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Calculator Methodology

How the Ductwork Cost Calculator estimate works

Ductwork can be the hidden line item that decides whether a new HVAC system actually performs.

This estimate is for planning. Actual results may change based on local pricing, contracts, title practice, lender disclosures, insurance documents, inspection findings, hidden conditions, timing, and professional review.

Use the calculator Build decision packet

Inputs used

Defaults are planning placeholders, not recommendations.

Conditioned square feet
Default: 2200 sq ft
Best description of the current setup
Default: gas-furnace-ac
A rough answer is fine. The point is to avoid replacing good furnace/blower/duct parts just because cooling failed.
Scope you want to price
Default: full
What the homeowner sees
Default: cooling-dead
Use symptoms and what you were told. You do not need to know the failed part.
Refrigerant label or tech claim
Default: unknown
If the contractor says "Freon is phased out," choose R-22 only if they identified it on the unit or paperwork.
Cooling coil / AC age if known
Default: 16 yrs
A best guess is enough. If unknown, use the age of the outdoor AC or the last major replacement.
What the quote or tech says
Default: no-quote
This is about what you were told, not what is actually true yet.
Furnace / blower age if known
Default: 8 yrs
If heat worked well last winter, the furnace/blower may still be useful even when cooling failed.
Mini-split zones or heads
Default: 4 zones
Mini-splits are planned by room/zone and BTU, not by pretending one wall head cools the whole home.
Efficiency tier
Default: standard
Ductwork scope
Default: full
Install complexity
Default: normal
Expected rebates or credits
Default: 0 $

What is included

  • The visible inputs listed on the calculator page.
  • The assumptions shown below the calculator.
  • A planning estimate based on the calculator family, not a binding quote, contract, appraisal, insurance settlement, title statement, or lender disclosure.
  • Input: Conditioned square feet.
  • Input: Best description of the current setup.
  • Input: Scope you want to price.
  • Input: What the homeowner sees.
  • Input: Refrigerant label or tech claim.
  • Input: Cooling coil / AC age if known.
  • Input: What the quote or tech says.
  • Input: Furnace / blower age if known.
  • Input: Mini-split zones or heads.
  • Input: Efficiency tier.
  • Input: Ductwork scope.
  • Input: Install complexity.

What is excluded

  • Final contractor pricing, local permit interpretation, lender underwriting, title-company settlement, insurance claim approval, tax advice, legal advice, or property-specific professional judgment.
  • Every local custom, contract term, hidden condition, inspection finding, market shift, and timing issue.
  • Guaranteed savings, resale value, coverage, approval, or final cash due.
  • Full Manual J design, in-person HVAC diagnosis, roof inspection, structural inspection, code inspection, or contractor warranty review.

What can make the estimate too low

  • Hidden damage, access difficulty, permit/code requirements, disposal, electrical, gas, duct, decking, flashing, ventilation, or warranty scope is not included.
  • The quote is a low base price with change orders likely.
  • Emergency timing reduces quote leverage.

What can make the estimate too high

  • A narrower repair, partial replacement, roof-over, owner-supplied material path, rebate, or scope trim is safe and documented.
  • Access is easier, hidden conditions are absent, or the project is bundled efficiently.
  • A second quote proves the first quote included unnecessary scope.

Assumptions

  • Calculator treats ductwork as part of the HVAC project range.
  • Ask for separate duct scope, insulation, sealing, and balancing language.

When to verify before acting

  • Before signing a contractor quote, purchase contract, listing agreement, loan document, title document, insurance claim document, or association document.
  • When a result depends on local custom, contract language, code, warranty, hidden conditions, eligibility, or professional judgment.
  • When the result changes whether you repair, replace, sell, buy, claim, finance, or walk away.