You have a set of mechanical drawings with supply, return and exhaust duct routed across the plan. You need to know how many pounds of galvanized sheet metal, how many fittings, how much insulation and how many hangers the job carries before you can price it or check a subcontractor's number. That is what our hvac takeoff services measure.
- Deliverable
- Excel estimate + marked-up PDF plans
- Organized by
- CSI MasterFormat section
- Turnaround
- 24–48 hours for most projects
- Pricing
- ZIP-code-adjusted material and labor pricing
- Software
- Bluebeam Revu, PlanSwift, RSMeans data
We take off hvac ductwork by size, gauge and material from the mechanical plan, the mechanical schedule, the riser diagram and the spec section. Rectangular runs are measured in linear feet by width × height, converted to pounds using the gauge shown and standard sheet metal weight tables. Round and flat oval runs are measured in linear feet by diameter. Fittings are counted by type, size and gauge — elbows, tees, wyes, reducers, offsets and square-to-round transitions. Insulation and liner are measured in square feet by thickness. Dampers, access doors, hangers and roof curbs are counted each. VAV terminal units, diffusers and grilles are counted each from the schedule, and condensate drain runs are measured in linear feet where they fall inside the mechanical scope.
The result is organized by CSI MasterFormat Division 23 sections: 23 31 13 metal ducts, 23 31 16 duct liners, 23 33 13 dampers, 23 07 13 duct insulation and the rest. You get Excel and PDF files with a marked-up plan set showing what we measured and where, and a bill of materials you can drop into a bid package. Turnaround is 24–48 hours for most projects, with rush available. If your ductwork is part of a larger mechanical package, start with our HVAC Estimating Services page. For projects in specific states, see Texas estimating or California estimating.
As an hvac estimating company, we also support contractors who need an hvac estimate for contractors, ductwork takeoff services, or a full sheet metal takeoff. We work from Manual J and Manual D reports, ASHRAE tables, and any request for proposal documents you provide. We use PlanSwift and Bluebeam Revu with RSMeans data, and we can take off from as-built drawings or a Revit model. Send your plans through our Get an estimate page to start.
What our hvac takeoff services cover
This is a duct and fitting takeoff, not a full mechanical estimate. It measures the sheet metal, insulation, accessories and supports shown on the drawings. Equipment schedules, piping and controls are handled on the parent HVAC page.
Rectangular Duct
Galvanized rectangular duct 26 ga through 16 ga, measured by linear feet and converted to pounds using gauge weight tables.
LF · LBRound & Flat Oval
Spiral round and flat oval duct 26 ga through 20 ga, measured by linear feet and diameter, with transitions by equivalent diameter.
LF · EAFittings
Elbows, tees, wyes, reducers, offsets and square-to-round transitions counted by type, size and gauge.
EAInsulation & Liner
Ductboard, external wrap and acoustical liner measured in square feet by thickness, including facing and vapor retarder.
SFDampers
Volume dampers, backdraft dampers, fire dampers and smoke dampers counted by size and actuator type.
EAFlex Duct & Connectors
Flexible duct runs and flexible connectors measured by linear feet and diameter, including takeoffs and terminations.
LFHangers & Supports
Trapeze assemblies, hangers, seismic restraints and roof curbs counted by type and spacing requirement.
EASealants & Accessories
Duct sealant, mastic and tape by linear feet of joint per seal class, plus access doors and test-and-balance taps.
LF · EAWhat every hvac & duct takeoff takeoff includes
- Rectangular galvanized duct, 26 ga through 16 ga, by LF and LB
- Spiral round duct and fittings, 26 ga through 20 ga, by LF and EA
- Flat oval duct and transitions by equivalent diameter
- Rectangular fittings: elbows, tees, wyes, reducers, offsets, square-to-round
- Ductboard and externally wrapped insulation in SF by thickness
- Acoustical duct liner in SF by thickness
- Volume dampers, backdraft dampers, fire and smoke dampers by EA
- Flexible duct connectors and flex duct runs by LF and diameter
- Duct sealant, mastic and tape by LF of joint and seal class
- Hangers, trapeze assemblies and seismic restraints by EA
- Roof curbs, roof jacks, wall sleeves and gooseneck hoods by EA
- Test and balance taps and volume measuring stations by EA
How our hvac estimator performs a ductwork takeoff
- Review plans and specsWe read the mechanical plan, duct schedule, riser diagram and Division 23 spec section. We note the seal class (A, B or C), gauge schedule, insulation thickness and any seismic requirements. We flag discrepancies between the plan and schedule before measuring. For example, if the plan shows 26 ga but the spec calls for 24 ga on ducts over 24×12, we note it and ask which governs. We also check that the duct schedule matches the riser diagram for vertical runs.
