Free Engineering Calculators & Tools Online
109 calculators
Fire Protection
1Plumbing
12Fixture Unit Calculator
Calculate water supply fixture units (WSFU) and determine pipe sizing, peak demand flow rates, and pressure requirements based on IPC P-2903 standards.
DWV Sizing Calculator
Calculate drain, waste, and vent pipe sizes based on IPC Chapter 4 standards. Determine DFU totals, branch drain sizes, building drain sizing, and vent configurations.
Sump Pump Calculator
Calculate sump pump capacity based on drainage area, soil percolation, and water table conditions per IPC Section 1113. Determine pump size, basin requirements, cycle rates, and battery backup needs.
Hot Water Recirculation Calculator
Calculate recirculation pump sizing, energy costs, and payback period for instant hot water delivery systems per ASHRAE 90.1 and IPC Chapter 6. Analyze heat loss, water waste savings, and operating modes.
Backwater Valve Sizing Calculator
Size backwater/check valves for sewage backup protection per IPC Section 715, ASME A112.14.1, and CSA B181.1. Calculate valve type, installation requirements, cost analysis, and maintenance schedules.
Pipe Network Solver
Solve complex looped pipe networks using Hardy-Cross method with automatic loop detection and flow balancing
Water Pressure Loss
Professional tool for calculating water pressure loss in pipes using Darcy-Weisbach or Hazen-Williams equations. Supports copper, steel, PVC, and PEX pipes with fitting loss calculations.
Boiler DHW
Calculate boiler capacity, storage requirements, and energy consumption for domestic hot water systems based on usage patterns, recovery time, and peak demand.
Hydropneumatic System
Calculate hydropneumatic tank volume, pump capacity, and energy consumption for residential, commercial, and industrial water supply systems with constant pressure.
Pipe Insulation Thickness Calculator
Calculate required insulation thickness for pipes based on heat loss limits, temperature control, and condensation prevention. Get standard thickness recommendations and thermal performance.
Water Tank Calculator
Calculate water storage tank capacity for residential and commercial buildings based on daily consumption and storage requirements
Grease Separator Calculator
Size grease traps and separators for commercial kitchens based on EN 1825 standards. Calculate required capacity for restaurants, hotels, and food service establishments
Structural
4Snow Load Calculator
Calculate roof snow loads per ASCE 7-22 Chapter 7 including flat roof, sloped roof, and minimum snow loads
Steel Beam Calculator
Design steel beams per AISC 360-22 with lateral-torsional buckling analysis, shear checks, and deflection verification
Seismic Base Shear Calculator
Calculate seismic base shear per ASCE 7-22 Equivalent Lateral Force (ELF) procedure with vertical force distribution
Wind Load Calculator
Calculate MWFRS wind loads per ASCE 7-22 Chapters 26-31 Directional Procedure
Utilities
19Electricity Bill Estimator
Estimate your monthly electricity bill based on appliance usage, regional rates, and rate structures. Includes detailed breakdowns by category, seasonal analysis, and personalized savings recommendations.
PMV/PPD Thermal Comfort Calculator
Calculate Predicted Mean Vote (PMV) and Predicted Percentage Dissatisfied (PPD) for indoor thermal comfort assessment using Fanger's model according to ASHRAE 55-2020 and ISO 7730.
WBGT Heat Stress Calculator
Calculate Wet Bulb Globe Temperature (WBGT) for occupational heat stress assessment with OSHA/NIOSH threshold limits and work/rest cycle recommendations.
Tile Calculator
Calculate the number of tiles needed for your floor, wall, or surface project with wastage factors, layout patterns, and cost estimates.
Roofing Calculator
Calculate roofing materials including shingles, metal panels, tiles with pitch adjustment, underlayment, and accessory estimates
Paint Calculator
Calculate paint quantities and costs for interior/exterior surfaces with texture adjustments, primer options, and opening deductions
Gravel Calculator
Calculate gravel volume, weight, and cost for landscaping, driveways, and construction projects
Concrete Calculator
Calculate concrete volume and material quantities for slabs, footings, columns, walls, and more. Includes mix ratios and bag estimates.
