Calculators for MEP design work

125 free tools for HVAC, fire protection, plumbing, electrical and BMS engineers. Each one follows a named standard — ASHRAE, NFPA, IPC, NEC or IEC — and shows the working, so a result can be checked before it goes on a drawing.

Most used

Duct Sizer ProWorld-class duct sizing with visualization, SMACNA compliance, noise criteriaHVACTR to CFM CalculatorConvert cooling tonnage to airflow rateHVACCable Size CalculatorCable size in mm² or AWG by current, derating and voltage drop (IEC, BS 7671 & NEC)ElectricalFire Hydraulic CalculatorHazen-Williams friction loss and pressure calculationsFire FightingPump Head CalculatorCalculate total dynamic head for pumpsPlumbingBTU / AC Sizing CalculatorFind the right AC size for a room — BTU/hr, tons & kW from area, climate, sun, insulation & occupancyHVACCCTV Storage CalculatorCalculate NVR hard disk size (TB) from cameras, resolution, FPS, H.264/H.265 & retention days — with bandwidth & HDD suggestionsBMS & ELVUnit Converter ProConvert all MEP units - flow, pressure, power, temperatureUtility

HVAC

Professional HVAC engineering tools for duct sizing, cooling loads, ventilation, and system design per ASHRAE standards.

All 40 HVAC calculators
Duct Sizer ProWorld-class duct sizing with visualization, SMACNA compliance, noise criteriaDuct Size CalculatorSize round and rectangular ducts using velocity or equal friction methodTR to CFM CalculatorConvert cooling tonnage to airflow rateBTU / AC Sizing CalculatorFind the right AC size for a room — BTU/hr, tons & kW from area, climate, sun, insulation & occupancyCHW Pipe Size CalculatorSize chilled water pipes using ASHRAE limits (≤2″: 4 ft/s, >2″: 4 ft/100ft). US & Metric modes with velocity and head loss.Cooling & Heat Load CalculatorMulti-zone cooling & heating load (ASHRAE CLTD) — sensible/latent, TR, kW, SHR, supply CFM with whole-building rollup & diversityRefrigeration Pipe SizerSize copper suction, liquid & discharge lines — velocity, pressure drop & ΔT penalty for R410A, R32, R134a, R404A, R22 & R407C with oil-return checksFresh Air ACH CalculatorCalculate fresh air requirements based on air changes per hour

Fire Fighting

Professional fire protection engineering tools for sprinkler systems, hydraulic calculations, and suppression system design per NFPA standards.

All 14 Fire calculators
Fire Hydraulic CalculatorHazen-Williams friction loss and pressure calculationsSprinkler K-FactorCalculate sprinkler flow and pressure using K-factorWater/Fire Tank SizeSize fire water storage tanks based on demandFM200 & CO₂ CalculatorCalculate clean agent quantities for protected spacesPipe Thrust BlockSize concrete thrust blocks for pipe bendsFire Pump SelectionSelect fire pumps based on flow and pressureHydrant Flow TestAnalyze hydrant flow test data per NFPA 291Standpipe SystemSize standpipe systems per NFPA 14

Plumbing

Professional plumbing engineering tools for water supply, drainage, pump selection, and system design per IPC/UPC standards.

All 19 Plumbing calculators
Water Supply PipeSize water supply pipes based on flow and velocityPump Head CalculatorCalculate total dynamic head for pumpsWater Pipe Pressure DropCalculate pressure loss in water piping systemsDrainage Slope CalculatorCalculate drainage pipe slope and fallRainwater Pipe SizeSize rainwater downpipes and guttersPump HorsepowerCalculate pump motor power requirementsPipe Support SpacingHanger spacing and rod size per MSS SP-58, NFPA 13 and IPCMedical Gas Pipe SizingCopper pipe size for oxygen, medical air and vacuum (NFPA 99 / HTM 02-01)

Electrical

Professional electrical engineering tools for cable sizing, load calculations, transformer sizing, and system design per NEC/IEC standards.

