Construction & home
Furnace Replacement Cost Calculator
Work out a realistic furnace replacement cost for your home from fuel type, square footage, AFUE efficiency, equipment tier and region. The estimate splits equipment from labour so you can see where the money actually goes, and section 03 explains what a contractor's quote should itemise.
This is a planning bracket, not a quote. Real prices swing hard on things no calculator can see, and section 09 is honest about which ones.
Only the space the furnace actually heats.
Changes both the size you need and local labour rates.
Estimated total
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Furnace size
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Equipment
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Labour
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Extra work
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Where the money goes
What to do with this number
Typical cost by home size
| Home size | Furnace size | Typical range |
|---|
Prices last verified against contractor sources: ____________
What does a new furnace cost in 2026?
Most whole-job furnace replacements land somewhere between $3,000 and $9,000 including installation, with gas units clustered around the middle of that and electric at the lower end. The spread is wide because the furnace itself is often less than half the bill.
Natural gas
The most common choice in American homes. Cheap to run in most areas, moderate to buy, and the widest range of models to pick from.
Electric
Cheapest to buy and install because there is no combustion, no flue and no gas line. Usually the most expensive to run.
Oil
Mostly the Northeast. Higher equipment and labour cost, and running cost tracks heating oil prices, which move a lot.
Propane
For homes with no gas main. The furnace is much like a gas one, but the fuel usually costs more per unit of heat.
The single biggest swing factor is not the furnace. It is whether your ductwork needs work. A straight swap into good existing ducts is at the bottom of the range. A replacement that also needs ducts resized or replaced can add several thousand on its own, which is why it is a separate tick box in step 4.
How this furnace replacement cost calculator works
Four inputs, in the order a contractor would ask about them.
- Fuel type sets the base equipment and labour range. Electric skips the efficiency step entirely.
- Square footage and region decide the furnace size in BTU, and adjust labour for local rates.
- AFUE and equipment tier add to the equipment cost. A condensing high-efficiency unit costs meaningfully more than a standard one.
- Additional work is added at both ends of the range, so ticking a big item widens the estimate rather than pretending to new precision.
That last point matters and the previous version of this page got it wrong. Ductwork replacement genuinely spans $1,400 to $5,600. Reporting it as a single midpoint made the total look far more certain than it is. Now the low end adds to the low end and the high to the high, which is what a range is for.
Furnace installation cost: equipment versus labour
On a typical job the furnace unit is roughly half to two thirds of the bill and labour is the rest. That surprises people, but a furnace swap is a day or two of skilled work involving gas, electricity and flue gases, usually with a permit and an inspection.
What a proper quote itemises
- The exact model number and its AFUE rating, not just "high efficiency"
- The BTU output of the unit being fitted
- Labour as its own line, with the number of days
- Whether the price includes the permit and inspection
- Any ductwork, venting or electrical work, priced separately
- Removal and disposal of the old unit
- The warranty, both on the part and on the labour, which are different things
A quote that is one number with no breakdown is not a quote, it is a figure. Ask for the itemised version before comparing anything.
What size furnace do I need?
Furnace size is measured in BTU per hour. The rough starting point used by this calculator is:
That gives a ballpark, then the result is rounded to the nearest standard furnace size, because furnaces are sold in fixed increments.
Bigger is not better
An oversized furnace short cycles: it blasts to temperature, shuts off, and repeats. That gives uneven heat, more wear on the parts, and often a higher bill than a correctly sized unit. It is one of the most common installation mistakes.
What this rule of thumb cannot see: insulation levels, window quality and quantity, ceiling height, how airtight the house is, and which direction it faces. A contractor should perform a proper heat load calculation, known in the trade as a Manual J, before deciding the size. If yours sizes the furnace by square footage alone, that is worth questioning.
AFUE ratings, and when high efficiency pays back
AFUE stands for Annual Fuel Utilisation Efficiency. It is the percentage of the fuel that becomes heat in your house rather than going up the flue. An 80% AFUE furnace turns 80 cents of every fuel dollar into warmth.
