost: standard and high-efficiency gas furnaces, by state
A 100,000 BTU furnace: about $3,700 to $4,350, typically $3,950. That's a new gas forced-air furnace with the old one taken out, plus the contractor's overhead, profit and sales tax. New ductwork, venting changes, a new air conditioner and permits are extra.
Anthony Hicks30+ years in construction. Updated November 5, 2026.
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What it costs
| Job | Cost |
|---|---|
| A 60,000 to 75,000 BTU furnace | $3,250 to $3,900 |
| A 100,000 BTU furnace | $3,700 to $4,350 |
| A 100,000 BTU high-efficiency furnace | $4,850 to $5,700 |
Totals include the contractor's overhead and profit (20%) and the state's average sales tax. Prices as of November 2026.
What’s in these numbers
Each total is a typical job, priced the way a contractor’s estimate is priced:
- A new gas forced-air furnace in the size shown, set and connected, with the old furnace taken out.
- Overhead and profit: 20%, the standard markup on a contractor’s estimate.
- Sales tax on the materials, at the state’s average rate.
Not in them: new or changed ductwork, a new flue or vent, a new gas line, the air conditioner and its coil, a thermostat, and permits.
Standard or high-efficiency
A furnace’s AFUE is the share of the fuel’s heat that ends up heating the house instead of going up the vent. The federal floor for a new indoor gas furnace is 80% AFUE today, and 95% for gas furnaces made on or after December 18, 2028 (10 CFR 430.32(e)). ENERGY STAR certifies gas furnaces at 95% AFUE or better in the southern states and 97% or better in the northern ones.
A high-efficiency furnace costs more to buy and install; it burns less gas for the same heat.
What size furnace
The code sizes heating equipment from a load calculation of the house, ACCA Manual J, and picks the equipment by ACCA Manual S (IRC M1401.3). The load depends on the house’s size, insulation, windows and climate, so two houses of the same floor area can need different furnaces. A replacement is the time to check that the old furnace’s size still fits the house.
What moves the price
- Efficiency. High-efficiency furnaces cost more than standard ones of the same size.
- Size. Bigger furnaces cost more.
- Venting and ducts. A change of furnace type or location can mean new venting, and leaky or undersized ducts add work.
- Access. Attics, crawl spaces and tight closets take longer than an open basement.
- Where you live. Pick your state in the box above.
Common questions
How much does a new furnace cost?
About $3,700 to $4,350 for a 100,000 BTU gas furnace with the old one taken out, typically $3,950.
How much is a high-efficiency furnace?
About $4,850 to $5,700 for a 100,000 BTU high-efficiency furnace, against $3,700 to $4,350 for a standard one of the same size.
How much is a smaller furnace?
About $3,250 to $3,900 for a 60,000 to 75,000 BTU furnace.
Should the air conditioner be replaced at the same time?
A split central air system’s indoor coil sits on the furnace and uses its blower and ducts, so the two can be done in one visit. The AC installation cost guide prices central air by size.