Estimate a ductwork budget from measured linear feet, opening counts, and quote prices while keeping fixed project charges separate.
Table of contents
How to use our Ductwork Installation Cost per Linear Foot Calculator
- Enter Total duct run length from the contractor takeoff or HVAC plan. Include both trunk ducts and branch runs.
- Enter the low and high prices from the quote in Low duct-run price and High duct-run price.
- Count Supply registers or boots and Return grilles or boots. Add separate opening prices in Advanced options only if they are not already included in the run price.
- In Advanced options, mark each fixed project item as included, excluded, or unknown. Enter a charge only when you have an amount from a quote or other project source.
- Check that the low estimate is no higher than the high estimate, then compare the fixed-charge-free price only against quotes with similar duct and opening scope.
Definitions
Total duct run length: The combined length of trunk ducts and branch runs, measured in linear feet.
Duct-run price: The installed price charged for each linear foot of ductwork. It may include different labor, material, and access conditions depending on the quote.
Supply register or boot: An opening and connection that sends heated or cooled air into a room.
Return grille or boot: An opening and connection that pulls room air back toward the HVAC equipment.
Fixed charge: A project charge that does not change directly with duct length, such as a permit, demolition, design, or drywall repair.
HVAC load and duct design: Separate planning work that can include Manual J load calculations and Manual D residential duct design. Manual D is an ACCA residential duct design method. [1]
Comparison price without fixed charges: The duct-run and opening charges divided by total duct length, with included fixed charges removed.
All-in price per linear foot: The installed project estimate divided by total duct length, including known fixed charges.
Common mistakes and quick fixes
Mistake: Using home square footage as Total duct run length.
Fix: Enter measured or quoted trunk and branch duct length in linear feet.
Mistake: Entering a High duct-run price lower than the Low duct-run price.
Fix: Increase the high price or correct the two quote amounts.
Mistake: Combining every opening into Supply registers or boots.
Fix: Count supply openings and Return grilles or boots separately.
Mistake: Adding an opening price even though it is already included in the Low duct-run price and High duct-run price.
Fix: Leave the matching supply-opening or return-opening price at $0 to avoid double counting.
Mistake: Marking Permit and inspection status as included without entering the quoted amount.
Fix: Enter the permit charge or mark it unknown until the contractor confirms the scope.
Mistake: Treating Fixed charges still marked unknown as part of the estimate.
Fix: The total excludes these items; ask about each one before using the estimate to choose a quote.
Limitations & Key Assumptions / Boundary Conditions
- The calculator uses only the prices, quantities, and fixed charges you enter. It does not create a local market price or adjust a rate for material, labor, access, or project type.
- Total duct run length must come from a plan, takeoff, quote, or measurement. Home square footage is not converted into duct length.
- Unknown and excluded demolition, permit, design, and drywall charges are left out of the installed totals. The actual project total can be higher if an unknown item is later included.
- The comparison price removes only the four fixed charge categories shown in Advanced options. Other fixed quote items can still affect a contractor's per-foot pricing.
- Supply and return prices should be $0 when those items are already included in the duct-run price. Otherwise, the estimate double counts them.
- This is a planning and quote-comparison calculation, not a duct sizing, airflow, code compliance, or contractor bid.
Methodology
How the calculation works
The calculator first prices duct length, then adds separately priced supply and return openings. It adds a fixed charge only when its status is set to Included. A charge marked Excluded or Unknown is not added.
low duct-run charge = total duct run length x low duct-run price
high duct-run charge = total duct run length x high duct-run price
low opening charge = supply count x low supply-opening price + return count x low return-opening price
high opening charge = supply count x high supply-opening price + return count x high return-opening price
low installed project estimate = low duct-run charge + low opening charge + fixed charges marked included
high installed project estimate = high duct-run charge + high opening charge + fixed charges marked included
comparison price without fixed charges = (duct-run charge + opening charge) / total duct run length
all-in price per linear foot = installed project estimate / total duct run length
Worked example
For 100 linear feet at $20 to $30 per foot, the duct-run charge is $2,000 to $3,000. With 8 supplies at $100 to $150 each and 2 returns at $200 to $300 each, opening work adds $1,200 to $1,800. If $800 of fixed charges are marked included, the installed estimate is $4,000 to $5,600. The comparison price without fixed charges is $32 to $48 per linear foot, while the all-in price is $40 to $56 per linear foot.
What can change the estimate
Prices entered in the calculator should already match the planned duct material, site access, local labor, and job scope. The calculation does not estimate these factors. Manual J and Manual D work may appear as a separate design charge; the calculator adds that charge only if it is marked included. [1]