Electrical, Electronics, Solar & Energy Calculators

Ohm's law, cable sizing, solar, batteries and power.

65 tools · 100% Free · Works Offline

Browse by Topic

Popular Calculators

Ohms Law CalculatorSolve for voltage, current, resistance or power using Ohm's law from any two known values, free…

Electricity Cost CalculatorEstimates the running cost of an appliance from its power in watts, hours of use and your…

Energy Cost CalculatorWork out the running cost of an appliance or device from its wattage, usage hours and…

Solar Output CalculatorEstimate daily and monthly solar panel energy output from system size, sunlight hours and…

All Electrical, Electronics, Solar & Energy Calculators (65)

Guide to Electrical Calculators

This hub covers the working maths behind electrical, electronics and solar/energy jobs: Ohm's law and power conversions, cable sizing and voltage drop, three-phase and fault current, circuit and semiconductor design, and PV/battery/off-grid sizing. It is used by sparkies and apprentices, solar and off-grid installers, plant and mine-site electrical crews, panel builders and hobbyist electronics tinkerers.

Electrical basics: current, power and conversions

Start here to turn nameplate figures into the numbers other tools need — use watts/amps and kVA/kW conversions to find a load, then Ohm's law, power factor and single/three-phase for the underlying maths.

Ohms Law Calculator Watts to Amps Calculator Amps to Watts Calculator kVA to kW Calculator Power Factor Calculator Three Phase Power Calculator Single Phase Power Calculator Reactive Power (kVAR) Calculator

Cables, conduit and voltage drop

Once you know the load current and run length, size the conductor and check volt-drop; use the AS/NZS 3008 and ampacity tools for conductor selection, derating for buried or grouped runs, and conduit/tray fill for how much fits.

Cable Sizing Calculator (AS/NZS 3008)Wire Ampacity Calculator Voltage Drop Calculator Underground Cable Derating Calculator High Voltage Cable Sizing Calculator Conduit Fill Calculator Cable Tray Fill Calculator Wire Gauge Converter

Protection, motors and site loads

For switchboards and machinery, work from the load to breaker and fault ratings, and use the motor tools when starting current and inrush volt-drop drive the design.

Circuit Load Calculator Maximum Demand Calculator Circuit Breaker Sizing Calculator Prospective Fault Current Calculator Motor Full Load Amps Calculator Motor Starting Current Calculator Motor Starting Voltage Drop Calculator Earthing Electrode Resistance Calculator

Solar, batteries and off-grid

Plan a system by working from daily load and irradiance to panel count, then size the string, charge controller, inverter and battery bank; use payback and off-grid tools to check the economics.

Solar Output Calculator Solar Panel Count Calculator Solar PV String Sizing Calculator Solar Charge Controller Size Calculator Battery Bank Size Calculator Inverter Sizing Calculator Off Grid Load Calculator Solar Payback Period Calculator

Electronics: circuits and components

For board-level design use the passive-network and timing tools — resistor/capacitor/inductor combinations, LED current-limiting, dividers, and RC timing and resonance.

Parallel Resistance Calculator Series Resistance Calculator LED Resistor Calculator Voltage Divider Calculator Capacitor Energy Calculator RC Time Constant Calculator Resonant Frequency Calculator (LC Circuit)Transformer Turns Calculator

Energy use and running costs

To estimate bills and savings, convert power and runtime to kWh, then apply a tariff; use the LED and generator-fuel tools for comparing upgrade or off-grid running costs.

Watts to kWh Calculator Electricity Cost Calculator Energy Cost Calculator LED Savings Calculator Battery Life Calculator Generator Fuel Consumption Calculator

Important calculation notice

These calculators are intended for education, estimation and preliminary checks. Verify all inputs, units, assumptions, material properties and applicable standards. Safety-critical or final engineering designs should be checked by a suitably qualified professional.

Related calculator categories

Telecommunications & Radio Audio, Acoustics & AV Automotive, 4WD, Towing & EV HVAC, Plumbing, Water & Building Services Networking, IT & Sysadmin Structural, Materials, Mechanical & Workshop

Electrical, Electronics, Solar & Energy Calculators

Browse by Topic

Popular Calculators

All Electrical, Electronics, Solar & Energy Calculators (65)

Electrical Fundamentals10 calculators

Circuits & Electronics17 calculators

Cables, Fault & Protection22 calculators

Solar & Off-Grid11 calculators

Energy Use & Costs5 calculators

Related calculator categories