How do I calculate duct surface area for material and sealant?

For rectangular duct, perimeter times length gives square feet: a 24 by 12 inch duct has a 6-foot perimeter, so 10 linear feet is 60 square feet of metal. The Duct Surface Area calculator handles rectangular, round, and fittings, then feeds Sealant Usage and Insulation Cost so those quantities scale automatically. Round duct uses pi times diameter times length, which usually beats a rectangular equivalent on both metal weight and pressure drop.

How do I size a fan motor for an air handler?

Brake horsepower is CFM times total static pressure divided by 6,356 times fan efficiency. The Fan Motor Sizing calculator runs that math, so 10,000 CFM at 2.5 inches w.g. and 65 percent efficiency needs about 6 BHP, and you round up to the next standard motor. Remember to include Filter Rack Pressure Drop and coil and damper losses in total static, because sizing on duct loss alone leaves the fan short at design airflow.

What leakage rate passes a SMACNA duct leakage test?

SMACNA rates leakage by class as CFM lost per 100 square feet of duct surface at a test pressure. The Leakage Test Rate calculator takes your measured leakage and duct area and returns CFM/100 square feet so you can compare against the specified class, commonly Leakage Class 3 or 6 for sealed low-pressure systems. Failing runs drive Rework Cost, so catching a seam or Flange Count problem before test saves relabeling and reseal time.

How much coil stock do I actually get out of a sheet?

Nesting and drops decide it. The Panel Cut Yield and Duct Sheet Yield calculators divide usable part area by the blank or coil area to give a yield percentage, and a well-nested rectangular duct shop often lands around 80 to 90 percent. That yield number flows straight into Cost Per Unit, so a 10-point yield swing on 22-gauge galvanized can move a bid more than the labor line does.

How do I size condensate drainage for a cooling coil?

Condensate rate follows the latent load: roughly 1 to 1.5 gallons per hour per 10,000 CFM in humid conditions, though it scales with entering wet-bulb. The Coil Drain Rate calculator estimates gallons per hour from airflow and conditions so you can size the drain pan connection and trap. Undersizing here causes pan overflow and callbacks, and it ties back to Air Handler Coil Capacity since higher tonnage means more moisture to carry away.

How do I price a duct or equipment job with a target margin?

Roll material and labor into a unit cost, then apply margin. Cost Per Unit gathers metal from Duct Sheet Yield, Sealant Usage, Insulation Cost, and Assembly Labor, and the Quote Price calculator marks that up to your target. Because Labor Utilization and Shop Throughput tell you whether the floor can actually deliver at that price, you avoid winning a bid you cannot build on time, which is where reseal and Rework Cost quietly erase the margin.

Manufacturing calculator category

HVAC Ductwork, Air Handling & Mechanical Products calculators

This category covers the fabrication and estimating math for rectangular and round ductwork, fittings, air handlers, dampers, and VAV boxes. It is built for sheet metal shops, air handling equipment builders, and mechanical product estimators who need yield, sizing, leakage, and cost numbers to price jobs and load the shop.

What this hub covers

Calculators for sheet metal duct shops and air handler builders: duct sheet yield, surface area, fan motor sizing, leakage test rates, insulation cost, and pricing.
Browse hvac ductwork, air handling & mechanical products calculators for manufacturing planning, quoting, quality, capacity, and operations decisions.

