68 calculators in 10 categories.
Airflow and velocity
Find CFM and air speed from duct dimensions, load data, or field readings.
Duct Airflow and Velocity Checker Enter duct dimensions and CFM or air speed to solve for airflow, velocity, or capacity. Branch Airflow and Trunk Sizing Calculator Add branch airflows to find trunk flow and size sections at a chosen velocity. Room Supply Airflow from Sensible Load Use room sensible load and supply-to-room temperature difference to estimate required CFM. Duct Traverse Airflow Calculator Combine traverse readings with duct area and air properties to estimate average velocity and airflow. Duct Traverse Point Layout Calculator Enter duct dimensions and a supported traverse method to locate measurement points. Blower Table Airflow Calculator Use measured TESP and matching manufacturer blower-table points to estimate airflow for each entered tap.
Duct sizing and geometry
Choose duct dimensions and work out shape changes, offsets, and volume.
Duct Size Calculator Use airflow with a velocity or friction target to calculate round or rectangular duct dimensions. Duct Shape Converter Convert round, rectangular, and flat-oval dimensions using the selected area or friction basis. Rectangular Duct Transition Calculator Use opening dimensions, offsets, and a selected wall-angle limit to calculate required length or check transition angles. Flex Duct Installation Impact Calculator Use compression geometry or matched pressure tests to estimate installed flex-duct loss and pressure margin. Duct Volume Calculator Combine inside duct dimensions, segment length, and quantity to calculate cross-sectional area and internal volume. Two-Elbow Duct Offset Calculator Enter opposing elbow geometry and offset or straight gap to calculate connector cuts and developed length.
Ventilation and air balance
Check outdoor air, exhaust, makeup air, and return paths.
Room Airflow from ACH Calculator Enter room volume and an air-change target to calculate the corresponding airflow. Bathroom Exhaust Fan CFM Calculator Use bathroom floor area, fixture counts, and the selected HVI guideline mode to estimate intermittent exhaust CFM. Makeup Air Balance Calculator Compare exhaust and replacement airstreams to estimate makeup airflow on the selected mass or volume basis. Mixed Air Temperature and Outdoor Air Fraction Calculator Use entering air conditions and mixing proportions to find mixed-air temperature or outdoor-air fraction. Sensible Heat Recovery Calculator Enter airflows, temperatures, and recovery effectiveness to estimate sensible recovery and leaving conditions. CO₂ Ventilation Estimate Calculator Use documented CO₂ concentrations or decay readings to estimate ventilation under the selected mixing model. Single-Zone Ventilation Rate Calculator Apply entered people, floor area, ventilation rates, and distribution effectiveness to find zone outdoor airflow. Outdoor Air Load Calculator Compare outdoor-air states and flows with target conditions to calculate cooling, heating, and moisture duties. Return Air Pathway Calculator Apply documented path curves to transfer airflow and pressure limits to find capacity and required path counts. Whole-Dwelling Ventilation Calculator (2019 Method) Enter dwelling area, occupancy, and documented credits to calculate ventilation using the selected 2019 method. Multizone Ventilation Calculator Combine zone occupancy, primary flows, and entered ventilation factors to calculate system outdoor-air requirements. Outdoor Air Louver Performance Calculator Compare louver catalog data with airflow, opening, pressure, and weather limits to identify eligible candidates. Commercial Kitchen Hood Exhaust Calculator Check proposed exhaust, supply, and installation dimensions against the entered hood catalog requirements. VAV Terminal Airflow and Selection Calculator Compare zone loads, ventilation, and exact catalog points to check terminal flow, pressure, and capacity margins.
Duct component selection
Compare grilles, diffusers, dampers, and supports against entered limits.
Grille and Terminal Sizing Workbench Use airflow, opening dimensions, and free-area data to check grille size and velocity. Duct Leakage Check Workbench Use leakage measurements, airflow, or test pressure to compare leakage percentages and stated limits. Damper Actuator Torque Calculator Combine damper dimensions and documented torque factors to estimate actuator torque and selection margin. Diffuser Throw and Layout Calculator Combine room geometry and matched diffuser data to check outlet layout, throw, pressure, and catalog noise limits. Round Duct Gauge and Support Calculator Check round duct and support details against entered gauge, span, reaction, and hardware capacity requirements.
Pressure loss and static pressure
Add route losses and compare them with the available pressure budget.
