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HVAC Calculators
Use 107 professional tools for ventilation, ductwork, fans, loads, psychrometrics, hydronics, refrigeration service, energy, commissioning, and estimating. Connect airflow, duct, fan, load, psychrometric, hydronic, refrigeration, energy, commissioning, and estimate calculations using the same measured operating condition.
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Select a topic to reveal its calculators. Multiple topics can remain open at the same time.HVACUse 107 professional tools for ventilation, ductwork, fans, loads, psychrometrics, hydronics, refrigeration service, energy, commissioning, and estimating.107 available
Airflow, Ventilation & Exhaust
- Air Changes per Hour CalculatorCalculate room air changes from measured airflow and room dimensions in metric or imperial units.Open calculator
- Required Airflow CalculatorCalculate airflow for a visitor-entered ACH target and room dimensions.Open calculator
- Outdoor Air Ventilation CalculatorCombine visitor-entered per-person and per-area outdoor-air rates without embedding a jurisdictional table.Open calculator
- Supply Return Exhaust and Makeup Air Balance CalculatorReconcile separately measured supply, return, exhaust, makeup and relief airflow without double-counting outdoor air already included in supply.Open calculator
- Exhaust Fan Airflow CalculatorCalculate required exhaust airflow from room volume and a visitor-entered ACH or known process airflow.Open calculator
- Makeup Air Requirement CalculatorCalculate net makeup-air requirement after entered transfer and dedicated outdoor-air contributions.Open calculator
- Room Pressurization Airflow CalculatorCalculate net pressurizing airflow and entered leakage-area face velocity.Open calculator
- Airflow per Person CalculatorCalculate ventilation airflow per occupant or required airflow from an entered per-person design rate.Open calculator
- Airflow per Floor Area CalculatorCalculate airflow density or required airflow from an entered per-area rate.Open calculator
- ACFM and SCFM ConverterConvert actual and standard volumetric airflow using absolute pressure and absolute temperature.Open calculator
- Air Density CalculatorCalculate dry or moist-air density from dry-bulb temperature, absolute pressure and relative humidity.Open calculator
- Air Mass Flow CalculatorConvert volumetric airflow and entered/derived density into air mass flow.Open calculator
- Ventilation Heating and Cooling Load CalculatorCalculate sensible and latent ventilation load from dry-air mass flow and entered air-state differences.Open calculator
- Transfer Air Opening CalculatorCalculate required net free opening area from transfer airflow and target face velocity.Open calculator
Ductwork, Pressure & Balancing
- Duct Air Velocity CalculatorCalculate average duct velocity from airflow and round or rectangular dimensions.Open calculator
- Duct Size CalculatorSize a round duct or one rectangular dimension from airflow and target velocity.Open calculator
- Duct Geometry and Equivalent Diameter CalculatorCalculate area, wetted perimeter, hydraulic diameter and equal-friction equivalent round diameter for a rectangular duct.Open calculator
- Duct Friction Loss CalculatorCalculate straight-duct pressure loss with entered Darcy friction factor, density and hydraulic diameter.Open calculator
- Equal Friction Duct Sizing CalculatorSolve theoretical round diameter for an entered Darcy friction factor and pressure-loss rate.Open calculator
- Duct Friction Rate CalculatorConvert a measured or calculated pressure drop and length into common duct friction-rate units.Open calculator
- Total Effective Duct Length CalculatorAdd straight length and equivalent lengths for fittings and accessories.Open calculator
- Duct Fitting Pressure Loss CalculatorCalculate fitting pressure loss from entered loss coefficient and velocity pressure.Open calculator
- Air Static Dynamic and Total Pressure CalculatorResolve total, static and velocity pressure from any entered static pressure, density and velocity.Open calculator
- Velocity Pressure CalculatorConvert between air velocity and velocity pressure using entered density.Open calculator
