Free Online Electronics Calculators
20 essential interactive calculators for electronics engineers, students and hobbyists from Ohm’s law to PCB trace width. Instant results, formula transparency, and a step-by-step usage guide with every tool. No signup required.
Ohm's Law Calculator
Ohm’s Law defines the fundamental relationship between voltage (V), current (I), and resistance (R) in any electrical ci
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Resistor Color Code
Through-hole resistors use colored bands painted on the body to indicate their resistance value.
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LED Resistor Calculator
Every LED needs a current-limiting resistor to prevent it from drawing too much current and burning out.
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Voltage Divider Calculator
A voltage divider uses two series resistors to produce an output voltage that is a fraction of the input voltage.
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555 Timer Astable Mode
In astable mode, the NE555 timer generates a continuous square wave output without any external trigger.
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555 Timer Monostable Mode
In monostable (one-shot) mode, the 555 timer outputs a single HIGH pulse of a precisely defined duration when triggered.
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RC Time Constant
The RC time constant (τ = tau) defines how fast a capacitor charges or discharges through a resistor.
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Capacitor Code (3-Digit)
Ceramic and film capacitors often have a 3-digit code printed on them instead of the full value.
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Coil Inductance
Calculate the inductance of a single-layer air core coil using Wheeler’s approximation formula.
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SMD Resistor Code
Surface Mount Device (SMD) resistors use numeric codes instead of color bands.
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Electrical Power Calculator
Calculate electrical power using the three standard power formulas: P=V×I, P=I²×R, and P=V²/R.
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Battery Life Calculator
Estimate how long a battery will last based on its capacity (mAh) and the circuit’s average current draw (mA).
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LM317 Regulator
The LM317 is one of the most popular adjustable positive voltage regulators in electronics, capable of supplying 1.25V t
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Wire Gauge (AWG)
Select an American Wire Gauge (AWG) size to see its diameter, maximum current capacity for chassis wiring, and resistanc
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PCB Trace Width
Calculate the minimum PCB copper trace width required to safely carry a specified current without exceeding a given temp
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Op-Amp Gain Calculator
Calculate the voltage gain of standard operational amplifier configurations.
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Frequency & Wavelength
Convert between frequency and wavelength for electromagnetic waves using the speed of light constant.
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Capacitive Reactance
Capacitive reactance is the opposition a capacitor presents to alternating current (AC).
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Inductive Reactance
Inductive reactance is the opposition an inductor presents to alternating current (AC).
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Transformer Turns Ratio
Calculate the turns ratio of a transformer from primary and secondary voltages.
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