Circuit Calculators
These circuit tools include a resistor calculator for LED series resistors and series-parallel networks, plus Zener diodes, 555 timers, LM317 regulators, admittance, and more.
Flyback Converter Calculator
This flyback converter calculator relates the output voltage, input voltage, duty cycle, and transformer turns ratio…
Open calculator CircuitElectrical Admittance Calculator
This admittance calculator finds the admittance Y — the reciprocal of impedance — from impedance, or…
Open calculator CircuitInstrumentation Amplifier Calculator
This instrumentation amplifier calculator finds the gain of the classic three-op-amp in-amp from the gain-setting resistor.…
Open calculator Circuit555 Timer Calculator
This 555 timer calculator covers both astable (oscillator) and monostable (one-shot) modes. Enter your resistor and…
Open calculator CircuitZener Diode Calculator
This zener diode calculator sizes the series resistor for a zener voltage regulator and checks the…
Open calculator CircuitMicrocontroller Time Delay Calculator
This microcontroller delay calculator finds the time a delay loop takes on an 8051 or PIC…
Open calculatorParallel Resistance Calculator
This parallel resistance calculator finds the equivalent resistance of two or more resistors wired in parallel.…
Open calculator CircuitLM317 Voltage Calculator
This LM317 voltage calculator finds the regulated output voltage from resistors R1 and R2, or the…
Open calculator CircuitLM317 Current Regulator Calculator
This LM317 current regulator calculator finds the resistor that sets a constant output current, using the…
Open calculator CircuitNE555 Timer Astable Calculator
This NE555 timer calculator finds the output frequency and duty cycle of a 555 astable oscillator…
Open calculator CircuitSeries and Parallel Resistance Calculator
This series and parallel resistance calculator finds the total (equivalent) resistance of a resistor network. Enter…
Open calculatorAbout Circuit Calculators
These circuit tools include a resistor calculator for LED series resistors and series-parallel networks, plus Zener diodes, 555 timers, LM317 regulators, admittance, and more. Pick a tool below for an instant result and its formula.
Component values decide whether a circuit works or fails. These tools apply the correct equation for each part and show a worked example so your design values are sound.
Calculators in this category
- Zener Diode Calculator
- LED Series Resistor Calculator
- LM317 Current Regulator Calculator
- LM317 Voltage Calculator
- 555 Timer Calculator
- NE555 Timer Astable Calculator
- Series and Parallel Resistance Calculator
- Parallel Resistance Calculator
- Electrical Admittance Calculator
- Flyback Converter Calculator
- Instrumentation Amplifier Calculator
- Microcontroller Time Delay Calculator
Frequently Asked Questions
What circuits can I calculate?
LED series resistor, Zener diode, 555 and NE555 timers, LM317 current and voltage, series-parallel resistance, admittance, flyback SMPS, and an instrumentation amplifier. Each tool covers one task.
Are these tools free to use?
Yes. Every calculator on this page is free, needs no signup, and works in your browser on mobile and desktop.
Do the tools give a worked example?
Yes. Each page states the formula, defines the component values, and includes a numeric example you can follow.