Understanding your result
The headline is the installed price range, with the midpoint and the system described in the sub-line. The stats split it into low, midpoint and high, and the bars show how the midpoint divides between equipment and installation, ductwork and the permit. The table carries every step: the base range and its source, the equipment and labour halves of it, the ductwork, the permit and the total.
Read the range as the band within which most quotes for this job fall. A quote near the low end is usually a minimum-efficiency unit with the bare essentials; one near the high end includes a premium brand, a longer warranty, a new line set or duct work. A quote outside the band is not necessarily wrong but is worth asking about, and the guide to reading an HVAC quote lists the questions.
The tonnage should come from a load calculation, not from the old unit: the central AC size calculator gives a first estimate. For a furnace alone, the furnace installation cost calculator goes into fuels, venting and gas lines; for a heat pump, the heat pump installation cost calculator adds electrical upgrades and rebates; and for new ducts the ductwork cost calculator prices them by the foot.
How we calculate this
The base ranges are the published 2025 figures named in the result: HVAC.com and Bob Vila for air conditioners, the 2025–26 furnace guides for gas furnaces, contractor ranges and EnergySage’s marketplace data for ducted heat pumps, and the cold-climate heat pump guides. The size, tier and region factors are our multipliers, set out here so they can be checked; they reflect the per-ton price tables and regional labour differences in the same guides. The equipment share of about half is typical of itemised quotes. The efficiency tiers and what they mean for running cost are on the efficiency ratings table, and the duct sizes behind a duct replacement on the duct size chart.
The assumptions behind the numbers
| Assumption | Value | Where it comes from |
|---|---|---|
| Central AC, 3 tons | $3,300 to $7,800 | HVAC.com 2025 (typical $5,750); Bob Vila via HomeServe $3,882 to $7,903 |
| Gas furnace, 80% | $3,000 to $6,500 | 2025–26 furnace cost guides (most homes $2,800 to $6,500; average about $5,500) |
| AC and furnace together | $7,000 to $13,500 | Sum of the two less shared labour (our judgement, about 5%) |
| Ducted heat pump | $7,000 to $15,000 | Contractor ranges $6,500 to $12,500; guides $12,000 to $18,000; EnergySage 2025 ducted average $15,326 after incentives |
| Cold-climate heat pump | $10,000 to $20,000 | 2025 cold-climate heat pump guides |
| Duct replacement | $4,000 to $14,000 | 2025 ductwork guides (Fixr, PickHVAC) |
| Size, tier, region factors | 12% per ton; 1.15 and 1.35; 0.85 and 1.2 | Our multipliers from per-ton tables and regional labour differences in the same guides |
| Permit | $250 to $500 | Typical municipal mechanical permit (our range) |
Assumptions last reviewed October 8, 2026.
The calculator does not include electrical panel upgrades, a new thermostat beyond a basic one, zoning, air cleaners, humidifiers, removal of asbestos duct insulation, or crane lifts for rooftop units, and it does not subtract rebates. Prices change with refrigerant transitions and tariffs; the ranges are reviewed yearly. The guide to what HVAC installations cost explains the ranges and what moves them, and the guide on repairing or replacing covers the decision that comes first.
Two worked examples
A straight air conditioner swap
3-ton central AC, minimum efficiency, existing ducts and furnace reused, average-cost area, permit pulled.
- Base range: $3,300 to $7,800
- Factors: 1.0 size, 1.0 tier, 1.0 area
- Permit: $250 to $500
- Total: $3,550 to $8,300, midpoint $5,925
- About half is equipment ($1,650 to $3,900)
A quote of $6,200 for this job is right in the middle; one of $3,200 probably leaves out the permit or reuses the old line set, and one of $9,500 is worth questioning unless it includes a higher tier or duct work.
A full system in a high-cost city
AC and furnace together, 4 tons, mid tier, ducts sealed and modified, high-cost metro area, permit.
