HVAC Engineering Calculators Directory
Browser-based HVAC calculation tools for airflow, cooling loads, heating systems, building science, psychrometrics, and field diagnostics. Client-side computation with local in-browser processing.
All 25 Engineering Tools
Filter by domain or search for specific parameters (CFM, BTU, sensible heat, static pressure, A2L glide):
Digital Ductulator & Air Duct Sizing Tool
Free online ductulator for HVAC duct sizing. Size round and rectangular air ducts via equal friction and Huebscher's formula. Real-time 2D visualizer.
Flexible Duct CFM & Friction Drop Chart
Flexible duct CFM chart for 4-in to 20-in ducts. Compare airflow across 0.05–0.15 in. wg friction with modeled 0%–30% sag deratings from ASHRAE RP-1333 data.
HVAC CFM & Airflow Calculator
Calculate HVAC airflow (CFM) from duct size, velocity (FPM), sensible load (1.08 × ΔT), room ACH, or tonnage benchmarks. Runs locally in your browser.
Kitchen Range Hood CFM & Make-Up Air Sizer
Size kitchen range hood CFM for gas and electric cooktops using HVI width guidance. Evaluate make-up-air requirements under applicable IRC provisions.
Duct Friction Loss & Total Equivalent Length (TEL) Sizer
Calculate duct friction loss rate using Darcy-Weisbach and Colebrook models. Evaluate Available Static Pressure (ASP) and design friction rate concepts.
Equivalent Length & Total Effective Length (TEL) Calculator
Calculate duct Total Effective Length (TEL) and fitting equivalent lengths referencing ACCA Manual D methodology to determine design friction rates.
MERV Air Filter Sizing & Static Pressure Drop Sizer
Calculate HVAC air filter face velocity (FPM) and static pressure drops across 1-inch, 2-inch, and 4-inch deep MERV 8 to MERV 16 pleated media.
BTU Heating & Cooling Load Calculator
Estimate whole-home and room heating and cooling loads (BTU/hr and Tons) based on square footage, climate zone, insulation quality, and window exposure.
AC Tonnage & Room Capacity Calculator
Estimate residential AC cooling capacity (1.5 to 5.0 Tons) and SEER2 operating costs using regional climate factors and ceiling height adjustments.
HVAC Model Number Tonnage Decoder
Decode supported manufacturer model-number patterns (Carrier, Trane, Lennox, Goodman, Rheem, Daikin) to identify nominal tonnage, BTU capacity, and series.
Mini-Split Multi-Zone Sizing Calculator
Estimate multi-zone ductless mini-split sizing. Match room screening loads to candidate indoor heads (6k to 24k BTU) and supported outdoor unit configurations.
Target Superheat & Subcooling Charging Calculator
Calculate target superheat (fixed orifice) and target subcooling (TXV) across R-454B, R-32, R-410A, and R-22 with field diagnostic guidance.
Digital Refrigerant Pressure-Temperature Chart
Interactive refrigerant Pressure-Temperature (PT) chart for R-454B, R-32, R-410A, R-22, and zeotropic blends. Instant bubble and dew point saturation lookups.
Psychrometric Chart & Moist Air Calculator
Calculate moist air thermodynamic properties from supported input pairs (DB+RH, DB+WB, DB+DP) with barometric altitude adjustment.
Refrigerant Line Set Charge & Weigh-In Calculator
Calculate OEM-specified line-set refrigerant charge adjustments and weigh-in targets for R-454B, R-32, and R-410A using verified manufacturer data.
Heat Pump Sizing & Balance Point Tool
Calculate heat pump thermal balance point, cold-climate heating capacities (47°F, 17°F, 5°F), aux heat strip sizing (kW), and dual-fuel economic crossover.
Furnace Sizing & AFUE Efficiency Calculator
Estimate residential furnace sizing, heating BTU requirements, and AFUE efficiency (80% vs 96% condensing) based on home area, climate zone, and envelope.
Hydronic Boiler & Baseboard Sizing Calculator
Calculate hydronic boiler sizing, required DOE heating capacity, fin-tube baseboard BTU/ft, radiator EDR, and I=B=R piping/pickup factors.
ASHRAE Hydronic Expansion Tank Sizing Calculator
Size closed-loop diaphragm and bladder expansion tanks using ASHRAE technical references with optional commercial vessel rating considerations.
Garage & Workshop Heater Sizing Calculator
Size gas unit heaters, electric heaters, and radiant tubes for 1 to 3-car garages. ACCA Manual J and ASHRAE heat loss with slab insulation derating.
Combustion Air & Confined Space Sizer (NFPA 54 / IFGC)
Evaluate mechanical room combustion air openings under NFPA 54 and IFGC reference methods, including standard 50 cu ft/1,000 BTU confined space checks.
Thermal Bridging & Effective R-Value Calculator
Estimate whole-wall effective R-value and assembly U-factor accounting for framing thermal bridging referencing ASHRAE 90.1 Appendix A and IECC.
Insulation R-Value & U-Factor Calculator
Build multi-layer wall, roof, and floor assemblies to calculate 1-D series R-value (R_stack) and overall U-factor with selected IECC reference benchmarks.
Building Heat Loss & Infiltration Calculator
Estimate whole-building peak heat loss combining envelope conductive transmission (U * A * Delta T), slab perimeter F-factors, and air infiltration leakage.
Heat Pump Auxiliary Electric Heat Strip Sizing Calculator
Estimate heat pump auxiliary electric heat strip deficit (kW), emergency backup sizing, NEC Article 424 circuit ampacity guidelines, and temperature rise.
Engineering References & Physics
Built on First Principles & Engineering References
Calculators in this directory reference recognized engineering methodologies and fluid mechanics principles:
Airflow & Hydraulics
Calculates duct sizing and friction losses referencing Colebrook-White equations, Darcy-Weisbach relations, SMACNA guidelines, and Manual D design concepts.
Read Airflow Pillar Guide →Cooling & Thermal Loads
Provides cooling load estimates and equipment sizing comparisons referencing ACCA Manual J/S principles and published AHRI performance data.
Read Cooling Pillar Guide →Heating & Electrification
Models heat pump balance points, temperature-dependent capacity curves, combustion air sizing references (NFPA 54/IFGC), and hydronic heating estimates.
Read Heating Pillar Guide →Diagnostics & Refrigerants
References thermophysical property data (including NIST REFPROP models), zeotropic A2L temperature glide concepts, and field superheat/subcooling measurement conventions.
Read Diagnostics Pillar Guide →Client-Side Calculation Architecture
Unlike cloud-hosted calculation platforms, all 25 HVACLogic calculators evaluate formulas directly in your browser. Inputs and project figures remain on your local device without being stored in an external database. Standard anonymous site analytics are collected for performance and traffic measurement.