80% AFUE
Standard efficiency, cheapest to buy, vents through a conventional flue. Still a sensible choice in a mild climate or a home you plan to sell soon.
92 to 95% AFUE
Mid tier, usually a two-stage burner that runs gently most of the time and hard only when needed. Quieter and steadier as well as cheaper to run.
96 to 98% AFUE
Condensing furnaces, which extract heat from the exhaust. They need PVC venting and a condensate drain, so installation costs more, not just the unit.
How to think about payback rather than guess at it. Take the extra cost of the higher-efficiency unit, then work out your annual heating spend and multiply it by the efficiency gain. Going from 80% to 96% cuts fuel use by roughly a sixth, so on a $1,500 annual heating bill you save around $250 a year. Divide the extra cost by that and you have your payback in years, based on your bill rather than someone else's average. In a cold climate with high fuel costs it usually makes sense. In a mild one it often does not.
Gas furnace replacement cost by home size
About these figures. They are typical installed ranges for a straightforward replacement, excluding ductwork. They are a planning aid, not quotes, and they have not been verified against a named pricing source from this session. Get three local quotes before committing to any number here.
Last verified against contractor pricing sources: ____________
| Home size | Furnace size | Typical installed | Can reach |
|---|---|---|---|
| Under 800 sq ft | 40,000 BTU | $2,500 to $3,800 | $6,000 |
| 800 to 1,200 sq ft | 60,000 BTU | $2,800 to $4,200 | $7,000 |
| 1,200 to 1,600 sq ft | 80,000 BTU | $3,200 to $4,800 | $8,000 |
| 1,600 to 2,000 sq ft | 100,000 BTU | $3,800 to $5,500 | $9,200 |
| 2,000 to 2,500 sq ft | 120,000 BTU | $4,400 to $6,400 | $10,500 |
| 2,500 sq ft and up | 140,000 BTU | $5,000 to $7,500 | $12,000 |
When to replace a furnace rather than repair it
Age past about fifteen years
Most gas furnaces run fifteen to twenty years. Past fifteen, money spent on repairs is money spent on a unit you will replace soon anyway.
The repair costs more than a third of a new one
A common rule of thumb: multiply the repair cost by the age of the furnace in years. If it beats the price of a replacement, replace it.
A cracked heat exchanger
Not a repair decision. A cracked exchanger can leak carbon monoxide into the house, and on an older furnace the part often costs close to a new unit. Replace it.
Rooms that never match the thermostat
Uneven heat usually means the furnace is the wrong size or the ducts are wrong, not that the unit has failed. Worth diagnosing before spending on either.
Rising bills with no change in habits
A furnace losing efficiency shows up on the bill before it shows up as a breakdown.
Safety, not budgeting. If you smell gas, hear a persistent rumble after the burner shuts off, see soot around the unit, or your carbon monoxide alarm sounds, stop reading cost guides. Leave the house and call your gas utility's emergency line. No estimate on this page is worth staying inside for.
Furnace replacement cost FAQ
Limits, sources and disclaimer
What this calculator cannot see
The condition of your existing ductwork, how accessible the furnace location is, your insulation and windows, whether the flue needs relining, local permit costs, what your specific contractors charge, and whether anything unexpected turns up once the old unit comes out. Any of these can move a real quote well outside the range shown here. Treat the output as a bracket for a conversation, not a budget.
About the figures
The price ranges are typical installed costs for a straightforward replacement and have not been verified against a named pricing source from this session, which is why sections 06 and the results table each carry a blank verification line. An earlier version of this page displayed "2026 verified pricing" and credited six named cost websites. That claim has been removed until the figures are actually checked, in line with the rule on the Editorial Policy that a source is only named if it was read.
Not professional advice
This page is informational. It is not a quote, not an offer, and not a substitute for a licensed HVAC contractor assessing your home. Furnace work involves gas, electricity and combustion products, and it is not a do-it-yourself job. Always use a licensed, insured installer and pull the required permits. For the current federal tax position, check the IRS Energy Efficient Home Improvement Credit page directly.
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