- Base range: $7,000 to $13,500
- Equipment and installation: × 1.12 × 1.15 × 1.2 = $10,819 to $20,866
- Duct repair: $1,000 to $2,500 × 1.2 = $1,200 to $3,000
- Total: $12,250 to $24,400, midpoint $18,325
The size, the tier and the city each add 12 to 20%, and together they nearly double the base. Before accepting 4 tons, check the load; if a Manual J says 3.5 tons, the same job drops by about $1,000, and the smaller system will dehumidify better.
Where to find your inputs
System and size. From the quote, or the outdoor unit’s model number (36 = 3 tons). For a new size, use a load calculation.
Tier. The SEER2 and AFUE on the quote: 13.4 to 14.3 SEER2 and 80% AFUE is the minimum tier; 15.2 to 16 SEER2 or a two-stage furnace the mid tier; 17 SEER2 and up with variable speed, or 96% AFUE and up, the high tier.
Ductwork. Reuse if the ducts tested tight and the rooms are comfortable; repair if they leak or a room is starved; replace if they are damaged, uninsulated flex in an attic or far too small.
Region. High for the Northeast, California, the Pacific Northwest and big metros; low for rural areas of the South and Midwest.
Common mistakes
- Comparing quotes for different sizes. A 4-ton quote and a 3-ton quote are different jobs; settle the size first.
- Missing line items. Check for the permit, line set, pad, disconnect, thermostat and haul-away.
- Choosing on price alone. Installation quality decides performance more than the brand.
- Skipping the load calculation. Ask for the Manual J; it is part of a professional quote.
- Ignoring the ducts. A new system on leaky ducts underperforms.
- Forgetting rebates. State and utility programmes can change which tier is the better buy.
Questions people ask
- How much does it cost to replace central air?
- For a 3-ton air conditioner at minimum efficiency, reusing the ducts and the furnace, 2025 cost guides put the installed price at about $3,300 to $7,800, with a typical job near $5,750 (HVAC.com). Adding a permit brings the calculator's range to about $3,550 to $8,300. A mid-tier two-stage unit adds about 15%, a variable-speed unit about 35%, and a high-cost metro area about 20%.
- How much does it cost to replace a furnace and air conditioner together?
- About $7,000 to $13,500 for a 3-ton system with an 80% furnace in an average-cost area, before ductwork, because the two share labour, the coil and the blower connection. A 4-ton mid-tier system with some duct repair in a high-cost area comes to about $12,250 to $24,400. Replacing both at once usually costs less than doing them a few years apart.
- What is included in an HVAC replacement quote?
- Equipment (outdoor unit, indoor coil or air handler, furnace), removal and disposal of the old equipment, refrigerant, a new or flushed line set, a pad, the electrical disconnect and whip, the thermostat, condensate line, start-up and commissioning, a permit, and the manufacturer's and installer's warranties. Equipment is typically about half of the price. Ductwork, electrical panel upgrades and venting changes are usually extras and should be itemised.
- Why do HVAC quotes vary so much?
- Brand and efficiency tier, the size the contractor proposes (which should come from a Manual J, not the old unit's label), what is included (line set, pad, thermostat, permit, duct sealing), labour rates, and the contractor's overhead and warranty. Quotes for the same job routinely differ by 30 to 50%. A quote far below the others often leaves out the permit or the line set; one far above may include ductwork or a premium brand.
- Do I need to replace the ductwork with a new system?
- Only if it is leaky, undersized, damaged or badly laid out, which a duct leakage test and a Manual D check show. Reusing sound ducts saves $4,000 to $14,000; sealing and modifying them typically costs $1,000 to $2,500. Putting a new high-efficiency system on ducts that leak 25% into an attic throws away much of what the efficiency bought.
- Does the region really change the price that much?
- Yes. Labour is about half of an HVAC job, and labour rates in high-cost metros are 15 to 25% above the national average, and in rural areas of the South and Midwest about as much below. Equipment prices vary less. The calculator applies 0.85, 1.0 or 1.2 to the whole job, which is our rounding of the regional differences reported in 2025 cost guides.