All 31 Electrical calculators
Cable Size CalculatorCable size in mm² or AWG by current, derating and voltage drop (IEC, BS 7671 & NEC)Load Current CalculatorCalculate load current from power and voltagePower Factor CalculatorCalculate PF, kVA, kVAR & phase angle from kW, voltage and current — single & three phase with calculation stepsElectrical Panel Load CalculatorBuild a panel schedule with demand load, auto cable size (Cu/Al), voltage drop, derating & breaker sizing (IEC & NEC)Motor Starter SizingDOL and star-delta contactors, overload setting and motor FLC tableBusbar SizeCopper or aluminium phase, neutral and earth busbar sizesSolar PV System SizeSolar array kWp, number of panels, battery and inverter sizeBattery Backup Time CalculatorBackup hours from battery Ah and load, or batteries needed, with Peukert correction

BMS & ELV

Professional tools for Building Management Systems and Extra-Low Voltage design — CCTV storage, fire alarm, UPS sizing, points lists and building automation per NFPA, IEC and BACnet standards.

All 7 BMS & ELV calculators
CCTV Storage CalculatorCalculate NVR hard disk size (TB) from cameras, resolution, FPS, H.264/H.265 & retention days — with bandwidth & HDD suggestionsFire Alarm Battery CalculatorSize FACP standby batteries (Ah) per NFPA 72 — 24hr + 5min worksheet with device currents, derating & standard battery selectionUPS Sizing CalculatorSize UPS kVA rating & battery bank (Ah, 12V blocks) from load, power factor, growth margin & required backup runtimeBMS Points List CalculatorGenerate DI/DO/AI/AO points count from equipment schedule with DDC controller estimateCCTV Bandwidth CalculatorCalculate network bandwidth per camera and total NVR/switch loadPA Speaker & Amplifier CalculatorSpeaker quantity from area & SPL requirements with amplifier wattage sizingSmoke Detector Spacing CalculatorDetector count and layout per NFPA 72 or BS 5839-1

Utility

Essential reference tools, converters, and calculators for everyday MEP engineering work.

All 14 Utility calculators
Unit Converter ProConvert all MEP units - flow, pressure, power, temperatureMM to Inches ConverterConvert millimeters to inches (and inches to mm) instantly with rounding controlPipe Schedule ReferenceComplete pipe dimensions per ASME B36.10Wire Gauge ReferenceAWG to mm² conversion with NEC ampacityHatch Pattern GeneratorDraw a pattern on a grid and download an AutoCAD or Revit .pat fileMaterial Weight CalculatorCalculate weight of pipes, plates, bars, anglesProject Cost EstimatorEstimate MEP project costs by building typeLPG Tank SizeSize LPG storage tanks based on consumption

Free MEP Engineering Calculators — All Disciplines, One Place

MEPBase Tools provides 125 free, professional-grade calculators for MEP (Mechanical, Electrical & Plumbing) engineers, designers, estimators and site teams. Every tool shows its formula, references and — where useful — worked examples and reference charts, so you can verify the math instead of trusting a black box.

HVAC Design

Size ducts with the online ductulator, convert TR to CFM, estimate cooling loads, size boiler feed pumps and refrigerant lines — per ASHRAE and SMACNA practice. All HVAC tools →

Fire Protection

Hydraulic calculations, sprinkler K-factors, fire pump selection, FM200/CO₂ clean agent sizing and tank capacity per NFPA codes. All fire fighting tools →

Plumbing & Public Health

Water supply pipe sizing by fixture units (WSFU), pump head and NPSH, hot water demand, and drainage design per IPC. All plumbing tools →

Electrical Power

Cable sizing, voltage drop, breaker selection, transformer and generator sizing, power factor and earthing per NEC and IEC methods. All electrical tools →

BMS & ELV

Low-voltage and building automation design: CCTV storage (NVR hard disk size in TB), fire alarm battery sizing, UPS sizing and BMS points lists. Explore BMS & ELV →

Use these tools for preliminary design, quick checks and verification. Final designs should always be confirmed against project specifications, manufacturer data and applicable local codes.

Questions

Are MEPBase calculators free to use?

Yes — all 125 calculators are completely free with no registration, no sign-up and no limits. They work on desktop, tablet and mobile.

Which standards are the calculators based on?

Tools follow industry standards including ASHRAE Handbooks and SMACNA (HVAC), NFPA codes (fire protection), IPC (plumbing), NEC/IEC (electrical) and NFPA 72 / IEC 62676 (BMS & ELV). Each tool lists its references.

Can I use these tools for final engineering design?

The calculators are intended for preliminary sizing, quick checks and verification. Final designs must always be verified against project specifications, manufacturer data and applicable local codes by a qualified engineer.