BUILDING ENGINEERING CALCULATORS
Free building-services sizing tools
Soft Études provides practical preliminary sizing calculators. 92 technically reviewed building-services, energy, electrical, mechanical and workshop tools are now available in English.
Hydraulic separator and heating manifold
Preliminary sizing of a hydraulic separator, heating manifold, primary and secondary flow rates, pipe connections and main dimensions.
Open calculatorExpansion vessel for heating and chilled water
Estimate the minimum expansion vessel capacity, expansion volume, operating pressures and a standard vessel size.
Open calculatorHeating water flow rate and pipe diameter
Calculate heating water flow rate, theoretical diameter, suggested pipe size and actual velocity.
Open calculatorCircular and rectangular duct sizing
Calculate a circular duct diameter, an equivalent rectangular size and an indicative insulation surface.
Open calculatorAirflow in circular and rectangular ducts
Calculate airflow from duct dimensions and air velocity, and compare circular and rectangular sections.
Open calculatorAir duct pressure loss
Calculate pressure losses by duct section, including linear, fixed and fitting losses.
Open calculatorCirculator selection and operating point
Calculate system flow rate and head, assess a control valve and check the operating point against a manufacturer pump curve.
Open calculatorPlate heat exchanger for heating and cooling
Preliminary plate heat-exchanger sizing with primary and secondary flow rates, LMTD, approach temperature, indicative area and connections.
Open calculatorDirect boiler heating circuit
Preliminary sizing of a boiler supplying one direct heating circuit without a hydraulic separator or manifold.
Open calculatorBoiler cascade preliminary sizing
Check installed output, N+1 redundancy, modulation range, primary flow and a generic component list for a boiler cascade.
Open calculatorHydraulic separation for heat pumps and hybrid systems
Compare primary and secondary flow rates, manufacturer minimum flow, buffer volume and indicative separator arrangements.
Open calculatorWater flow rate and AHU coil duty
Calculate water flow from heating or cooling duty, or sensible air-coil duty from airflow and supply-air temperature difference.
Open calculatorLocal pressure loss using K coefficient
Calculate local pressure loss through a bend, tee, valve or fitting from its K coefficient, flow rate and internal diameter.
Open calculatorHeat loss from circular pipes
Calculate linear heat loss, surface temperature, dew point, condensation or burn risk and indicative annual energy loss.
Open calculatorAHU airflow preliminary sizing
Estimate AHU airflow from air-change rate, occupancy, outdoor-air requirement or sensible cooling duty.
Open calculatorAirside free-cooling potential
Estimate sensible cooling available from outdoor air and compare it with the room sensible load.
Open calculatorMoist-air psychrometrics
Calculate dew point, humidity ratio, absolute humidity, enthalpy, air density and condensation or frost risk.
Open calculatorHeating and cooling load estimate
Simplified heating and cooling load estimate using overall heat-loss coefficient, exposed area and ventilation.
Open calculatorCold-room cooling load
Preliminary cold-room duty from envelope, air change, doors, lighting, people, products and evaporator fans.
Open calculatorRefrigeration COP
Compare actual refrigeration COP with an ideal Carnot reference and estimate annual electricity use.
Open calculatorU-values and insulation
Calculate multilayer wall U-value, compare insulation options and estimate associated transmission heat loss.
Open calculatorHeat-pump and chiller buffer-water volume
Estimate useful system water volume and any additional buffer-vessel capacity needed to limit short cycling.
Open calculatorAdditional refrigerant charge
Estimate additional liquid-line refrigerant charge from fluid, internal diameter, added length and liquid temperature.
Open calculatorRefrigerant pressure-temperature converter
Convert refrigerant saturation temperature, absolute pressure and gauge pressure, including bubble and dew values for blends.
Open calculatorHVAC refrigeration diagnostics
Diagnostic aid using suction and discharge pressures, line temperatures, superheat, subcooling and heat-exchanger approaches.
Open calculatorVRF refrigerant concentration check
Indicative VRF refrigerant concentration and safety check using charge, room area, low-point height, ventilation and refrigerant class.
Open calculatorCold-water flow rate and pipe diameter
Check cold-water flow rate, velocity, pipe diameter, pressure loss and residual pressure.
Open calculatorCollective and commercial cold/hot water supply
Estimate diversified cold- and hot-water flow rates, pipe size, velocity, pressure loss and residual pressure.
