Voltage drop
Estimate cable voltage drop for one- and three-phase circuits.
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Maximum cable length
Estimate maximum cable length at a selected voltage-drop limit.
Explore tool →Cable resistance
Calculate conductor resistance at different temperatures.
Explore tool →Ohm’s law
Explore voltage, current, resistance and power.
Explore tool →Three-phase power
Calculate active, reactive and apparent power.
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Estimate energy consumption and cost.
Explore tool →Power factor correction
Estimate capacitor compensation for inductive loads.
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Practice three-phase and earthing connections.
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Review installation conditions before choosing a cable.
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⚠ Results are educational approximations and do not replace measurements, regulations or professional verification.
01 · CABLES
Voltage drop
Estimate conductor voltage drop for copper or aluminium, single- or three-phase circuits.
02 · POWER
Three-phase power
Calculate active power, apparent power and reactive power from voltage, current and power factor.
03 · FUNDAMENTALS
Ohm's law
Calculate current, voltage, resistance and power using any two suitable electrical values.
04 · CABLES
Cable resistance
Estimate DC conductor resistance at a selected operating temperature.
05 · ENERGY
Energy cost
Estimate kWh consumption and electricity cost from load and operating hours.
06 · POWER
Power factor correction
Estimate capacitor compensation kvar for an inductive load.
07 · FIELD TOOLS
Maximum cable length
Find the longest approximate conductor run for a chosen voltage-drop percentage.
Guide & standalone tool →08 · INSTALLATION
Installation conditions
Review burial, tray, conduit, temperature and grouping factors before sizing a cable.
Open checklist →Cable resistance
Approximate DC resistance of a single conductor. Length is the actual conductor length, not a complete circuit loop.
Enter values and calculate.
R(T) = ρ₂₀ × L/A × [1 + α₂₀ × (T − 20)]
Approximation using reference resistivity and temperature coefficient; actual cable resistance varies with construction, tolerances and AC effects.
Electricity cost calculator
Enter values and calculate.
Energy (kWh) = power (W) × hours/day × days / 1000
Energy-only estimate; excludes fixed charges, demand charges, taxes and tariff variation unless included in your entered unit price.
Power factor correction
For a balanced sinusoidal inductive load, estimate the capacitive reactive power required to improve displacement power factor.
Enter values and calculate.
Qc = P × [tan(acos(PF₁)) − tan(acos(PF₂))]
Does not size individual capacitors. Harmonics, resonance, switching, overcompensation and equipment ratings require professional assessment.
Voltage drop calculator
Resistive approximation at 20°C. Enter one-way conductor length. For AC circuits, reactance is excluded.
Enter values and calculate.
ΔU ≈ k × I × ρ × L / A, where k = 2 (single-phase) or √3 (three-phase)
For preliminary estimates only. Final cable sizing must consider conductor temperature, power factor, reactance, installation method, protection, local regulations and permissible voltage drop.
Maximum cable run length
Estimate the maximum one-way conductor length for a chosen voltage-drop budget. Resistive approximation only; this does not verify cable ampacity or protective-device disconnection.
Enter values and calculate.
Lmax = (U × limit% / 100) × A / (k × I × ρ(T))
For AC installations, reactance and load power factor can affect results. A chosen percentage is a user-defined design target, not a universal code limit. Verify against the applicable installation standard and cable data.
Three-phase power calculator
Balanced three-phase AC system using line-to-line voltage and line current.
Enter values and calculate.
S = √3 × U × I; P = S × PF; |Q| = S × √(1 − PF²)
Reactive power magnitude is shown. Its sign depends on whether the load is inductive or capacitive.
Ohm's law calculator
Choose two known values. The remaining values are calculated for a resistive DC load.
Enter values and calculate.
V = I × R; P = V × I = I² × R = V² / R
Applies to ideal resistive circuits. Do not use as a substitute for electrical safety verification.
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Each tool is designed to be useful without a login, and formulas remain visible so results can be checked independently. Calculations are performed locally in your browser.
Detailed guides
Voltage drop formula and worked example · Three-phase power equations · Ohm’s law reference and examples · Cable resistance · Electricity cost · Power factor correction · Maximum cable length