- Measure duct runs by sizeUsing Bluebeam Revu and PlanSwift, we trace each duct run on the mechanical plan. Rectangular runs are measured in linear feet by width × height. Round runs are measured by diameter. We record the gauge from the schedule or spec and note where it changes along the run. For instance, a trunk duct that starts at 36×18 and reduces to 24×12 is measured as two separate lengths, each with its own gauge and weight per linear foot.
- Count fittings and accessoriesWe count every elbow, tee, wye, reducer, offset and transition by type and size. Dampers, access doors, turning vanes, flex connectors and test ports are counted each. Fire and smoke dampers are located on the life safety plan and matched to rated wall and floor assemblies. For example, a 1-1/2 hr rated corridor wall requires a fire damper with a sleeve and access door; we count all three items and reference the wall type.
- Measure insulation and linerExternal wrap and ductboard are measured in square feet by thickness. Acoustical liner is measured as internal surface area. We check whether both liner and wrap are specified on the same run, which happens on sound-sensitive jobs and changes the material and labor line. For instance, a run with 1" liner and 2" external wrap requires two separate material lines and additional labor for the liner installation before the wrap is applied.
- Calculate hangers and supportsHanger spacing is taken from the SMACNA table for the duct size, not a default. We calculate the number of trapeze assemblies, rods, clevis hangers and strut by run length. Seismic restraints are added where the jurisdiction adopts them, with bracing at spacing and at ends of runs. For example, a 48" wide duct requires hangers at 4 ft on center, while a 12" duct requires 8 ft on center; we apply the correct spacing to each run.
- Convert to pounds and build the takeoffRectangular and round duct lengths are converted to pounds using gauge and standard sheet metal weight tables. Fitting weights are derived from dimensions and gauge. The takeoff is organized by CSI MasterFormat section, with marked-up plans showing what we measured. For instance, 100 LF of 24×12 at 26 ga weighs approximately 750 LB, while the same length at 24 ga weighs approximately 900 LB; we show both the length and the weight for each line.
What we need from you
- Mechanical plansSupply, return, exhaust and outside air plans with duct routing and sizes. PDF preferred; we can work from CAD or Revit exports.
- Duct scheduleSchedule showing duct sizes, gauges, material and insulation thickness. If no schedule, we use the spec section and note assumptions.
- Spec section 23 31 00Gauge schedule, seal class, reinforcement requirements and any SMACNA compliance notes. This drives material and labor.
- Riser diagramVertical duct runs and shaft sizes. Often the only place where riser duct sizes and gauges are shown.
- Roof planRoof curbs, roof jacks and gooseneck hoods for exhaust and make-up air. These are frequently on the roof plan, not the mechanical plan.
- Life safety planRated wall and floor assemblies for fire and smoke damper locations. We match damper sizes and sleeves to the assembly.
- Seismic requirementsWhether the jurisdiction adopts seismic restraints for ductwork. If yes, we need the bracing details and spacing.
Sample HVAC quantity takeoff format
This is how the Excel file is organized. Each row is a CSI section with a line item, quantity, unit and the plan sheet we measured from.
| Section | Line item | Qty | Unit | Ref. |
|---|---|---|---|---|
| 23 31 13 | Rectangular duct 24×12, 26 ga, galvanized | 1,250 | LF | M-101 |
| 23 31 13 | Spiral round duct 14" dia, 24 ga | 480 | LF | M-102 |
| 23 31 13 | Rectangular elbow 24×12, 26 ga | 36 | EA | M-101 |
| 23 31 13 | Tee 24×12 to 18×12, 26 ga | 12 | EA | M-101 |
| 23 31 13 | Reducer 24×12 to 18×12, 26 ga | 8 | EA | M-101 |
| 23 31 16 | Acoustical duct liner 1" thick | 2,400 | SF | M-201 |
| 23 07 13 | Duct insulation 1-1/2" thick, external wrap | 4,800 | SF | M-201 |
| 23 33 13 | Volume damper 12×12, manual | 24 | EA | M-301 |
| 23 33 13 | Fire damper 16×12, 1-1/2 hr | 8 | EA | FP-101 |
| 23 05 48 | Trapeze hanger assembly, 24" duct | 210 | EA | M-101 |
Units of measure in sheet metal takeoff
Duct takeoff uses a mix of units because material is bought by weight, fabricated by length and installed by piece. Here is how we report each one.
