Useful answers.
Understand the working.
Calculators and worksheets for the subjects you study and the problems you meet in practice. Work through an example, try your own values, then test the same ideas in exam practice.
Voltage drop calculator
Follow conductor resistance and the complete electrical path in a licensing calculation. State whether the supply is DC, single-phase AC or balanced three phase before choosing the multiplier.
Open tool →FREE TOOLOhms law calculator
Choose the two quantities actually given in a resistive circuit question. Show the rearrangement rather than guessing from a formula triangle.
Open tool →FREE TOOLAC power calculator
Separate real power from apparent and reactive power for a sinusoidal load. For three-phase questions, identify line voltage and current explicitly.
Open tool →FREE TOOLSeries and parallel resistance calculator
Compare the same resistors connected in series and parallel. Check whether the equivalent must be larger than the largest resistor or smaller than the smallest.
Open tool →FREE TOOLElectricity use calculator
Translate watts and operating time into the energy charged by a flat tariff. Distinguish a device power rating from actual period energy.
Open tool →Tools that connect the calculation to the concept
Each tool shows its method, units and assumptions, together with two worked examples. Example values are for learning; replace them with your own measurements or documented inputs. The related study links take you to the matching certification topic on Electrical Exam.
Worksheets run in your browser. We do not send entered measurements or report text to a calculation service. Where export is available, you choose when to save the file locally.
Check the boundary of the answer
A useful result starts with the right inputs and an appropriate method. These tools explain what is calculated and what the method leaves out. User-supplied criteria remain identified as supplied criteria; a calculation does not automatically approve equipment, certify an inspection or establish regulatory compliance.