Electronics Calculators
Seven calculators for the arithmetic that comes up on every bench. Nothing to install, nothing to sign up for, and every answer links to the parts it implies.
Resistor Colour Code Calculator
Read a resistor value from its bands, with tolerance and the guaranteed range.
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Ohm's Law Calculator
Enter any two of voltage, current, resistance and power to get the other two.
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Voltage Divider Calculator
Output voltage from two resistors, plus the current the divider always draws.
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Resistor in Series Calculator
Add resistances end to end to reach a value you do not have in the drawer.
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Resistor in Parallel Calculator
Combined resistance side by side, always lower than the smallest one.
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LED Resistor Calculator
Size the series resistor for an LED, with wattage and the nearest stocked value.
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Battery Runtime Calculator
How long a battery lasts at a given draw, allowing for unusable capacity.
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Capacitor Code Calculator
Turn a printed three digit code into pF, nF and uF, with what the tolerance letter means.
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Battery Pack Calculator
Series and parallel cells into pack voltage, capacity, energy and the right charge voltage.
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Stepper Motor Calculator
Steps per millimetre for a leadscrew or belt, and the travel speed a given RPM gives.
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NTC Thermistor Calculator
Convert a thermistor resistance to a temperature using the B parameter equation.
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RC Filter Calculator
Time constant, cutoff frequency and settling time for a resistor and capacitor pair.
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555 Timer Calculator
Frequency, duty cycle and pulse width for a 555 in astable or monostable mode.
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LED Strip Power Calculator
Current, wattage and the supply an LED strip actually needs, with headroom.
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These run entirely in your browser. Nothing you type is sent anywhere or stored.