- External Static Pressure Budget CalculatorCalculate remaining fan external-static allowance after entered component pressure drops.Open calculator
- Duct System Pressure Loss WorksheetTotal straight, fitting, filter, coil and terminal losses at one entered duty point.Open calculator
- Fan Operating Point CalculatorIntersect a simplified linear fan curve with a quadratic system curve for screening.Open calculator
- Fan Laws CalculatorScale fan airflow, pressure and power for a speed change on the same fan under similar conditions.Open calculator
- Fan Power and Efficiency CalculatorRelate airflow, pressure rise, air power, input power and total efficiency.Open calculator
- Filter and Coil Face Velocity CalculatorCalculate gross-face velocity and optional net-free-area velocity for filters or coils.Open calculator
- Grille and Register Airflow CalculatorRelate airflow, gross opening, entered free-area fraction and free-area velocity.Open calculator
- Branch Airflow Distribution CalculatorDistribute a total airflow across three branches in proportion to entered design weights.Open calculator
- Proportional Air Balancing CalculatorCalculate proportional damper corrections and each terminal's share of design airflow.Open calculator
- Airflow Traverse CalculatorAverage up to six equally weighted, equal-area velocity readings and calculate duct airflow from the entered traverse area.Open calculator
- Duct Leakage CalculatorCalculate leakage flow, leakage percentage and normalized leakage from test results.Open calculator
Heating, Cooling Loads & Equipment
- Envelope Heat Loss WorksheetEstimate steady envelope transmission through three entered assemblies without claiming a full design load.Open calculator
- Outdoor Air Heating Load CalculatorCalculate sensible heating or cooling load from an entered outdoor airflow and temperature difference.Open calculator
- Internal Heat Gain WorksheetCombine occupant sensible/latent gains, lighting and equipment with entered use factors.Open calculator
- Solar Window Heat Gain WorksheetEstimate transmitted solar gain from entered glazing area, irradiance, SHGC and shading factor.Open calculator
- Room and Block Load SummaryCombine room sensible and latent loads and apply separate block diversity factors.Open calculator
- HVAC Airflow and Supply Temperature CalculatorSolve airflow or supply-air temperature from a sensible load, room temperature and entered air density.Open calculator
- Furnace Temperature Rise CalculatorCalculate delivered sensible capacity or air temperature rise across a furnace.Open calculator
- Equipment Capacity to Load ComparisonCompare entered sensible, latent and total equipment capacities against calculated design loads.Open calculator
- Heat Pump Balance Point CalculatorEstimate the outdoor temperature where constant entered heat-pump capacity equals a linear building heat-loss line.Open calculator
- Supplemental Heat Requirement CalculatorCalculate supplemental heating needed after entered heat-pump capacity and other available heat.Open calculator
- HVAC Capacity Unit ConverterConvert HVAC capacity among kW, Btu/h, refrigeration tons and kcal/h.Open calculator
Psychrometrics, Humidity & Coils
- Psychrometric Air Properties CalculatorCalculate humidity ratio, dew/frost point, enthalpy, specific volume and moist-air density from dry bulb, RH and pressure.Open calculator
- Dew Point CalculatorEstimate water dew point or subfreezing frost point from dry-bulb temperature and relative humidity using Buck water/ice saturation relations.Open calculator
- Wet Bulb Temperature CalculatorEstimate near-surface psychrometric wet-bulb temperature from dry bulb and RH with the pressure-independent Stull empirical approximation.Open calculator
- Humidity Ratio CalculatorCalculate humidity ratio from dry bulb, RH and pressure, or RH from dry bulb and humidity ratio.Open calculator
- Moist Air Enthalpy CalculatorCalculate moist-air enthalpy or dry-bulb temperature from humidity ratio on a dry-air basis.Open calculator
- Specific Volume and Moist Air Density CalculatorCalculate moist-air specific volume per kg dry air and density per m³ from temperature, humidity ratio and pressure.Open calculator
- Mixed Air CalculatorMix two air streams algebraically on a dry-air mass basis using entered temperatures, humidity ratios and flow shares.Open calculator