Best calculators in this category

Duct Sheet Yield: Calculate the sheet metal yield rate for duct fabrication. Compare accepted duct sections or blanks against total sheet metal processed to find your current yield and the gap to your shop target.
Air Handler Coil Capacity: Estimate how many chilled water or DX coil assemblies your air handler production line can complete per shift. Accounts for coils per setup, available setups, line uptime, and first-pass assembly yield.
Fan Motor Sizing: Estimate the required fan motor shaft power or brake horsepower from design airflow, total static pressure, fan efficiency, and a motor service factor. Use for supply, return, and exhaust fan selection in air handling units and ductwork systems.
Filter Rack Pressure Drop: Estimate total filter rack pressure drop by applying a loading factor to initial clean resistance and scaling for actual versus design airflow. Use for AHU fan selection, energy calculations, and filter replacement scheduling.
Sealant Usage: Estimate the quantity of duct sealant or mastic needed for a ductwork installation. Enter the total length of duct joints and seams, the sealant coverage rate per linear foot, and your application efficiency to get the order quantity.
Assembly Labor: Estimate total assembly labor cost for ductwork fabrication or air handling unit assembly. Enter the number of duct sections or AHU assemblies, labor hours per unit, loaded labor rate, and a fixed setup or staging cost to get total and per-unit labor cost.
Leakage Test Rate: Calculate the duct leakage test pass rate for fabricated or installed ductwork sections. Compare the number of sections that pass pressurization testing to the total tested, and check the gap against your acceptance target.
Insulation Cost: Estimate total duct insulation cost by combining surface area, insulation material and labor rate per square foot, a waste and overlap allowance, and fixed mobilization or material delivery cost.
Shop Throughput: Calculate actual ductwork fabrication shop throughput in duct sections per hour or pounds of sheet metal processed per hour. Divide completed output by runtime and apply a realistic shop efficiency to get the honest production rate for scheduling and quoting.
Cost Per Unit: Estimate cost per duct section, fitting, or air handling unit. Combine material cost per unit, fabrication labor rate, an overhead and burden factor, and fixed project costs to calculate a total and a per-unit cost for quoting and job cost comparison.
Duct Surface Area: Calculate total surface area of rectangular duct sections for insulation coverage, sheet metal buy quantity, sealant planning, and coating estimates. Enter duct width, duct height, section length, and the number of sections to get total square footage.
Flange Count: Estimate total duct flange and connection production output per shift. Combine flanges per setup, available setups per shift, TDC or TDF roll-forming line uptime, and first-pass yield to plan flange inventory and assembly scheduling.

Common manufacturing problems solved

HVAC ductwork
air handling
duct fabrication
sheet metal
fan motor sizing
filter pressure drop
duct surface area
sealant usage
insulation cost
leakage test

Live market signals for this industry

Industrial electricity averages 8.71 cents per kWh across the U.S. (EIA, May 2026), up 5.1% from a year earlier. Energy-intensive steps carry this directly into unit cost.
U.S. housing starts run at 1,427k per year (Census, Jun 2026), up 3.5% from a year earlier, the demand driver for building products.

Category questions

How do I calculate duct surface area for material and sealant? For rectangular duct, perimeter times length gives square feet: a 24 by 12 inch duct has a 6-foot perimeter, so 10 linear feet is 60 square feet of metal. The Duct Surface Area calculator handles rectangular, round, and fittings, then feeds Sealant Usage and Insulation Cost so those quantities scale automatically. Round duct uses pi times diameter times length, which usually beats a rectangular equivalent on both metal weight and pressure drop.
How do I size a fan motor for an air handler? Brake horsepower is CFM times total static pressure divided by 6,356 times fan efficiency. The Fan Motor Sizing calculator runs that math, so 10,000 CFM at 2.5 inches w.g. and 65 percent efficiency needs about 6 BHP, and you round up to the next standard motor. Remember to include Filter Rack Pressure Drop and coil and damper losses in total static, because sizing on duct loss alone leaves the fan short at design airflow.
What leakage rate passes a SMACNA duct leakage test? SMACNA rates leakage by class as CFM lost per 100 square feet of duct surface at a test pressure. The Leakage Test Rate calculator takes your measured leakage and duct area and returns CFM/100 square feet so you can compare against the specified class, commonly Leakage Class 3 or 6 for sealed low-pressure systems. Failing runs drive Rework Cost, so catching a seam or Flange Count problem before test saves relabeling and reseal time.
How much coil stock do I actually get out of a sheet? Nesting and drops decide it. The Panel Cut Yield and Duct Sheet Yield calculators divide usable part area by the blank or coil area to give a yield percentage, and a well-nested rectangular duct shop often lands around 80 to 90 percent. That yield number flows straight into Cost Per Unit, so a 10-point yield swing on 22-gauge galvanized can move a bid more than the labor line does.
How do I size condensate drainage for a cooling coil? Condensate rate follows the latent load: roughly 1 to 1.5 gallons per hour per 10,000 CFM in humid conditions, though it scales with entering wet-bulb. The Coil Drain Rate calculator estimates gallons per hour from airflow and conditions so you can size the drain pan connection and trap. Undersizing here causes pan overflow and callbacks, and it ties back to Air Handler Coil Capacity since higher tonnage means more moisture to carry away.

Last reviewed 2026-05-12.