FREE TOOLS
Engineering Calculators
Interactive tools for electrical, electronic, mechanical and control engineering. Every calculator updates as you type and comes with the formula, a worked example, typical values and the mistakes to avoid.
555 Timer Astable
Calculate the frequency, period and duty cycle of an NE555 astable multivibrator from R1, R2 and C. Formulas, typical values table, worked example and free simulation.
Use calculator →Calculator555 Timer Monostable
Calculate the output pulse width of an NE555 monostable from R and C. Formula t = 1.1·R·C, typical values table, worked example and design tips.
Use calculator →CalculatorThree-Phase Power
Calculate active power, apparent power and line current in balanced three-phase systems with P = √3 · V · I · cos φ. Worked examples at 208 V, 400 V and 480 V, quick table and common mistakes.
Use calculator →CalculatorElectrical Power
Calculate electrical power in watts from voltage and current. Formulas P = V·I, P = I²R and P = V²/R with worked examples and energy use in kWh.
Use calculator →CalculatorAngular Velocity
Convert RPM to rad/s and back. Angular velocity formulas, RPM to rad/s conversion table, tangential speed, power from torque and worked examples.
Use calculator →CalculatorInductive Reactance
Calculate the inductive reactance of a coil with XL = 2πfL from frequency and inductance. Impedance of a real inductor, phase angle, typical values and a worked 60 Hz example.
Use calculator →CalculatorNon-Inverting Amplifier Gain
Calculate the gain of a non-inverting op-amp amplifier with G = 1 + Rf/Rg, the expected output and the gain in dB. Worked example, bandwidth and real-world limits.
Use calculator →CalculatorPID Parameter Converter
Convert PID parameters between parallel form (Kp, Ki, Kd) and standard ISA form (Kp, Ti, Td). Formulas, conversion table, Ziegler–Nichols example and tuning warnings.
Use calculator →CalculatorVoltage Divider
Calculate the output of a resistive voltage divider with Vout = Vin · R2 / (R1 + R2). Live visualization, design formulas, loading effect and a worked 12 V battery example.
Use calculator →CalculatorPower Factor
Calculate the power factor from active and apparent power and get the reactive power. Power triangle, typical values and a worked example of power factor correction with capacitors.
Use calculator →CalculatorOhm’s Law
Ohm’s law calculator: find voltage from current and resistance with V = I × R. All three forms of the formula, power, typical values and worked examples.
Use calculator →CalculatorLED Resistor
Calculate the series resistor an LED needs with R = (Vs − Vf) / I. Values for red, green, blue and white LEDs at 5 V and 12 V, LEDs in series, resistor power and common mistakes.
Use calculator →CalculatorResistor Color Code
Resistor color code calculator: convert 4-band color codes to ohms and resistor values to bands. Full color table (IEC 60062), 5- and 6-band resistors, common values and reading tips.
Use calculator →More calculators (in Spanish for now)
We are translating the rest of the collection. These tools already work in any language, because the numbers are the same; only the explanations are in Spanish:
How these calculators are built
Each result is computed in your browser with the same code used by our virtual labs and checked against hand calculations and worked examples. They are educational tools: for critical designs, verify against datasheets, your local electrical code and professional software.