- Outdoor Air Fraction CalculatorEstimate outdoor-air fraction from a conserved tracer such as dry-bulb temperature or humidity ratio.Open calculator
- Sensible Heat Ratio CalculatorCalculate sensible heat ratio and sensible/latent split from entered loads.Open calculator
- Air Coil Capacity CalculatorCalculate signed sensible, latent and total air-side coil duty from dry-air mass flow and entering/leaving states.Open calculator
- Condensate Production CalculatorCalculate condensate production from dry-air mass flow and humidity-ratio reduction.Open calculator
- Humidity Control Load CalculatorCalculate humidification or dehumidification moisture rate and latent load from dry-air flow and humidity-ratio change.Open calculator
- Evaporative Cooling Effectiveness CalculatorCalculate direct-evaporative effectiveness or predicted leaving dry bulb from entering dry and wet bulb.Open calculator
- Heat Recovery Effectiveness CalculatorCalculate sensible temperature effectiveness or enthalpy effectiveness of an air-to-air recovery device.Open calculator
- Coil Bypass Factor CalculatorCalculate cooling-coil bypass factor and contact factor from entering, leaving and apparatus dew-point temperatures.Open calculator
Hydronics
- Hydronic Heat and Flow CalculatorRelate hydronic heat transfer, volumetric flow and temperature difference using visitor-entered fluid properties.Open calculator
- Hydronic Pipe Velocity CalculatorCalculate pipe velocity from fluid flow and actual inside diameter.Open calculator
- Hydronic Pipe Pressure Loss CalculatorCalculate straight-pipe hydronic pressure loss with entered Darcy factor, density, length, diameter and flow.Open calculator
- Multi Section Hydronic Pressure Loss WorksheetTotal entered pressure losses and design flows for three hydronic circuit sections.Open calculator
- Hydronic Fitting and Valve Pressure Loss CalculatorCalculate local hydronic loss from combined K coefficients and pipe velocity.Open calculator
- Hydronic Pump Head Requirement CalculatorCombine circuit pressure loss and signed static elevation into net system head, then report nonnegative required pump head.Open calculator
- Hydronic Pump Power CalculatorCalculate hydraulic and input power from flow, head, density and pump efficiency.Open calculator
- Hydronic Pump Duty Point CalculatorCompare a candidate pump point with the system head required at that same flow, and report the separate design-flow duty.Open calculator
- Hydronic Expansion Tank CalculatorEstimate minimum tank volume from expanded fluid volume and absolute pressures, assuming tank gas precharge is equalized to the entered minimum system pressure.Open calculator
- Hydronic System Water Volume EstimatorEstimate contained fluid volume from three pipe runs plus entered equipment volume.Open calculator
- Buffer Tank Sizing CalculatorEstimate additional buffer volume required to meet a minimum equipment run time after accounting for concurrent system load.Open calculator
- Boiler Cycling and Runtime CalculatorEstimate minimum-output cycling duty, hourly runtime and cycles only while load is below minimum modulation output.Open calculator
- Primary Secondary Flow Mixing CalculatorCalculate mixed temperature from two hydronic streams or solve the required primary-flow fraction.Open calculator
- Radiator Output Correction CalculatorCorrect a radiator's positive rated output for a different mean-water-to-room temperature difference.Open calculator
- Underfloor Heating Loop WorksheetEstimate tube length, loop count and hydronic flow from area, spacing, allowance, loop limit and design load.Open calculator
Refrigeration & Service
- Refrigerant Superheat CalculatorCalculate superheat and compare it with an optional manufacturer target using evaporating dew-point saturation temperature for zeotropic refrigerants.Open calculator
- Refrigerant Subcooling CalculatorCalculate liquid subcooling and compare it with an optional manufacturer target using condensing bubble-point saturation temperature for zeotropic refrigerants.Open calculator
- Evaporator Approach Temperature CalculatorCalculate evaporator approach between leaving air and entered evaporating saturation temperature.Open calculator
