A new furnace installed typically runs $4,000 to $8,000 for a standard 80% AFUE unit, and $5,500 to $11,000+ for a high-efficiency 90%+ AFUE furnace with two-stage or modulating heat output. Brand matters less than most homeowners expect. What actually moves the number is the furnace’s stage type, your home’s heating load, and how much work the installer has to do around the unit: venting, gas line, electrical, permits, and hauling the old one away.
This page covers replacing the furnace alone. If your central AC is also near the end of its life, doing both at once is often the better financial call. See “when furnace-only replacement is a false economy” below, and the full breakdown at furnace and AC replacement cost.
Furnace cost by efficiency and stage type
Stage type is the single biggest lever on price after efficiency tier. A single-stage furnace fires at one output level: full on or off. A two-stage furnace has a low setting for mild days and a high setting for cold snaps. A modulating furnace adjusts its burner output in small increments, holding a steadier temperature and running quieter and longer at low fire.
| Furnace type | AFUE | Typical installed cost |
|---|---|---|
| Standard efficiency, single-stage | 80% | $3,800 – $6,000 |
| High-efficiency, single-stage | 90%+ | $4,500 – $7,500 |
| High-efficiency, two-stage | 90%+ | $5,500 – $9,000 |
| High-efficiency, modulating | 95%+ | $7,500 – $12,000+ |
Two-stage and modulating furnaces cost more because the control board, gas valve, and blower are all more sophisticated than a single-stage unit’s, and because the extra comfort is genuinely worth something in a climate with a long heating season. In a mild climate with short, infrequent heating cycles, the case for paying $1,500–$4,000+ more is comfort, not a fast energy-cost payback. You can check whether a specific model is ENERGY STAR certified at that efficiency tier through ENERGY STAR’s certified furnace finder.
Furnace cost by home size
Furnace output is rated in BTUs, and the right output depends on climate zone, insulation, window area, and ceiling height, not square footage alone.
| Home size | Typical output needed | Typical installed cost |
|---|---|---|
| Under 1,500 sq ft | 40,000–60,000 BTU | $3,500 – $5,500 |
| 1,500–2,500 sq ft | 60,000–100,000 BTU | $4,500 – $7,500 |
| 2,500–3,500+ sq ft | 100,000–140,000 BTU | $6,000 – $10,000+ |
Use these as a rough starting point, not a substitute for a real load calculation. A furnace should be sized off a room-by-room heat loss calculation (ACCA Manual J), not off “whatever the old one was rated.” An oversized furnace short-cycles: it fires hard, satisfies the thermostat fast, and shuts off again and again instead of running one longer, steady cycle. That wastes energy, wears out the ignition system and blower faster, and leaves rooms far from the furnace underheated. See HVAC short cycling for what that pattern looks like and why it happens on furnaces as well as AC systems.
What’s actually in a furnace installation quote
The furnace itself is one line item. A full quote should also account for:
- Venting. An 80% AFUE furnace vents through the existing metal flue. A 90%+ AFUE condensing furnace vents through new sealed PVC or CPVC intake and exhaust pipe, run to an exterior wall: a different job, not just a different part. Budget $300–$1,500 for this when switching efficiency tiers.
- Gas line. If the new furnace’s input BTU rating differs meaningfully from the old one, the gas line may need resizing. Minor adjustments run $150–$500; a full line replacement or relocation runs higher.
- Electrical. Furnace control boards, inducer motors, and especially variable-speed (ECM) blowers can require a dedicated circuit or a different disconnect than the old unit had. If your furnace’s blower motor specifically is the failing part rather than the whole system, see furnace blower motor replacement cost before assuming you need a full replacement.
- Permits. Most municipalities require a permit and inspection for furnace replacement, typically $150–$500. Don’t sign a bid that quietly skips it.
- Disposal. Hauling away the old furnace should be included in the quote, not a surprise add-on.
Why two quotes for the same job can differ by thousands
Three homeowners comparing bids for what looks like “the same furnace” routinely see spreads of $2,000–$4,000 or more. The gap is almost never about which brand’s name is on the cabinet. It’s about:
- Equipment tier. “High-efficiency” spans a wide range: a base 90% single-stage unit and a 97% modulating unit are both “high-efficiency” and can differ by $4,000+.
- Whether a real load calculation was done. A contractor who measures your home and calculates the load (ACCA Manual J) may spec a different, sometimes smaller and cheaper, furnace than one who just matches the old unit’s rating.
- Whether venting is being redone or reused. Switching from 80% to 90%+ AFUE forces new venting; staying at 80% AFUE doesn’t. A bid that’s cheaper because it’s quietly keeping you on the same tier isn’t necessarily wrong, but it needs to be an informed choice, not a surprise.
- What’s excluded. A permit, a load calculation, disposal of the old unit, or a real labor warranty: any of these missing from the cheap bid explains most of the gap by itself.
Before signing anything, run the bid through the questions in the new HVAC system decision guide, which covers the broader repair-vs-replace call this decision usually sits inside of.
When furnace-only replacement is a false economy
Furnace and AC aren’t independent machines in a standard split system. The furnace’s blower moves the air the AC cools, across a coil that typically sits on top of the furnace cabinet. That coupling changes the math in a few specific situations:
- The AC is roughly the same age and near end of life too. Replacing only the furnace now all but guarantees a second mobilization (a second service call, a second round of labor pricing) within a few years. Combining the jobs commonly saves 15–25% versus doing them separately, because the crew shows up once. See the full combo math at furnace and AC replacement cost.
