Introduction
Ductwork is the hidden half of an HVAC quote — and the part homeowners understand least. A duct replacement can cost anywhere from a couple thousand dollars for a small accessible system to well into five figures for a large home with difficult access, and the range mostly comes down to linear footage, material, labor access, and how much of the old system must come out first. Knowing the typical planning ranges before you call contractors is what keeps a quote honest.
Before pricing anything, you need to know what size ducts the system actually requires — undersized ducts quoted cheap are no bargain. The Duct Size Calculator gives you the diameters first, so every number below can be applied to a real layout instead of a guess. Costs in this guide are typical US planning ranges; your region’s labor rates and access conditions move them up or down.
Typical Ductwork Cost Ranges
All figures are typical US planning ranges (materials + labor, installed), and they vary significantly by region, home size, and how accessible the duct locations are:
| Project | Typical planning range |
|---|---|
| Full ductwork replacement (typical home) | $2,000–$7,500 |
| New ductwork (new construction or addition) | $3,000–$10,000+ |
| Per linear foot, flexible duct installed | $25–$50 |
| Per linear foot, rigid sheet metal installed | $35–$75 |
| Single new supply runout (branch) | $200–$500 |
| Adding a return air run | $500–$1,500 |
| Manual duct sealing (mastic) | $300–$800 |
| Aerosol duct sealing | $1,500–$2,500 |
| Duct cleaning | $300–$500 |
| Room-by-room load calculation (Manual J), standalone | $200–$500 |
Most full replacements for average single-family homes land in the $3,000–$6,000 band. Quotes below $2,000 for a whole-house replacement deserve scrutiny — something (sealing, insulation, returns, permits) is probably missing. Material choices drive the spread: compare them in the material guide.
What Drives the Cost Up or Down
Access and labor
Labor is typically 60–70% of a duct job. Ducts in an open basement or a tall accessible attic are fast to replace; ducts buried in a low crawlspace, sealed inside finished walls, or routed through a hot tight attic take far longer — and that time is billed hourly at $75–$150 per hour in most US markets, higher in major metros. If your home needs drywall opened and patched to reach the ducts, add that trade’s cost too.
Total linear footage and number of runs
Cost scales with feet of duct and number of takeoffs, boots, and registers. A compact single-story ranch with a central air handler needs far less duct than a sprawling two-story with long runs to far bedrooms — which is also why long-run homes need larger (pricier) duct diameters to hold the friction rate. Size every run first with the estimating guide so quotes are based on your layout, not a rule of thumb.
Material choice
Flexible duct is the cheapest installed (fast to run, minimal fittings); rigid galvanized sheet metal costs more in both material and labor but lasts decades and holds its friction characteristics. Fiberglass ductboard sits in the middle on cost and adds built-in insulation. In unconditioned attics and crawlspaces, insulation level (R-6 vs R-8) adds a modest premium that pays back in energy savings.
Removal and disposal of old ductwork
Tear-out of old ducts — especially old fiberglass ductboard or asbestos-era materials — adds labor and disposal fees. If ducts run through finished spaces, factor in drywall repair and repainting, which contractors often exclude from the HVAC quote.
Permits, testing, and extras
Permits typically add $100–$400 depending on jurisdiction. Duct leakage testing, increasingly required for new installs, adds a few hundred dollars. Zoning dampers, upgraded filtration, and UV or media air cleaners are common add-ons that inflate the “duct quote” — price them separately. See the code compliance guide for what’s typically required versus optional.
How Sizing Affects What You Pay
Correct sizing changes the quote in both directions:
- Undersized ducts are a false economy. Smaller duct costs less on the quote but forces the blower to work against high static pressure — higher energy bills, more noise, shorter equipment life, and rooms that never reach temperature. The “savings” evaporate in the first few years.
- Oversized ducts waste material and hurt comfort. Air moving too slowly doesn’t throw properly from registers or mix in the room, and you paid for metal you didn’t need. Oversizing also makes balancing harder.
- Returns are the cheapest performance upgrade. An undersized return chokes the whole system; adding return capacity is usually a few hundred dollars and fixes airflow problems that no supply-side work can.
- Sealing beats upsizing. If the issue is lost air rather than small ducts, sealing existing ducts ($300–$800 manual, $1,500–$2,500 aerosol) delivers more comfort per dollar than replacing the system.
The common mistakes guide covers the sizing errors that turn into expensive rework.
Repair vs Replace: The Decision Math
Replace the duct system (rather than patching it) when several of these are true:
- Ducts are 20+ years old, especially flex duct with crumbling insulation or ductboard that’s delaminating.
- Leakage testing or inspection shows widespread disconnected, crushed, or missing sections — not one bad joint.
- The system was never sized properly (chronic hot/cold rooms, whistling registers, high static pressure readings).
- You’re replacing the furnace/air conditioner — new equipment on bad ducts inherits every old problem, and it’s the cheapest time to do both.
- Remodeling opens walls or ceilings anyway, making access nearly free.
Repair and seal when the ducts are fundamentally the right size and material but have isolated leaks, a disconnected joint, or missing insulation in spots. A few hundred dollars of mastic and insulation on sound ducts is one of the best returns in home energy work.
Getting and Comparing Quotes
- Get three quotes from licensed HVAC contractors — and make sure each one includes a room-by-room load calculation, not just equipment tonnage.
- Ask for the design friction rate and static pressure budget. A contractor who can state the friction rate, total effective length, and available static pressure has actually designed the system; one who can’t is guessing.
- Compare scope line by line: linear feet and sizes, material type and gauge, insulation R-value, sealing method (mastic vs tape), number of supplies and returns, register/ grille types, permits, testing, and patch/repair exclusions.
- Check what’s excluded: drywall patching, painting, old duct disposal, and permit fees are the classic surprise add-ons.
- Never accept “same size as what’s there.” Existing ducts may be the problem — verify sizes against the calculator before authorizing like-for-like replacement.
Whether to manage any of this yourself or hand it to a contractor is covered in the DIY vs pro guide.
Related Guides
- Duct Size Calculator FAQ — quick answers to the most asked duct sizing questions.
- Pro Tips — design and installation judgment from the trade.
- Hypothetical Case Study — a worked undersized-duct scenario with the math shown.
- Duct Sizing Checklist — every step to verify before you buy ductwork.
- Code Compliance — permits, sealing, and insulation requirements.
Get Your Number
Every honest duct quote starts from the same place: the right sizes for your airflow, friction rate, and longest run. Run your layout through the Duct Size Calculator first, then hand contractors a sized plan to price — quotes on your numbers are comparable; quotes on their guesses are not. Confirm permit and testing requirements with your local building authority before work starts.
Disclaimer: Calculator results and cost figures are planning estimates based on the dimensions you enter. Actual duct sizing and project costs depend on your system’s airflow requirements, equipment static pressure, duct material, regional labor rates, and local code. Verify with a licensed HVAC professional, and consult your local building authority for code and permit decisions.
