Calculators

Electronics calculators

Small, focused calculators for the arithmetic that comes up while you design. Each one runs entirely in your browser and updates as you type — and every one has a matching circuit you can open in the simulator to check the answer for real.

Fundamentals

Ohm's law calculator

Enter any two of voltage, current, resistance and power — get the other two.

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Analog

Voltage divider calculator

Two resistors and an input voltage in — the output voltage and divider current out.

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LED resistor calculator

Size the series resistor for an LED from supply voltage, forward voltage and target current.

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Dynamics

RC time constant calculator

Resistance and capacitance in — the time constant and charge/discharge times out.

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Reference

Resistor color code calculator

Pick the four bands on a resistor and read off its value and tolerance.

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Timers

555 timer calculator (astable)

Work out the frequency, period and duty cycle of a 555 in astable mode from R1, R2 and C.

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