Open calculatorCollective and commercial DHW production
Compare instantaneous, semi-instantaneous and storage DHW production using demand, duty and storage volume.
Open calculatorDHW circulation pump selection
Estimate DHW circulation heat loss, minimum return flow, pipe size, pressure loss and pump head.
Open calculatorRainwater storage tank volume
Estimate useful rainwater storage from roof area, rainfall, collection efficiency, daily demand and autonomy.
Open calculatorIndividual solar DHW preliminary sizing
Estimate DHW demand, collector area, storage volume, solar fraction, backup heat and indicative savings.
Open calculatorCollective solar DHW preliminary sizing
Estimate collective DHW demand, circulation losses, solar collector area, storage, backup heat and savings.
Open calculatorSolar thermal expansion vessel
Estimate solar-loop fluid volume, vapour reserve, pressures and minimum expansion-vessel capacity.
Open calculatorFuel lower and higher heating values
Convert fuel quantity to energy using indicative LHV and HHV values for common heating fuels.
Open calculatorQuick heating-energy estimate
Convert fuel or electricity use to useful heating energy and estimate an indicative heat-pump equivalent.
Open calculatorHeat-pump selection assistant
Compare air-to-air, air-to-water, water-source and ground-source heat pumps from project constraints.
Open calculatorInternational heating-energy comparison
Compare heating and DHW scenarios using user-entered climate, energy prices, efficiencies and carbon factors.
Open calculatorElectrical cable sizing
Estimate conductor size from load current, voltage drop and indicative corrected current-carrying capacity.
Open calculatorElectrical load assessment
Combine connected loads, diversity factors and power factors to estimate demand, apparent power and three-phase current.
Open calculatorElectric motor selection
Estimate a standard motor rating, nominal torque and current from mechanical duty and service conditions.
Open calculatorTransformer preliminary sizing
Estimate transformer kVA, low-voltage current and loading from connected power, diversity, power factor and reserve.
Open calculatorElectric motor starting assistant
Compare indicative starting currents for direct, star-delta, soft-starter and variable-frequency-drive starting.
Open calculatorReactive power compensation
Estimate capacitor-bank kvar from active power and present and target power factors.
Open calculatorLighting preliminary sizing
Estimate luminaire quantity, connected power, power density and annual energy using the lumen method.
Open calculatorThree-phase load balancing
Distribute single-phase circuits across a three-phase board and estimate phase imbalance.
Open calculatorCircuit-breaker protection assistant
Compare design current with corrected cable capacity and identify an indicative breaker rating and curve.
Open calculatorElectrical enclosure cooling
Estimate enclosure heat rejection and indicative cooling duty from internal losses and ambient conditions.
Open calculatorPhotovoltaic self-consumption and battery
Estimate annual PV production, self-consumption, export, battery capacity and indicative annual benefit.
Open calculatorGas flow rate and heat output
Convert gas appliance heat output to an indicative flow rate for common fuel gases.
Open calculatorComplete gas pipework network
Preliminary gas-pipe sizing for a small collective or individual network with up to three appliances.
Open calculatorSaturated steam properties
Read saturated-steam temperature, pressure, enthalpy, density and indicative pipe flow data.
Open calculatorChimney and flue preliminary sizing
Estimate combustion-gas flow, draught and an indicative circular flue diameter.
Open calculatorCompressed-air pipework sizing
Estimate compressed-air pipe diameter, velocity and pressure drop from flow, pressure and length.
Open calculatorPipe thermal expansion
Estimate axial thermal movement and an indicative expansion-loop dimension.
Open calculatorInsulation surface quantity
Estimate insulation and cladding surface for straight pipes, fittings and equipment.
Open calculatorWorkshop mechanical calculations
Quick workshop calculations for torque, power, force, pressure, speed and mechanical conversions.
Open calculatorEuler buckling
Estimate Euler critical load, slenderness and an indicative column safety ratio.
Open calculatorParallel key sizing
Estimate key forces and bearing and shear stresses for a keyed shaft connection.
Open calculatorLarge-radius sheet-metal bend development
Calculate neutral-axis bend allowance and flat length for a large-radius sheet-metal bend.
Open calculatorTIG welding settings
Indicative TIG current, polarity, tungsten and gas settings from material and thickness.
Open calculatorShielded-metal-arc welding settings
Indicative electrode diameter, polarity and current range from material thickness and joint.