Square Footage Calculator
Calculate area for rectangles, circles, triangles, and other shapes with unit conversions and material estimates.
Stair Calculator
Calculate stair dimensions including rise, run, angle, and stringer length. Verify building code compliance for IRC, IBC, and OSHA standards.
BTU Calculator
Calculate the recommended BTU capacity for air conditioning or heating based on room size, insulation, climate, and occupancy. Uses EnergyStar guidelines for accurate AC sizing.
Density Calculator
Calculate density, mass, or volume from the other two values using the equation ρ = m/V. Includes unit conversions and material density comparisons.
Heat Index Calculator
Calculate the heat index (feels-like temperature) based on air temperature and humidity using NOAA/NWS algorithms. Includes dew point, wet bulb, humidex, and health recommendations.
Foot-Candles to Lux Converter
Convert between foot-candles (US) and lux (metric) illuminance units. Compare against IES and EN lighting standards for various applications.
Energy Cost Comparison Calculator
Compare HVAC system lifecycle costs including equipment, installation, energy, and maintenance. Analyze NPV, payback periods, and CO2 emissions across heat pumps, furnaces, and boilers over a 20-year period.
Carbon Footprint Calculator
Calculate your personal or business carbon footprint in tonnes CO₂e. Compare to Paris 2030 targets, see EPA/DEFRA emission breakdowns, and get reduction tips.
AC Running Cost Calculator
Calculate your air conditioning electricity costs based on unit capacity, SEER rating, usage patterns, and regional electricity rates. Includes monthly breakdown, efficiency comparison, and upgrade ROI analysis.
EV vs Gas TCO Calculator
Compare the Total Cost of Ownership between Electric Vehicles and Gas vehicles. Includes purchase costs, fuel/energy, maintenance, depreciation, incentives, and environmental impact analysis with break-even projections.
Solar Panel Payback Calculator
Calculate your solar panel investment ROI with NPV, IRR, and payback period analysis. Uses NREL PVWatts methodology for accurate production estimates. Includes Federal ITC (30%), state incentives, financing options, and 25-year cash flow projections.
Electrical
52AWG to MM Converter
Convert American Wire Gauge (AWG) to metric measurements including diameter, cross-sectional area, resistance, and ampacity ratings based on ASTM B258 and NEC 2023 standards.
Lumen to Watt Converter
Convert between lumens and watts for different light sources. Calculate equivalent wattages, energy savings, and find incandescent replacements using ENERGY STAR standards.
Lux to Lumen Converter
Convert between lux (illuminance) and lumens (luminous flux) based on area. Calculate lighting requirements for any space with standard recommendations.
Candela to Lumen Converter
Convert between candela (luminous intensity) and lumens (luminous flux) based on solid angle and beam pattern. Calculate light output for spotlights, LEDs, and isotropic sources.
Panel Schedule Builder
Create NEC 2023 compliant electrical panel schedules with automatic load calculations, breaker sizing, and wire selection. Perfect for residential and commercial electrical design.
Volt to Watt Calculator
Calculate power in watts from voltage in volts and current in amperes. Supports DC, AC single-phase, and AC three-phase electrical systems.
Watt to kWh Calculator
Calculate energy consumption in kilowatt-hours from power in watts and operating time. Perfect for estimating electricity costs and appliance usage.
kWh to kW Converter
Calculate power in kilowatts from energy consumption in kilowatt-hours and time period. Useful for analyzing electricity bills and appliance consumption.
