HVAC Calculators
14 specialized calculators for HVAC operations. BTU, CFM, tonnage, ducts, SEER, refrigerant. Every calculator runs deterministic formulas on the edge — no page reloads, no signup, no guesswork.
Available HVAC Calculators
BTU to CFM Airflow Calculator
Convert sensible heating and cooling BTU/hr to required CFM airflow and tonnage for HVAC design.
CFM to BTU/hr Capacity Calculator
Convert airflow CFM and temperature split to sensible thermal BTU/hr output for HVAC equipment.
Refrigerant Pressure-Temperature (P-T) & Superheat Calculator
Diagnose refrigerant saturation temperatures, subcooling, and superheat for heat pumps and AC units.
HVAC Duct Sizing & Air Velocity Calculator
Size round and rectangular supply and return ducts based on CFM and friction rate.
Humidity, Dew Point & Comfort Calculator
Calculate dew point temperature, grains of moisture, and indoor comfort index.
Residential & Commercial Heat Load (Manual J) Tonnage Calculator
Estimate residential cooling and heating heat loss/gain in BTU/hr and required HVAC air conditioning tonnage.
Sensible Heat Ratio (SHR) & Enthalpy Airflow Calculator
Calculate Sensible Heat Ratio (SHR) from sensible and latent heat loads to design coils and dehumidification performance.
Total External Static Pressure (TESP) & Blower Fan Drop Calculator
Measure air handler blower performance by calculating Total External Static Pressure (TESP) across return and supply plenums.
Electric Heat Strip kW to BTU/hr & Amp Draw Calculator
Convert electric heat strip kilowatt (kW) ratings into thermal heating BTU/hr output and electrical breaker ampacity.
SEER2 vs SEER Energy Efficiency Cost Savings Calculator
Calculate annual electricity utility bill savings and 10-year lifetime ROI when upgrading to higher efficiency SEER2 heat pumps and air conditioners.
Chilled Water Flow Rate GPM & Hydronic Tonnage Calculator
Calculate required hydronic flow rate in Gallons Per Minute (GPM) for commercial chilled water loops and cooling towers.
Refrigerant Line Set Copper Tubing Diameter & Velocity Calculator
Size suction and liquid line copper tubing diameters for R-410A and R-32 systems based on equivalent length and capacity.
SEER2 to SEER HVAC Efficiency Rating Converter
Convert AHRI 210/240-2023 SEER2 ratings to legacy SEER equivalents, accounting for increased static pressure testing (0.50 in. w.g. vs 0.10 in. w.g.), and calculate annual operating costs.
Psychrometric Sensible Heat Ratio (SHR) & Dehumidification Calculator
Calculate sensible cooling capacity, latent cooling capacity, sensible heat ratio (SHR), and moisture removal rate (lbs/hr) across air handler cooling coils.
HVAC Engineering & Technical Comparisons
All comparisons →Thermal energy transfer rate versus volumetric airflow velocity in HVAC sizing
Total cubic feet per minute moved versus linear velocity in feet per minute
Insulation resistance to heat flow versus whole-assembly conductive heat transfer coefficient
Refrigeration tonnage versus British Thermal Units per hour in cooling equipment
A1 high-GWP refrigerant blend versus A2L single-component low-GWP fluid in modern HVAC cycles
Percentage vapor saturation index versus the invariant thermal condensation threshold in psychrometric calculations
Legacy AHRI cooling efficiency versus DOE 2023 Appendix M1 external static pressure rating
Thermodynamic vapor-compression heat transfer versus fossil fuel chemical combustion
Variable-frequency BLDC motor modulation versus single-stage on/off contactor cycling
Temperature differential thermal energy versus moisture vaporization enthalpy
Why use CalcSite for hvac math?
Each hvac calculator on this page documents its formula openly, shows the inputs it uses, and computes results server-side on Cloudflare's edge network. That means identical inputs always produce identical outputs — the same guarantee a spreadsheet gives you, without building one. The hvac tools above were built from recurring search demand, so they model the questions professionals in this vertical actually ask, and every result includes the intermediate numbers behind the final figure.
Need something outside this vertical? The full catalog covers all registered calculators, or browse the niche hubs from the homepage taxonomy.
HVAC calculator FAQ
Are these hvac calculators free to use?
Yes. Every calculator on this page is free, requires no account, and has no usage quota.
How accurate are the results?
Each tool runs a deterministic formula documented on its own page, so you can verify every step of the calculation instead of trusting a black box.
Do the calculators work on mobile?
Yes. Calculations execute on the edge server and stream back instantly, so they work the same on phones, tablets, and desktops without installing anything.