| Item | Unit | How it's measured |
|---|---|---|
| Rectangular duct | LF / LB | Measured in LF by width × height, converted to LB using gauge and standard weight table |
| Spiral round duct | LF / LB | Measured in LF by diameter, converted to LB using gauge and spiral weight table |
| Rectangular fittings | EA | Counted by type, size and gauge; weight derived from fitting dimensions and gauge |
| Duct insulation | SF | Measured as surface area of duct, by thickness (1", 1-1/2", 2") |
| Acoustical liner | SF | Measured as internal surface area of duct, by thickness |
| Dampers | EA | Counted by type, size and actuator; fire and smoke dampers include sleeve |
| Hangers and supports | EA | Counted by type and spacing per SMACNA table for duct size |
| Flex duct | LF | Measured by diameter along the run shown on plan or schedule |
Worked example: takeoff of a small rectangular duct run
This example uses illustrative dimensions to show how we convert a duct run to pounds and count fittings. The actual project would have its own sizes and gauges.
Step 1 — Measure the run. From the mechanical plan, a supply trunk runs 50 ft at 24×12, then reduces to 18×12 for another 30 ft. Both segments are 26 ga galvanized.
Step 2 — Calculate surface area per linear foot. For rectangular duct, surface area = 2 × (width + height) / 12. For 24×12: 2 × (24+12)/12 = 6 SF per LF. For 18×12: 2 × (18+12)/12 = 5 SF per LF.
Step 3 — Convert to weight. 26 ga galvanized sheet weighs 0.906 lb per SF. Segment 1: 50 LF × 6 SF/LF = 300 SF; 300 × 0.906 = 271.8 lb. Segment 2: 30 LF × 5 SF/LF = 150 SF; 150 × 0.906 = 135.9 lb. Total duct weight = 407.7 lb.
Step 4 — Count fittings. The run has: 4 elbows (24×12), 2 elbows (18×12), 1 reducer (24×12 to 18×12), 2 tees (18×12), and 1 end cap (18×12). Each fitting is counted as EA.
Step 5 — Calculate fitting weight. Using standard fitting weight tables: 24×12 elbow ≈ 30 lb each; 18×12 elbow ≈ 22 lb each; reducer ≈ 25 lb; 18×12 tee ≈ 28 lb each; end cap ≈ 10 lb. Total fitting weight = (4×30) + (2×22) + 25 + (2×28) + 10 = 120 + 44 + 25 + 56 + 10 = 255 lb.
Step 6 — Add insulation. The spec calls for 1-1/2" external wrap on all supply duct. Insulation area = duct surface area = 300 + 150 = 450 SF. Add 10% for laps and waste: 450 × 1.10 = 495 SF.
Step 7 — Count hangers. Per SMACNA, 24×12 duct requires hangers at 6 ft on center; 18×12 at 6 ft on center. Segment 1: 50/6 = 8.33, round up to 9 hangers. Segment 2: 30/6 = 5 hangers. Total = 14 hangers.
Step 8 — Apply waste factor. Duct material waste is typically 10–15% for rectangular. We apply 12% to the total sheet metal weight: 407.7 + 255 = 662.7 lb; 662.7 × 1.12 = 742.2 lb. Waste is shown as a separate line.
Step 9 — Summarize. The takeoff lines would be: 50 LF 24×12 duct, 30 LF 18×12 duct, 4 EA 24×12 elbows, 2 EA 18×12 elbows, 1 EA reducer, 2 EA tees, 1 EA end cap, 495 SF insulation, 14 EA hangers, and 742.2 lb total sheet metal weight with waste. All dimensions are illustrative; your project will have different sizes and gauges.
What drives the hvac estimate for contractors
Relative impact on a typical estimate for this trade, based on estimator judgment. Select a bar for details.
Duct material
Galvanized steel is standard, but stainless steel and aluminum are specified for kitchens, laboratories and corrosive environments. Stainless weighs the same as galvanized but costs more and requires different fabrication methods. We note the material from the spec and schedule. For example, a kitchen exhaust duct may be 304 stainless steel at 18 ga, which changes the material cost and labor rate significantly compared to galvanized.