Power Calculator
Calculate electrical power using P = V × I, P = V²/R, or P = I²R formulas. Supports DC circuits and AC systems with power factor correction. Use this calculator for load analysis, circuit design, and equipment sizing. Outputs power in watts, kilowatts, and horsepower with real/apparent power breakdown for AC loads.
kW to kVA Converter
Convert real power (kW) to apparent power (kVA) using power factor for transformer and generator sizing. Apparent power determines the required rating of transformers, UPS systems, and generators. Also calculates reactive power (kVAR) to assess power factor correction needs per IEEE 519 and utility requirements.
mAh to Wh Converter
Convert battery capacity from milliamp-hours (mAh) to watt-hours (Wh) using Wh = mAh × V / 1000. Essential for comparing batteries with different voltages, calculating device runtime, and verifying airline carry-on battery limits (100Wh). Used for smartphones, laptops, power banks, and electric vehicle battery analysis.
Wh to mAh Converter
Convert battery energy from watt-hours (Wh) to milliamp-hours (mAh) using mAh = Wh × 1000 / V. Use this calculator to compare batteries at different voltages, determine replacement battery specifications, and verify manufacturer capacity claims. Common for laptop batteries (typically 40-100Wh) and power bank comparisons.
Joule to Watt Converter
Convert energy in joules to average power in watts using P = E/t. Use this calculator to determine power consumption from energy measurements, analyze battery discharge rates, or convert between energy and power units. Supports conversions to kW, MW, and other power units. Essential for energy auditing and electrical system analysis.
Watt to Amps Converter
Calculate current in amperes from power in watts and voltage in volts. Supports DC, AC single-phase, and AC three-phase systems.
Watt to Volt Converter
Calculate voltage in volts from power in watts and current in amperes. Supports DC, AC single-phase, and AC three-phase systems.
Watt, Volt, Amp Calculator
Calculate power, voltage, and current relationships using Ohm's Law and power formulas for DC and AC circuits
Amps to kW Converter
Calculate power in kilowatts from current in amperes and voltage. Supports DC, AC single-phase, and AC three-phase systems.
Volt to kW Calculator
Convert voltage to kilowatts using current and power factor for AC and DC systems
Watt to VA Calculator
Convert real power (watts) to apparent power (VA) using VA = W / PF. Use this calculator to size UPS systems, transformers, and generators based on equipment wattage ratings. Accounts for power factor to ensure adequate capacity for reactive loads like motors and computers. Outputs kVA rating for equipment specification.
Watt to kVA Calculator
Convert real power (watts) to apparent power (kilovolt-amperes) using power factor
VA to kW Calculator
Convert apparent power (volt-amperes) to real power (kilowatts) using power factor
kW to VA Calculator
Convert real power (kilowatts) to apparent power (volt-amperes) using power factor
kVA to Watt Calculator
Convert apparent power (kVA) to real power (watts) using power factor for electrical system calculations
Volt to Amp Calculator
Convert voltage to current (amperes) using power and resistance for DC and AC circuits
Volt to Joule Calculator
Convert voltage to energy (joules) using electric charge for capacitor and battery calculations
Joule to Volt Calculator
Convert energy (joules) to voltage using electric charge for capacitor and battery calculations
Watt to Joule Calculator
Convert power (watts) to energy (joules) using time for energy consumption calculations
Volt to Electron Volt Calculator
Convert voltage (V) to electron volts (eV) for particle physics and semiconductor applications
kVA to kW Converter
Calculate real power in kilowatts from apparent power in kilovolt-amps using power factor.
kWh to Watt Converter
Calculate power in watts from energy consumption in kilowatt-hours and time duration in hours.
Amps to Watt Converter
Calculate power in watts from current in amperes and voltage in volts. Supports DC, AC single-phase, and AC three-phase systems.
Amps to VA Converter
Calculate apparent power in volt-amperes from current in amperes and voltage in volts. Supports single-phase and three-phase systems.
kW to Amps Converter
Calculate current in amperes from power in kilowatts and voltage in volts. Supports DC, AC single-phase, and AC three-phase systems with power factor.
