Electrical Calculators
Six tools built on one calculation engine and one set of reference data, so the answers agree with each other. Each one shows the formula it used and the numbers that went into it.
DC · 1Ø · 3ØVoltage Drop CalculatorThe main calculator. DC, single-phase and three-phase, with reactance and temperature correction when you need them.12 V · 24 V · 48 VDC Voltage Drop CalculatorBattery, solar and automotive circuits at 12 V, 24 V and 48 V, where a few tenths of a volt matter.R + jX · PFAC Voltage Drop CalculatorSingle-phase and three-phase with power factor, conductor reactance and raceway type.mm² · metresCable Voltage Drop CalculatorCable runs in metres and conductor sizes in mm², for anyone working to metric cable data rather than AWG.AWG · kcmil · mm²Wire Size CalculatorThe smallest conductor that stays inside your drop limit, shown against the ampacity the size carries.L maxMaximum Cable Length CalculatorHow far you can run a given conductor before the drop crosses your limit.V = I × RResistor Voltage Drop CalculatorOhm’s law solved for voltage, current or resistance, with power dissipation and a series divider.TablesVoltage Drop ChartDrop per amp per 100 ft for every size and material, plus conductor resistance and ampacity tables.
Reading
Guides that explain the tools.
Each one answers a single question with the arithmetic shown.
Voltage Drop FormulaEvery formula, with each variable explained and its units named.Voltage Drop CalculationFive worked examples, start to finish, with the arithmetic shown.How to Calculate Voltage DropThe five-step method, and the three mistakes that cause most wrong answers.How to Measure Voltage DropThe voltage drop test with a multimeter, and why it beats a resistance reading.What Is Voltage Drop?What it is, why it happens, and what it does to equipment.Voltage Drop in CableHow length, size, material and temperature each move the number.Acceptable Voltage DropWhere 3% and 5% come from, and what status they actually have.Copper vs Aluminium ConductorsThe resistance difference, size for size, and what it costs you.