Duct Total Effective Length Calculator Combine straight lengths and documented fitting allowances to total a duct route’s effective length. Available Static Pressure and Friction Budget Subtract component losses from available pressure and use route length to find the friction budget. Duct Pressure Drop Calculator Enter duct dimensions, airflow, and length to estimate friction and documented fitting pressure losses. Filter and Damper Pressure Drop Calculator Apply matched filter or damper data to airflow to estimate pressure drop and budget margin. Duct Static Regain Calculator Use upstream and downstream air speeds, density, and total-pressure loss to calculate net static pressure change. Total External Static Pressure (TESP) Calculator Combine supply and return static readings to find TESP and compare an entered equipment rating.
System estimation and checks
Compare duct paths, measured airflow balance, and sound power distribution.
Duct Path Pressure Calculator Enter route sections and losses to compare pressure requirements and identify the controlling path. Measured Airflow Balancing Workbench Compare measured terminal and system airflows with targets to find signed balancing differences. Duct Branch Sound Power Division Calculator Allocate an incident octave sound-power spectrum across outgoing duct areas and check energy recombination. Duct End Reflection Loss Calculator Use termination geometry and sound speed to estimate octave reflection loss and optional outgoing sound power.
Fans and energy
Compare fan operating points, drive settings, power, and running costs.
Fan Laws Calculator Change shaft speed or target actual airflow, with optional air-density correction, to estimate flow, pressure, and power at fixed diameter. Fan Power Calculator Use airflow, pressure, and efficiencies to estimate fan shaft power and electrical input. Fan Energy Cost Calculator Combine fan power, operating hours, and electricity rates to estimate energy use and cost. Fan Belt Drive and Pulley Calculator Enter motor speed and pulley diameters to calculate fan speed and compare drive changes. Fan and System Curve Calculator Intersect entered fan data with a system resistance model to estimate the operating airflow and pressure. Series and Parallel Fan Curve Calculator Combine matched fan curves in series or parallel and compare their resulting operating points. Fan Energy Index and Efficiency Grade Calculator Use matched test data and rating inputs to calculate fan energy index or efficiency grade and criterion margins. Fan Balance and Vibration Calculator Compare rotor balance or measured vibration with documented category limits to find tolerance margins. Fan Installation System Effect Calculator Apply documented inlet and outlet geometry to estimate system-effect pressure and supported airflow changes. Fan Tip Speed Calculator Use impeller diameter and shaft RPM to calculate tip speed, or solve for diameter or speed. Fan Heat Gain Calculator Combine shaft power, drive losses, motor location, and airflow to estimate airstream heat gain and temperature rise. Fan Static and Total Pressure Calculator Use signed fan-plane pressures, velocities, and densities to calculate fan static and total pressure rise.
Duct thermal and materials
Estimate heat transfer, condensation risk, material quantities, and movement.
Duct Heat Loss and Outlet Temperature Calculator Enter duct geometry, insulation, and air conditions to estimate heat transfer and outlet temperature. Duct Surface Area and Weight Calculator Use duct dimensions, lengths, and material properties to estimate sheet area and bare material weight. Duct Sealant Quantity Calculator Enter seam lengths and coverage data to estimate sealant volume and purchase quantity. Duct Wrap Roll Calculator Use bare duct dimensions, length, stretch-out, waste, and usable roll coverage to estimate wrap area and whole rolls. Duct Condensation and Insulation Calculator Use air moisture and duct surface or insulation data to check dew point, surface margin, and thickness. Duct Elbow Area Calculator Enter elbow dimensions, bend angle, and quantity to estimate rectangular panel area or round surface area. Duct Thermal Expansion Calculator Use installed length, wall temperatures, and a documented expansion coefficient to calculate duct movement.
Noise, installation and procurement
Compare duct sound levels, silencers, NC curves, and fan frequencies.
Duct Breakout Noise Calculator Use duct construction, octave sound power, and receiver geometry to estimate breakout contributions and budget margins. Duct Silencer Selection Calculator Compare silencer ratings with airflow, pressure, and octave sound budgets to rank eligible configurations. Noise Criteria (NC) Curve Calculator Compare a complete octave sound-pressure spectrum with NC curves to identify the rating and controlling bands. Fan Blade Pass Frequency Calculator Use blade count and fan RPM to calculate blade-pass harmonics, or solve for a target speed. Octave Band to dBA Calculator Combine compatible unweighted octave sound-pressure bands to estimate dBA and each band’s energy contribution.
Airflow measurement and conversion
Convert ACFM and SCFM, calculate air density, and apply pickup coefficients.
ACFM to SCFM Calculator Use actual and reference air conditions to convert ACFM and SCFM on a confirmed dry-air mass basis. Air Density Calculator Enter dry-bulb temperature, absolute pressure, and relative humidity to calculate moist-air density and specific volume. Airflow K-Factor Calculator Apply a documented pickup coefficient and pressure signal to calculate airflow, required signal, or apparent coefficient.