VA to Amps Converter
Calculate current in amperes from apparent power in volt-amperes and voltage in volts. Supports single-phase and three-phase systems.
Resistor Color Code Calculator
Decode 4, 5, and 6-band resistor color codes. Find resistance values, tolerance, and temperature coefficients instantly.
LED Resistor Calculator
Calculate the ideal current-limiting resistor for LED circuits. Get resistor values, power ratings, and actual current with standard E24 series resistors.
Capacitor Energy Calculator
Calculate energy stored in capacitors. Find energy in joules, watt-hours, charge stored, and discharge characteristics for any capacitor.
Inductor Energy Calculator
Calculate energy stored in inductors and magnetic fields. Find energy in joules, watt-hours, magnetic flux, and voltage spikes during discharge.
Battery Life Calculator
Calculate battery runtime and discharge characteristics. Get estimates for runtime, C-rate, power consumption, and warnings for any battery-powered device.
Amps to Volts Calculator
Convert current (amps) to voltage (volts) using Ohm's Law (V = I × R) or power relationship (V = P / I). Use this calculator for troubleshooting circuits, sizing conductors, and verifying voltage drop across loads. Essential for field measurements when voltage readings aren't available but current and power/resistance are known.
VA to Watts Calculator
Convert apparent power (VA) to real power (watts) using power factor with W = VA × PF. Use this calculator to determine actual power consumption from UPS or transformer ratings, understand equipment efficiency, and verify utility billing. Essential for comparing equipment rated in VA vs. watts and estimating actual energy costs.
kW to kWh Calculator
Convert power (kW) to energy consumption (kWh) over time using E = P × t. Essential for estimating electricity costs, sizing battery storage systems, and calculating solar panel energy production. Use this calculator for energy audits, utility bill analysis, and comparing equipment operating costs over monthly or annual periods.
Amps to kVA Calculator
Convert current (amps) to apparent power (kilovolt-amperes) for transformer sizing, generator selection, and electrical panel design. Essential for determining UPS capacity, sizing service entrance equipment, and specifying backup power systems. Supports single-phase and three-phase configurations per IEEE and IEC standards.
Energy Consumption Calculator
Calculate daily, monthly, and yearly energy consumption from power and usage time
Voltage Divider Calculator
Enter 3 of 4 values (input voltage, R1, R2, output voltage) to calculate the 4th value using the voltage divider formula.
Ohm's Law Calculator
Enter any 2 values (voltage, current, or resistance) to calculate the third value and power using Ohm's Law.
Short Circuit Calculator
Calculate short circuit current and breaking capacity requirements for electrical protection design.
Cable Sizing Calculator
Calculate minimum cable cross-section based on current rating, voltage drop, and installation conditions
Voltage Drop Calculator
Calculate voltage drop in electrical cables according to IEC 60364-5-52, NEC, and BS 7671 standards
Power Factor Calculator
Calculate power factor from real, reactive, and apparent power measurements. Size capacitor banks for power factor correction to avoid utility penalties (typically required to maintain PF > 0.9). Outputs required kVAR compensation and capacitor sizing. Essential for industrial facilities with large inductive loads (motors, transformers).
Transformer Sizing Calculator
Calculate required transformer capacity based on load power, voltage levels, power factor, and future expansion needs. Get standard transformer ratings and loading percentages.
kVA to Amps Converter
Convert apparent power (kVA) to current (amps) for sizing cables, breakers, and protective devices. Use when you know transformer or generator rating in kVA and need to select appropriately rated conductors and overcurrent protection. Supports single-phase and three-phase systems with line-to-line and line-to-neutral voltage options.
Ventilation
10Duct Network Designer
Design HVAC duct systems with automatic sizing, pressure drop calculations, and critical path analysis. Essential for fan selection and system balancing.
Fan/System Curve Calculator
Interactive tool to analyze fan performance curves, system resistance curves, and determine the operating point. Essential for HVAC fan selection and VFD optimization.
