Calculator Directory
Electrical Calculators
Estimate electricity use and operating cost with clear units and formulas for everyday planning.
Electricity Cost Calculator Translate watts, hours, and electricity rates into monthly and annual cost.
Ohm’s Law Calculator Solve voltage, current, resistance, and power from two known values.
Watts to Amps Calculator Convert real power to current for DC and common AC systems.
Amp Hours to Watt Hours Estimate nominal energy, usable energy, and battery runtime.
Energy Use Calculator Estimate daily, monthly, and annual appliance kWh.
Voltage Divider Calculator Calculate an unloaded two-resistor voltage divider.
Resistor Network Calculator Compare series and parallel equivalents for three positive resistors.
Capacitor Energy Calculator Calculate ideal capacitor energy and charge magnitude from microfarads and voltage.
Capacitive Reactance Calculator Calculate ideal capacitive reactance from frequency and capacitance.
Inductive Reactance Calculator Calculate ideal inductive reactance from frequency and inductance.
RC Time Constant Calculator Calculate RC time constant and ideal charging or discharging voltage at a chosen time.
RL Time Constant Calculator Calculate RL time constant and current after a DC voltage step.
LC Resonant Frequency Calculator Calculate ideal LC resonant frequency from inductance and capacitance.
Single-Phase Power Calculator Estimate apparent power, real input power, and useful output power for a single-phase AC load.
Three-Phase Power Calculator Estimate balanced three-phase apparent, real, and useful output power from line voltage and line current.
Two-Wire Voltage Drop Calculator Estimate DC or single-phase two-wire voltage drop from current, one-way length, and conductor resistance.
Battery Runtime Calculator Estimate usable battery energy and runtime from nominal voltage, amp-hours, allowed depth of discharge, efficiency, and load.
Battery Series and Parallel Calculator Calculate ideal pack voltage, amp-hour capacity, watt-hours, and cell count from a series-parallel arrangement.
LED Series Resistor Calculator Estimate a current-limiting resistor and its power dissipation for LEDs connected in series to a DC source.
Transformer Turns Ratio Calculator Calculate ideal transformer voltage and current relationships from primary and secondary turns.
Power Factor Calculator Calculate power factor, reactive power, and phase angle from real power and apparent power.
RMS and Peak Voltage Calculator Convert RMS voltage to peak and peak-to-peak values for an ideal sine wave.
dBm to Watts Calculator Convert logarithmic dBm power to milliwatts and watts, with an ideal RMS voltage for a chosen resistive load.
Solar Panel Output Calculator Estimate solar-array energy from panel rating, panel count, peak-sun hours, and total system losses.
Inverter Size Calculator Estimate continuous inverter capacity, surge rating, and DC input current from planned AC loads and headroom.
Wire Resistance Calculator Calculate conductor resistance, voltage drop, and heat loss from resistivity, length, cross-sectional area, and current.
Choose the right calculator
Use the appliance nameplate or a measured wattage and the rate from your utility bill. Duty cycles, standby use, seasonal operation, and tiered rates can change actual cost.
How these calculators are checked
Each tool shows its formula, assumptions, worked example, and limitations. We test default values, decimals, zero and invalid inputs, unit conversions, and rounding behavior. Learn more on How Our Calculators Work .
Important: Cost calculators do not size circuits or verify electrical safety. Wiring, panels, loads, and code compliance require qualified guidance.
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Reference and review
This category and its linked calculators were reviewed by the DIY Cost Tools editorial team on October 4, 2026. Additional tools will be added without changing the category URL.