More Than a Calculators
Electrical & Electronics Calculators
Calculate voltage, current, resistance, power, filters, circuits, and electrical conversions using fast and practical calculators.
Basic Electrical Calculators
Voltage, current, resistance and Ohm’s law.
Ohm’s Law Calculator
Solve for voltage, current, resistance or power.
Current Calculator
Current from voltage and resistance, or from power and voltage.
Amps to Volts
Voltage from current and resistance or power.
Volts to Amps
Current from voltage and resistance or power.
Volts to Watts
Power from voltage and current, DC or AC.
Watts to Ohms
Resistance from power and voltage or current.
Joules to Volts
Voltage from energy and charge in coulombs.
Filters & Resonance
RC filters and resonance calculators.
RC Time Constant
Time constant τ = RC and charge times to 50, 63, 90 and 99%.
RC Low Pass Filter
Cutoff frequency and gain of a first-order RC low-pass filter.
RC High Pass Filter
Cutoff frequency, gain and phase of an RC high-pass filter.
LC Resonant Frequency
Resonant frequency of a series or parallel LC circuit.
Tank Circuit Resonance
Parallel LC tank resonance for oscillators and RF tuning.
Rise Time to Bandwidth
Bandwidth from 10–90% rise time using BW = 0.35 / tr.
Electrical Converters
Electrical unit conversions.
Popular Electrical Calculators
Most used calculators.
Electrical Calculators FAQ
Quick answers.
Which calculator should I use first?
Are calculators accurate?
Are they free?
More electrical calculators
Further tools in this category that were not listed above.
Current Divider Calculator
Branch currents and equivalent resistance of two parallel resistors.
BJT Biasing Network Calculator
Q-point of a voltage-divider biased BJT stage.
BJT Beta Calculator
Transistor current gain β from collector and base current.
Power Dissipation in Resistor Calculator
Watts a resistor turns into heat, and the rating it needs.
MOSFET Gate Charge Calculator
Gate drive current and switching loss from gate charge.
Inductor Energy Calculator
Energy stored in an inductor from inductance and current.
Ripple Voltage Calculator
Ripple on a rectifier smoothing capacitor from load and frequency.
Watts to kWh Calculator
Energy in kWh from power and hours of use.
Solar Panel Watts to Amps Converter
Panel current from rated watts and system voltage.
BTU to Tons of Cooling Converter
Convert BTU/hr to tons of refrigeration and back.
COP to Kw Calculator
Heat pump or chiller output from COP and electrical input.
Transformer Turns Ratio Calculator
Turns ratio, secondary voltage and current of a transformer.
Capacitive Reactance Calculator
Reactance of a capacitor at a given frequency.
Inductive Reactance Calculator
Reactance of an inductor at a given frequency.
Capacitor Charge Time Calculator
Time for a capacitor to reach a chosen voltage through a resistor.
Voltage Divider Calculator
Output voltage of two series resistors, and resistor values for a target.
Lumens to Watts Calculator
Wattage needed for a lumen output by lamp type.
BTU to kWh Calculator
Convert BTU to kilowatt-hours and back.
Frequency to Wavelength Calculator
Wavelength from frequency in air, cable or another medium.
Battery Life Calculator
Runtime from battery capacity and load current.
LED Resistor Calculator
Series resistor value and wattage for an LED.
Power Factor Calculator
Power factor, real and reactive power from an AC load.
Inductance Calculator
Inductance of an air-core coil from turns and dimensions.
Capacitor Discharge Calculator
Voltage left on a capacitor after discharging for a set time.
Capacitor Charge Calculator
Charge and energy stored in a capacitor at a given voltage.
Voltage Calculator
Voltage from current and resistance or from power.
Solar Panel Calculator
Number of panels needed for a daily energy target.
Appliance Energy Calculator
Yearly energy and cost of running an appliance.
Electricity Bill Calculator
Estimated bill from kWh used and your tariff.
Electric Power Cost Calculator
Cost of running a load for a given time at your rate.