- The new furnace changes blower airflow enough to affect the AC’s rated performance. A new furnace’s blower may move air at a different CFM than the old one. If your AC was sized and rated against the old blower’s airflow, a mismatch can mean the AC no longer delivers its rated efficiency, even though nothing about the AC itself changed.
- You don’t have central AC yet and are considering adding it while the furnace work is already underway. That’s a different scope than a furnace-only swap. See central air installation cost for what installing AC into a system that doesn’t have it currently runs.
- The AC is genuinely young (under 8–10 years) and healthy. In that case, replacing the furnace alone is the right call. See AC unit replacement cost for what that project looks like on its own, later, when the AC actually needs it.
Rebates and financing, at a high level
Three levers typically apply to a furnace replacement, and all three are worth checking before you sign:
- Federal tax credit. The Energy Efficient Home Improvement Credit (Section 25C) covers a share of the cost of qualifying high-efficiency equipment, up to an annual cap that’s set and adjusted by the IRS. Check the current cap and qualifying criteria at IRS.gov and ENERGY STAR’s federal tax credit page before assuming a number, since both change year to year.
- Utility rebates. Many electric and gas utilities offer rebates for high-efficiency furnace installations, separate from the federal credit. These vary by utility and region, so check your utility’s website directly.
- Contractor or manufacturer financing. Promotional 0%-APR financing is common on larger HVAC jobs. Read the terms before signing: some plans charge deferred interest retroactive to the purchase date if the balance isn’t paid off within the promotional window, which can turn a “free” loan into an expensive one.
None of these change the installed price on the quote itself. They change what you net out after the job, and only for equipment and installations that actually qualify. Confirm eligibility before you count the savings.
How to sanity-check a furnace bid
Before signing, get the answers to these in writing:
- Was a load calculation done, or is the new unit “the same size as the old one”? A real number (ACCA Manual J) beats a guess.
- What’s the exact model number, AFUE, and stage type? “High-efficiency” isn’t a spec. The model number is.
- Is venting material and routing specified, if you’re changing efficiency tiers?
- Is the permit included, and who’s scheduling the inspection?
- Is disposal of the old furnace included?
- What’s the labor warranty, in writing, separate from the manufacturer’s parts warranty?
- What’s the AHRI reference number for this equipment’s rated output? You can verify any number against the AHRI Directory.
If the furnace is old but a specific part just failed, replacement may not be the right call yet. A cracked or overheating control sequence often traces back to a furnace flame sensor that needs cleaning, or a failed hot surface igniter. Both are common, inexpensive fixes that get mistaken for “the furnace is dying.” A routine HVAC tune-up ($75–$200) is also the cheapest way to find out whether you’re looking at a repair or a real replacement before you get quotes for either.
Timing: emergency replacement vs. planned replacement
Furnace failures cluster in cold weather, which means furnace replacement demand, and pricing power, shifts toward installers in the coldest months. An emergency January replacement, done same-day or next-day because the house is genuinely cold, gives you far less room to get multiple bids, verify a load calculation, or negotiate scope. A planned replacement in late summer or early fall, before the furnace actually fails, gives you the opposite: more contractor availability, more time to compare bids properly, and less pressure to accept the first number you’re quoted.
If your furnace is in the age range where replacement is a “when,” not an “if,” getting ahead of a cold-weather failure is worth the planning effort by itself, independent of any price difference. See the full HVAC cost index for how furnace replacement compares to other HVAC costs.
Frequently Asked Questions
Q: How much does a new furnace cost installed?
A: Most homeowners pay $4,000 to $8,000 installed for a standard 80% AFUE furnace, and $5,500 to $11,000+ for a high-efficiency 90%+ model with two-stage or modulating heat output. The exact number depends on your home’s heating load, whether venting or electrical work is required, and local labor rates.
Q: Is a two-stage or modulating furnace worth the extra cost?
A: In a cold climate with a long heating season, most homeowners find it worth it: two-stage and modulating furnaces run longer, gentler cycles that hold a tighter temperature and use less energy at partial load. In a mild climate with short, infrequent heating cycles, the extra $1,500–$4,000+ over a single-stage unit takes a long time to pay back in energy savings alone; the case there is comfort, not payback speed.
Q: Can I replace just the furnace without replacing the AC?
A: Yes, furnace and AC don’t have to be replaced together. The one thing worth checking is airflow: your furnace’s blower moves the air across the AC’s evaporator coil, so a meaningful change in blower CFM can affect how the existing AC performs. See furnace and AC replacement cost for when doing both at once actually saves money instead.
Q: How long does a furnace installation take?
A: A straightforward like-for-like swap is typically a one-day job. Add a half-day to a full day if the new unit needs different venting (switching from 80% to 90%+ AFUE), a gas line change, or electrical work.
Q: What size furnace do I need?
A: Size it to a room-by-room heat loss calculation (ACCA Manual J), not to the old furnace’s rating or a flat square-footage rule of thumb. An oversized furnace short-cycles, running short, hot bursts instead of longer, steady ones, which wastes energy and wears out components faster. See HVAC short cycling for what that looks like in practice.
Bottom line
The furnace itself is only part of the bill. Efficiency tier and stage type set the floor, home size and load calculation set the equipment spec, and venting, gas line, electrical, and permits set how much work surrounds the box. Get the load calculation done, get the model number and AHRI reference in writing, and check whether your AC’s age makes this a one-project year instead of two.
