Electronics tools

Online electronics calculators

Practical browser-based calculators for common electronics design tasks, from Ohm’s law and LED resistors to 555 timers and op-amp gain.

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Calculate VOUT, VIN, R1 or R2 for a two-resistor potential divider.

Calculate voltage, current or resistance using Ohm’s law.

Calculate the LED series resistor, supply voltage, forward voltage or current.

Calculate timing values, frequency, duty cycle, on-time and off-time for a 555 astable.

Calculate pulse time, timing resistance or timing capacitance for a 555 monostable.

Calculate closed-loop gain or either feedback resistance for a non-inverting op-amp stage.

Calculate closed-loop gain or either resistance for a standard inverting op-amp stage.

Built to be useful

Each calculator is focused on one circuit or design problem, with the formula and circuit context kept close to the result.

No generic equation solver. Each tool is built around a real electronics circuit and the quantities engineers actually need.

Inputs, outputs and diagrams are arranged around the circuit so the numbers remain connected to what you are designing.

Use the calculators on desktop, tablet or mobile without downloading software or creating an account.

Need the theory too?

Use the guides to identify parts, build circuits and improve soldering technique, then return here when you need to calculate component values.