A 40" wide duct at 26 ga becomes 20 ga past the 60" threshold. The weight difference is large, and the transition point is often not marked on the plan. We read the gauge schedule and apply it by size. For example, a duct that starts at 48×24 and expands to 72×24 will have a gauge change at the 60" width; we split the run and apply the correct gauge to each segment, which affects both material weight and fabrication labor.
Seal class A requires mastic on all transverse and longitudinal joints. Class B is transverse only. Class C is transverse with tape. The mastic and labor line changes with the spec section, and the difference on a large job is significant. For instance, a 10,000 lb duct system with class A seal may require 50 gallons of mastic and 200 labor hours, while class C might require 10 gallons and 80 hours.
Ducts over 60" in either dimension require angle iron, Z-bar or tie rods per SMACNA. This steel is not duct weight but is part of the fabricated assembly. We add it as a separate line by size and length. For example, a 72×36 duct requires angle iron reinforcement at 5 ft on center, which adds 2.5 lb per foot of duct; on a 100 ft run, that is 250 lb of additional steel.
External wrap, ductboard and acoustical liner are measured separately. When both liner and wrap are specified on the same run, the material and labor are higher. We check the spec for both. For instance, a run with 1" liner and 2" external wrap requires two separate material lines and additional labor for the liner installation before the wrap is applied. The liner also adds weight to the duct, which affects hanger spacing.
SMACNA spacing varies by duct size — 8 ft for small duct, 4 ft for large. Using a single default spacing overcounts small duct and undercounts large duct. We apply the table to each run. For example, a 12" duct at 8 ft spacing over 100 ft requires 13 hangers, while a 48" duct at 4 ft spacing requires 26 hangers; using 6 ft for both would give 17 hangers, which is incorrect for both.
Where adopted, seismic bracing adds trapeze assemblies, rods, strut and anchors at spacing and at ends of runs. The jurisdiction decides whether this applies. We confirm the adopted code edition with the local building department. For example, in a seismic design category D area, a 100 ft run may require bracing at 20 ft on center plus at each end, adding 6 braced assemblies and associated hardware.
Galvanized steel is standard, but stainless steel and aluminum are specified for kitchens, laboratories and corrosive environments. Stainless weighs the same as galvanized but costs more and requires different fabrication methods. We note the material from the spec and schedule. For example, a kitchen exhaust duct may be 304 stainless steel at 18 ga, which changes the material cost and labor rate significantly compared to galvanized.
Common scope gaps we catch in the hvac bid estimating package
These are the items that most often fall between the plan and the schedule. We check each one against the drawings and specs.
- Gauge changes along a run are often not dimensioned on the plan. We read the gauge schedule and apply it by duct size, then note where the transition occurs. For example, a trunk duct that reduces from 48×24 to 36×18 may require a gauge change at the 60" width threshold; we split the run and apply the correct gauge to each segment.
- Reinforcement steel for large ducts is sometimes omitted from the duct schedule. We check duct dimensions against the SMACNA table and add angle, Z-bar or tie rods as a separate line. For instance, a 72×36 duct requires angle iron reinforcement at 5 ft on center, which adds 2.5 lb per foot of duct; on a 100 ft run, that is 250 lb of additional steel.
- Fire dampers at rated assemblies are shown on the life safety plan, not the mechanical plan. We cross-reference both and include the sleeve and access door. For example, a 2-hour rated shaft wall requires a fire damper with a sleeve and an access door for maintenance; we count all three items and reference the wall type.
- Roof curbs and roof jacks appear on the roof plan. We review the roof plan for exhaust and make-up air units and add them to the takeoff. For instance, a roof-mounted exhaust fan may require a 24×24 roof curb and a roof jack for the duct penetration; these are often not shown on the mechanical plan.
- Flex duct lengths are often shown on the schedule but not on the plan. We take the scheduled length and note the terminal connections. For example, a schedule may list 50 ft of 8" flex duct for a VAV box, but the plan may not show the routing; we include the length and note that the actual installed length may vary.
- Seismic restraints are required in some jurisdictions but not shown on the mechanical plan. We ask for the local amendment and add bracing where adopted. For instance, in a seismic design category D area, a 100 ft run may require bracing at 20 ft on center plus at each end, adding 6 braced assemblies and associated hardware.