Wire Size Calculator
Conductor gauge for a current, distance and allowed voltage drop.
Resistors in Parallel Calculator
Equivalent resistance of resistors in parallel.
Resistors in Series Calculator
Equivalent resistance of resistors in series.
Resistor Color Code Calculator
Read resistor value and tolerance from colour bands.
Ohms to Watts Calculator
Power from resistance and voltage or current.
Watts to Volts Calculator
Voltage from power and current or resistance.
Amps to Watts Calculator
Power from current and voltage, single or three phase.
Watts to Amps Calculator
Current from power and voltage, single or three phase.
Resistance Calculator
Resistance from any two of voltage, current and power.
Voltage Drop Calculator
Voltage lost along a cable run for a given load and gauge.
What the electrical and electronics calculators cover
This hub gathers every electrical tool on More Than A Calculators, from the basic Ohm’s law relationships used in every circuit to filter design, transistor biasing and the cost of running an appliance. Each calculator runs in your browser, states the formula it applies, and expects SI units unless the field says otherwise. The tools fall into six groups.
Ohm’s law and power
Start with the Ohm’s law calculator, which solves for any of voltage, current, resistance and power. The single-purpose versions, resistance, current, voltage, watts to amps and amps to watts, do the same job with fewer fields. The power dissipation calculator tells you what wattage rating a resistor needs, and the series and parallel resistor calculators combine values.
Circuits and components
The voltage divider and current divider calculators split a supply between resistors, and the loaded voltage divider calculator shows how much the output sags when something is connected. The LED resistor calculator picks the series resistor for an LED, the colour code calculator reads a resistor’s bands, and the capacitor charge, charge time, discharge and inductor energy calculators cover energy storage. Transistor stages are handled by the BJT biasing calculator, BJT beta calculator and MOSFET gate charge calculator.
Filters, timing and resonance
The RC time constant calculator is the starting point for anything involving a resistor and a capacitor. The low-pass and high-pass filter calculators give cutoff frequency and gain, the capacitive and inductive reactance calculators give impedance at a frequency, and the LC resonant frequency and tank circuit calculators cover tuned circuits. The rise time to bandwidth calculator links edge speed to the bandwidth a scope or channel needs.
AC power and mains
The power factor calculator separates real, reactive and apparent power. The transformer turns ratio calculator sizes windings, the ripple voltage calculator sizes a rectifier’s smoothing capacitor, and the wire size and voltage drop calculators keep cable runs within limits.
Energy, cost and solar
The watts to kWh calculator turns a load and running time into energy. The appliance energy, electricity bill and power cost calculators put a price on that energy, and the solar panel calculator and watts to amps converter size a photovoltaic array. The battery life calculator estimates runtime from capacity and load.
Converters
The dBm to mW and dB to ratio converters handle logarithmic units, and the frequency to wavelength calculator relates the two for antennas and cables. Unit converters for inductance, capacitance, frequency, resistivity and conductivity round out the set.
Tips for reliable results
- Enter base units. Capacitors are marked in µF, nF and pF, but the calculators expect farads: 100 nF is 1e-7. Inductors are the same in henries.
- Use RMS for AC. Mains is 230 V or 120 V RMS; the peak is 1.41 times higher and belongs only in insulation and rectifier calculations.
- Respect component ratings. A calculated 0.4 W dissipation needs a 1 W resistor in practice, and an electrolytic capacitor needs a voltage rating well above the supply.
- Check units on the result. Currents come out in amperes, so 0.02 A is 20 mA.
A typical design chain
To run an LED from a 12 V supply, the LED resistor calculator gives the series resistor and the power dissipation calculator confirms a quarter-watt part is enough. To smooth the same supply from a rectifier, the ripple voltage calculator sizes the capacitor, the RC time constant calculator predicts how long it takes to charge, and the capacitor discharge calculator shows how long the output holds up when power is cut. Each result page links to the next tool, so a small power supply can be worked through in minutes.
These calculators are for study, hobby projects and preliminary design. Mains wiring must follow the applicable electrical code and be checked by a qualified electrician.