Duct Pressure Loss
Calculate pressure drop in ductwork including friction losses and fitting losses based on airflow, duct dimensions, and material properties.
Fresh Air Flow
Determine the required fresh air flow for different space types based on occupancy and air quality standards per ASHRAE 62.1.
Pool Ventilation
Determine ventilation and dehumidification requirements for swimming pools based on pool area, temperature, and humidity.
HRV Sizing
Determine the required size and performance of heat recovery ventilators based on space requirements and efficiency.
Kitchen Hood
Determine the required exhaust flow and makeup air for kitchen hoods based on cooking type and hood area.
Parking Ventilation
Determine ventilation requirements for parking garages based on area, occupancy, and CO dilution requirements.
Shelter Ventilation
Determine ventilation requirements for emergency shelters based on occupancy and shelter type.
Duct Sizing Calculator
Size HVAC air ducts using equal friction or velocity methods per SMACNA and ASHRAE standards
Heating
6Manifold/Collector
Design hydronic manifold/collector assemblies for radiant floor heating per EN 1264. Calculates manifold size based on number of circuits and total flow rate, determines header diameter to maintain velocity below 1.5 m/s, and provides balancing valve settings for equal flow distribution. Includes circuit length recommendations for 16mm and 20mm pipe.
Expansion Tank
Size expansion vessels for closed-loop hydronic heating systems per EN 12828 and EN 13831. Calculates water volume expansion from temperature rise, determines pre-charge and operating pressures based on static height, and outputs minimum vessel volume with acceptance factor. Prevents pressure relief valve discharge and system air problems.
Balance Vessel
Size balance vessels (buffer tanks) for hydronic heating systems per EN 12828 and TS 2164. Prevents boiler short-cycling in modular installations, provides hydraulic separation between primary and secondary circuits, and ensures minimum flow requirements are met. Critical for condensing boilers, heat pump systems, and multi-zone configurations.
Circulation Pump
Size circulation pumps for hydronic heating and cooling systems per EN 12828. Calculates required flow rate from heat load and temperature differential, then determines pump head from pipe friction losses and fittings. Outputs operating point for pump curve selection. Essential for radiant floor heating, fan coil systems, and chilled water loops.
Radiator Selection
Select radiators based on room heat loss per EN 442 testing standards. Calculates required radiator output considering supply/return temperatures and room temperature, then matches to manufacturer catalogs. Outputs panel type (Type 11, 21, 22, 33), dimensions, and element count. Includes correction factors for low-temperature systems.
Heat Loss Calculator
Calculate room-by-room heat loss for heating system sizing per EN 12831 and TS 2164. Accounts for transmission losses through walls, windows, roof, and floor, plus ventilation/infiltration loads. Outputs design heat load in watts for radiator selection, boiler sizing, and heat pump capacity. Includes insulation quality corrections.
Cooling
2Psychrometric Calculator
Calculate air properties, psychrometric processes, and air mixing using ASHRAE standards
Cooling Load Calculator
Calculate building cooling loads using simplified ASHRAE methodology. Accounts for transmission through walls/roof/windows, solar heat gain, internal loads (occupants, lighting, equipment), and ventilation requirements. Outputs sensible and latent loads for air conditioning system sizing. Ideal for preliminary design and load estimation.
Mechanical
3Pump Sizing Calculator
Professional pump sizing calculator that determines hydraulic power, shaft power, motor requirements, and NPSH for centrifugal and positive displacement pumps. Based on Hydraulic Institute Standards and ASME B31 series.
Horsepower Calculator
The Horsepower Calculator is a practical tool that helps you calculate the power generated by an engine. You can determine your engine power using torque and RPM data or 402-meter quarter-mile performance.
Beam Deflection Calculator
Calculate beam deflection, moment of inertia, and structural acceptability using Roark's formulas