- Test and balance taps and volume measuring stations are shown on the mechanical plan but not in the spec. We count them from the plan and note the sheet reference. For example, a plan may show a volume measuring station at each branch duct, but the spec may not list it; we include it in the takeoff and note the sheet and detail number.
- Duct sealant and mastic quantities are often not specified by volume. We calculate the linear feet of joint and apply the seal class to determine the gallons required. For instance, a 10,000 lb duct system with class A seal may require 50 gallons of mastic, while class C might require 10 gallons; we include the material and labor for application.
- Access doors for dampers and cleanouts are sometimes not shown on the plan. We check the spec for requirements and add access doors where needed. For example, a fire damper requires an access door for inspection and maintenance; we count the access door and note its location on the marked-up plan.
Duct materials and construction types
The material and construction type drive gauge availability, weight, fabrication labor and cost. This table compares common options.
| Material / construction | Typical use | Gauge range | Relative material cost index | Relative fabrication labor index |
|---|---|---|---|---|
| Galvanized G90 | Supply, return, exhaust | 26–16 ga | 1.0 | 1.0 |
| Galvanized G60 | General exhaust, less corrosive | 26–18 ga | 0.95 | 1.0 |
| Aluminized steel | High-temp exhaust, kitchen grease | 24–18 ga | 1.3 | 1.1 |
| Stainless 304 | Kitchen grease, laboratory exhaust | 20–16 ga | 3.5 | 1.8 |
| Stainless 316 | Corrosive fume exhaust | 20–16 ga | 4.2 | 2.0 |
| Black steel | Grease duct, welding required | 16–10 ga | 1.5 | 2.2 |
| Aluminum | Corrosive environments, lightweight | 24–18 ga | 1.8 | 1.3 |
| PVS-coated | Underground or corrosive | 24–18 ga | 2.0 | 1.4 |
| Ductboard | Return air plenum, low pressure | 1"–2" thick | 0.8 | 0.9 |
| Spiral round | Supply, return, exhaust | 26–20 ga | 1.1 | 1.2 |
| Flat oval | Space-constrained runs | 24–20 ga | 1.2 | 1.3 |
Codes, standards and spec sections that affect duct quantities
Ductwork quantities and cost are governed by model codes, SMACNA standards and project specifications. The International Mechanical Code (IMC) and International Residential Code (IRC) set requirements for duct construction, clearance and materials. The International Energy Conservation Code (IECC) drives insulation thickness and sealing. NFPA 90A governs air distribution systems in commercial buildings, including fire dampers and smoke detectors. NFPA 96 covers commercial kitchen grease duct. SMACNA HVAC Duct Construction Standards — Metal and Flexible is the fabrication reference: it dictates gauge by duct size and pressure class, reinforcement spacing, hanger spacing and seal class. The project spec section 23 31 00 will reference SMACNA and may add stricter requirements. For example, a spec may require seal class A on all supply duct, which increases mastic and labor. Seismic restraints are triggered by the adopted building code and local amendments; ASCE 7 and the IBC set the seismic design category, but the jurisdiction decides whether and how to enforce. Always confirm the adopted code editions and local amendments with the local building department. The duct schedule and spec sections 23 31 13 (metal ducts), 23 31 16 (duct accessories), 23 33 13 (dampers), 23 07 13 (duct insulation) and 23 05 48 (vibration isolation) give the specifics that we take off. We also cross-reference the life safety plan for fire and smoke damper locations, and the roof plan for curbs and roof jacks. If the spec calls for pressure class 2" w.g. or higher, we check the SMACNA reinforcement table for the required angle size and spacing, which adds steel weight and labor. Seal class A requires mastic on all transverse joints and longitudinal seams, while class B only requires transverse joints. That difference changes material takeoff and labor hours. We note the seal class on every run.
Who uses this HVAC takeoff for contractors
Mechanical contractors
You need a material breakdown to price a bid or check a supplier quote. The pounds and fitting counts feed directly into your fabrication and installation labor.
Sheet metal shops
You fabricate from the takeoff. Linear feet by size and gauge tells you how much sheet to order and how many fittings to build.
General contractors
You need a third-party number to compare subcontractor bids or to validate a change order. The marked-up plans show exactly what was measured.
HVAC subcontractors
You are bidding a package and need the duct portion separated from equipment and piping. This takeoff gives you Division 23 31 00 through 23 37 00.
Owners and developers
You want a budget check before committing to a mechanical contract. The takeoff shows the material quantities behind the number.