General Electronics Calculators
21 free calculators with formulas and worked examples.
Ohm's law, voltage dividers, op-amp gain, RC time constants, transistor biasing, 555 timer, crystal load capacitance, and other fundamental electronics calculators.
Ohm's Law
Calculate voltage, current, resistance, and power using Ohm's Law. Enter any two values to solve for the remaining two quantities.
Color Code
Decode resistor color bands to resistance value and tolerance. Supports 4-band, 5-band, and 6-band resistors. Instant color band to ohms conversion.
RC Time Constant
Calculate RC circuit time constant τ, charge time to 63.2% and 99%, and −3dB cutoff frequency. Essential for filter and timing circuit design.
Series/Parallel R·C·L
Calculate the equivalent series and parallel combination of up to four resistors, capacitors, or inductors. Also computes the voltage divider ratio for two-resistor networks.
LC Resonance
Calculate the resonant frequency, characteristic impedance, Q factor, and bandwidth of a series or parallel LC tank circuit. Enter inductance, capacitance, and optional series resistance.
Op-Amp Gain
Calculate op-amp voltage gain, gain in dB, −3 dB bandwidth, and input impedance for inverting, non-inverting, and differential amplifier configurations.
Wire Gauge
Convert between AWG and mm², calculate wire current capacity, resistance, and voltage drop
Capacitor Energy
Calculate capacitor energy (E = 1/2·CV²), stored charge (Q = CV), and average charging current. Enter capacitance in μF and voltage — get energy in mJ, charge in mC, and power instantly.
Zener Diode
Calculate series resistor, power dissipation, and load current for zener diode voltage regulators
Inductor Energy
Calculate energy stored in an inductor, L/R time constant, and current rise time
BJT Bias Point
Calculate BJT voltage divider bias Q-point including collector current, base voltage, VCE, power dissipation, and operating region
MOSFET Operating Point
Calculate MOSFET drain current, saturation voltage, transconductance, and operating region (cutoff, triode, saturation) for NMOS transistors
Comparator Hysteresis
Calculate comparator hysteresis trip points for Schmitt trigger circuits, upper and lower threshold voltages, and design resistor values for a desired hysteresis percentage
555 Timer
Calculate 555 timer frequency, period, duty cycle, and pulse width for both astable oscillator and monostable one-shot configurations
Transistor Switch
Calculate BJT transistor switch parameters including load current, required base current, base resistor value, saturation check, and power dissipation
Current Mirror
Calculate current mirror output current, beta error, reference resistor, power consumption, and Widlar mirror resistor for analog IC and bias circuit design
Schmitt Trigger
Calculate non-inverting Schmitt trigger threshold voltages and hysteresis band for comparator circuits with positive feedback.
Crystal Load Cap
Calculate actual load capacitance seen by a crystal oscillator, estimate frequency error from spec, and find recommended external capacitor values.
Op-Amp Bandwidth
Calculate op-amp closed-loop -3dB bandwidth from the gain-bandwidth product (GBW), determine rise time, and verify phase margin.
LM317 Resistors
Calculate R2 resistor value for LM317/LM338 adjustable voltage regulator output voltage, with actual Vout and resistor power dissipation.
LDO Dropout
Calculate LDO minimum input voltage from dropout specification, determine power dissipation, and estimate efficiency at a given supply voltage.
About General Electronics Calculators
General electronics encompasses the foundational laws and components that underpin every circuit: resistors, capacitors, inductors, diodes, and transistors operating at frequencies where lumped-element models remain valid.
Ohm's law (V = IR) and its power corollary (P = IV = I²R = V²/R) are the starting point for every circuit analysis. Series and parallel resistor combinations, voltage dividers, and current mirrors build up to more complex topologies. The RC time constant (τ = RC) governs charging and discharging in timing circuits, filters, and debouncing networks. The 555 timer implements monostable and astable multivibrators using RC networks around two comparator thresholds.
Op-amp circuits are the backbone of analog signal conditioning. An inverting amplifier's gain is −R_f/R_in; a non-inverting amplifier's gain is 1 + R_f/R_in. Bandwidth degrades with gain (gain-bandwidth product is constant), so a high-gain stage at MHz frequencies requires careful compensation. Comparators with hysteresis (Schmitt triggers) add noise immunity to threshold detection, preventing chatter near the switching point.
Crystal load capacitance directly affects oscillator frequency: the crystal sees C_L = (C1·C2)/(C1+C2) + C_stray, and deviations from the specified load shift the oscillation frequency by hundreds of ppm — critical for UART, SPI, and USB timing accuracy. BJT and MOSFET biasing calculators set the quiescent operating point for linear amplification, ensuring sufficient headroom before saturation or cutoff.