Ohm's Law Calculator
Enter any two of volts, amps, ohms, or watts and get the other two — the most-used formula on the job.
Voltage Drop Calculator
Check the voltage lost on a cable run by gauge, length, load, and material — with the percentage drop.
Wire Size Calculator
Find the smallest AWG conductor that keeps voltage drop under 3% and safely carries your load current.
Watts / Amps / Volts Converter
Convert between watts, amps, and volts for DC and single-phase AC circuits, with power factor.
Electricity Cost Calculator
See what an appliance really costs to run per day, month, and year from its wattage and your kWh rate.
Conduit Fill Calculator
How many THHN wires fit in an EMT conduit at the standard 40% fill? Pick a gauge and trade size to find out.
Resistor Color Code Calculator
Read any 4-band resistor: choose the band colours and get the resistance value and tolerance.
Voltage Divider Calculator
Work out the output voltage of a two-resistor divider from the input voltage and resistor values.
Series & Parallel Resistance
Combine up to five resistors in series or parallel and get the total equivalent resistance instantly.
Battery Life Calculator
Estimate how long a battery will run a load, from capacity in mAh and the current the load draws.
Why electricians keep ElectricianKit bookmarked
The maths you reach for every day
Sizing a run, checking a drop, reading a resistor, estimating a customer's running cost — these are the same handful of calculations, repeated on almost every job. ElectricianKit puts all of them on one fast page set, with the formula printed next to every answer so you can double-check the reasoning, not just the number.
Built around standard references
Wire tables use the standard circular-mil areas for AWG conductors, conduit fill uses the familiar 40% rule for three or more conductors, and ampacity notes follow common 75°C copper and aluminium ratings. Everything is labelled as a planning estimate — your local code book stays the final word.
Private and instant
Every calculation runs on your own device. Nothing you type is sent anywhere, and there is no account to create.
Frequently asked questions
Is ElectricianKit free to use?
Yes. Every calculator is completely free, with no account, subscription, or hidden charges.
Can I rely on these results for an installation?
Use them for planning, quoting, and learning. Final installation decisions must follow your local electrical code (such as the NEC) and, where required, a licensed electrician.
Which wire tables does the site use?
AWG circular-mil areas from the standard conductor table, resistivity constants K = 12.9 for copper and 21.2 for aluminium, and common 75°C ampacity ratings.
Does the site work on a phone?
Yes. The layout is mobile-first and every calculator is usable one-handed on a phone screen.