Open calculatorOxy-acetylene welding settings
Indicative nozzle, gas-flow and filler guidance from material type and thickness.
Open calculatorTimber beam bending check
Estimate timber-beam bending stress, deflection and bearing from a simplified load case.
Open calculatorTimber deck and joist check
Estimate deck-board joist spacing and simplified timber-joist bending and deflection.
Open calculatorDomestic cold-water supply sizing
Estimate domestic cold-water demand, design flow, pipe diameter and water velocity from fixture units.
Open calculatorDomestic wastewater drainage sizing
Estimate domestic wastewater and soil-pipe sizes from sanitary-appliance discharge units.
Open calculatorHVAC system selection assistant
Compare suitable HVAC system families from building use, comfort needs, constraints and project priorities.
Open calculatorHVAC systems comparison
Compare common HVAC solutions for comfort, acoustics, hygiene, maintenance, cost, renovation and energy performance.
Open calculatorCommercial wastewater drainage sizing
Estimate probable wastewater flow and indicative branch, stack and collector sizes for commercial or multi-residential buildings.
Open calculatorRainwater drainage sizing
Estimate roof runoff and an indicative rainwater outlet or downpipe size from catchment area and rainfall intensity.
Open calculatorCollective demand-controlled ventilation sizing
Estimate minimum and maximum extract airflow, diversity, main duct sizes and indicative fan duty for collective housing.
Open calculatorIndividual dwelling ventilation sizing
Estimate extract airflow, main duct size and indicative fan electrical demand for an individual dwelling.
Open calculatorCollective heat-interface-unit primary sizing
Estimate diversified heating and DHW duty, primary flow, bypass flow, buffer volume and indicative pipe diameter for collective HIUs.
Open calculatorMechanical smoke-extract preliminary sizing
Estimate smoke extract and replacement-air flow rates, opening quantities and useful free areas.
Open calculatorIndustrial fire-protection assistant
Compare indicative industrial fire-protection approaches from hazard, occupancy, equipment and operational constraints.
Open calculatorDuct weight and treatment-area estimate
Estimate sheet-metal duct weight, insulation area and sprayed fire-protection area with an allowance factor.
Open calculatorEngineering unit converter
Convert common engineering units for length, area, volume, flow, mass, pressure, energy, power, angle and temperature.
Open calculatorPipe diameters: inches and millimetres
Convert inch dimensions and review common nominal sizes for steel, copper, PEX, multilayer and pressure PVC pipes.
Open calculatorHeating-energy price benchmark
Review indicative heating-energy prices, carbon factors and recent trends, with currency conversion for comparison.
Open calculatorHeating low-loss header without manifold
Estimate a low-loss header connected directly to secondary circuits, including flow rates, connections and main dimensions.
Open calculatorHeating manifold without low-loss header
Estimate heating manifolds connected directly to a generator, including circuit flows, mixed return temperature and primary size.
Open calculatorSplit air-conditioner diagnostic assistant
Guide basic maintenance checks from symptoms, filters, condensate, outdoor unit and supply-to-return air temperature difference.
Open calculatorRadiator output and water-temperature correction
Correct radiator output for a selected water-temperature regime and perform an indicative size check.
Open calculatorResidential distribution-board preconfiguration
Prepare an indicative circuit, row, protective-device and spare-capacity schedule for a dwelling distribution board.
Open calculatorSingle-phase and three-phase motor calculator
Calculate motor current, power or voltage with power factor, efficiency, apparent power and indicative starting current.
Open calculatorRequired electrical supply estimate
Estimate required subscribed or service capacity from connected loads, diversity and optional load shedding.
Open calculatorEarthing-system selection assistant
Compare TT, TN-S, TN-C and IT earthing arrangements from source, continuity, maintenance, risk and sensitive-load constraints.
Open calculatorTechnical acoustics calculator
Combine sound levels from several sources at different distances, with background noise and optional octave-band analysis.
Open calculatorRoom acoustics and RT60 estimate
Estimate room reverberation time, Schroeder frequency and additional absorption required to meet a target.
Open calculatorVentilation belt and pulley calculator
Calculate pulley ratio, driven speed, target airflow, pulley diameter and indicative belt speed.
Open calculatorRoof pitch and surface calculator
Calculate roof pitch, sloping length and true roof area from rise, horizontal run or plan dimensions.
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