- Condenser Approach Temperature CalculatorCalculate condenser approach between entered condensing saturation and entering outdoor/secondary-fluid temperature.Open calculator
- Air Conditioner Temperature Split CalculatorCalculate signed return-to-supply dry-bulb split and compare it with an optional expected range.Open calculator
- Refrigeration Compression Ratio CalculatorCalculate absolute compression ratio from suction and discharge gauge pressures plus local atmospheric pressure.Open calculator
- Refrigerant Line Temperature Drop CalculatorCalculate signed line temperature change per length and total change between two points.Open calculator
- Refrigerant Charge Adjustment WorksheetTrack weighed additions and removals against an entered starting charge and optional target.Open calculator
- Evacuation Decay Test TrackerCalculate vacuum rise rate and pass/fail against a visitor-entered final-pressure limit.Open calculator
- Refrigerant Leak Rate CalculatorCalculate average mass-loss rate and annualized percentage from weighed refrigerant loss over time.Open calculator
- Recovery Cylinder Fill CheckerCheck weighed cylinder contents against a visitor-entered allowable liquid fill fraction and refrigerant liquid density.Open calculator
- Refrigerant Recovery Time TrackerEstimate remaining recovery time from starting mass, recovered mass, elapsed time and a constant recent rate.Open calculator
- Compressor Runtime and Cycling CalculatorCalculate runtime fraction, cycles per hour and average on/off durations from observation data.Open calculator
- Compressor Capacity Comparison WorksheetCompare measured refrigeration capacity and power with rated values at the same stated condition.Open calculator
Energy, Commissioning & Estimating
- HVAC Efficiency CalculatorCalculate COP and EER from delivered capacity and electrical input.Open calculator
- HVAC Energy and Cost CalculatorEstimate electrical energy and cost from input power, runtime and visitor-entered tariff.Open calculator
- Existing and Proposed HVAC Cost ComparisonCompare annual energy, operating cost, savings and simple payback for existing and proposed equipment.Open calculator
- Heat Pump and Resistance Heating ComparisonCompare input energy and cost for the same delivered heat using an entered heat-pump COP.Open calculator
- Heat Pump and Furnace Cost ComparisonCompare cost per delivered kWh for a heat pump and fuel furnace using entered COP, efficiency and fuel energy content.Open calculator
- Degree Day Energy EstimateEstimate weather-normalized heating or cooling energy from entered degree days and building loss/gain coefficient.Open calculator
- Runtime from Energy Bill CalculatorEstimate equivalent full-load runtime from metered energy and entered equipment input.Open calculator
- Specific Fan Power CalculatorCalculate fan input power per unit airflow in SI and common imperial form.Open calculator
- Filter Pressure Drop Energy Cost CalculatorEstimate fan energy and cost attributable to an entered filter pressure drop.Open calculator
- Economizer Savings Scenario CalculatorEstimate total air-side cooling avoided when outdoor enthalpy is below return enthalpy for an entered dry-air flow and hours.Open calculator
- Heat Recovery Savings CalculatorEstimate thermal energy recovered and equivalent input energy avoided from airflow, state difference, effectiveness and hours.Open calculator
- Duct Heat and Insulation CalculatorEstimate steady one-dimensional duct heat transfer and compare two entered overall U-values.Open calculator
- HVAC Material Takeoff CalculatorApply a visitor-entered allowance to net duct length, pipe length and insulation area without inventing packaging increments.Open calculator
- Sheet Metal Surface Area CalculatorCalculate sheet area for a straight round or rectangular duct section plus entered seam/waste allowance.Open calculator
- Duct Weight CalculatorEstimate straight duct metal mass from sheet area, thickness and visitor-entered material density.Open calculator
- Condensate Drain Slope CalculatorCalculate required fall, slope percentage and grade ratio for a condensate drain run.Open calculator
- Condensate Pump Capacity CalculatorCompare candidate pump capacity with peak condensate production and an entered design factor of at least 100%.Open calculator