Electricity Calculator

  • Flyback Converter Calculator
    Calculate flyback converter output voltage from input voltage, transformer turns ratio (Ns/Np), and duty cycle D using Vout = Vin × (Ns/Np) × D/(1−D).
  • Capacitive Transformerless Power Supply Calculator
    Calculate dropper capacitor reactance and available output current for a capacitive transformerless power supply from mains voltage, frequency and capacitance.
  • MOSFET Threshold Voltage Calculator
    Calculate the MOSFET threshold voltage Vth from flat-band voltage, Fermi potential, substrate doping, oxide capacitance and silicon permittivity.
  • Speaker Crossover Frequency Calculator
    Calculate first-order speaker crossover capacitor and inductor values from impedance and crossover frequency. Free 6 dB/octave passive crossover designer.
  • 555 Timer Calculator
    Calculate the output frequency, period, and duty cycle of a 555 timer in astable mode from R1, R2, and the capacitor value.
  • Magnetic Force Between Current-Carrying Wires Calculator
    Calculate the magnetic force per unit length and total force between two parallel current-carrying wires using F/L = μ₀·I₁·I₂/(2π·d).
  • Magnetic Force on a Current-Carrying Wire Calculator
    Calculate the magnetic force on a current-carrying wire using F = B × I × L × sin(θ). Enter flux density, current, length and angle to get force in newtons.
  • LED Resistor Calculator
    Calculate the correct series resistor for an LED from supply voltage, LED forward voltage and current. Get resistance in ohms plus power dissipation.
  • J-Pole Antenna Calculator
    Calculate J-pole antenna element lengths from frequency. Get the long 3/4-wave radiator and 1/4-wave matching stub in feet, inches and cm.
  • Ideal Transformer Calculator
    Compute secondary voltage, turns ratio and secondary current for an ideal transformer using Vp/Vs = Np/Ns = Is/Ip. Free online calculator.
  • Low Pass Filter Calculator
    Calculate the cutoff frequency of a passive RC low pass filter from resistance and capacitance. Get fc, time constant and angular frequency instantly.
  • Inductors in Parallel Calculator
    Calculate total inductance of up to 4 inductors connected in parallel using 1/Lt = 1/L1 + 1/L2 + ... Fast, accurate, free online tool.
  • Inverting Buck-Boost Converter Calculator
    Calculate the negative output voltage of an inverting buck-boost converter from input voltage and duty cycle using Vout = −Vin × D/(1−D).
  • Inductors in Series Calculator
    Calculate total inductance of inductors connected in series. Just add the values: L_total = L1 + L2 + ... + Ln. Results in H, mH and µH.
  • Capacitors in Series Calculator
    Calculate the total capacitance of up to four capacitors wired in series using 1/Ct = 1/C1 + 1/C2 + ... Free, instant, accurate.
  • Inductor Energy Storage Calculator
    Calculate the energy stored in an inductor's magnetic field from its inductance and current using E = ½ × L × I². Fast, accurate, free.
  • High Pass Filter Calculator
    Calculate the cutoff frequency of a first-order RC high-pass filter from resistance and capacitance using fc = 1 / (2πRC).
  • Buck Converter Calculator
    Calculate buck (step-down) converter output voltage from input voltage and duty cycle, plus inductor ripple current and recommended inductance.
  • Helical Coil Inductance Calculator
    Calculate the inductance of a helical (solenoid) coil from turns, radius and length using L = μ₀N²A/l. Get results in µH, mH and H instantly.
  • Generator Power Calculator
    Calculate generator power output in kW, kVA and HP from voltage, current and power factor for single-phase or three-phase systems.
  • Dipole Antenna Calculator
    Calculate the total and per-leg length of a half-wave dipole antenna from frequency in MHz, in meters and feet. Free, instant, accurate.
  • Skin Depth Calculator
    Calculate the skin depth of a conductor from frequency, conductivity, and permeability. Find how deep AC current penetrates in copper, aluminum and more.
  • Current Divider Calculator
    Calculate the current through each resistor in a parallel current divider. Enter total current and two resistor values to get I through R1 and R2.
  • Capacitor Charge Time Calculator
    Calculate capacitor charging voltage over time in an RC circuit. Enter supply voltage, resistance, capacitance and time to get V(t) and time constant τ.

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