Electricity

These tools help with circuit design and with reading the markings on components. You can apply Ohm’s law to find voltage, current, resistance, or power, combine resistors in series and parallel, work out an RC time constant or an LC resonant frequency, and convert both ways between resistor and inductor colour bands or ceramic capacitor and SMD resistor number codes.

Ohm's Law Calculator (Voltage, Current, Resistance)

Use Ohm's law V=IR to calculate any one of voltage, current, or resistance from the other two values. Power (W) is calculated at the same time.

Resistor Color Code Calculator (Color to Value & Value to Color)

Calculate resistance and tolerance from a resistor's color code (4-band or 5-band). You can also enter a resistance value to find the matching band colors.

Series & Parallel Resistor Calculator (Total Resistance)

Calculate the total resistance of multiple resistors connected in series or parallel. Supports Ω, kΩ, and MΩ units, and lets you freely add or remove resistors.

Ceramic Capacitor Code Converter (Code to Capacitance & Capacitance to Code)

Decode a 3-digit ceramic capacitor code like "104" into pF, nF, and µF instantly, or convert a capacitance back into the standard code. Includes a tolerance letter table.

Free LC Resonant Frequency Calculator | Inductor-Capacitor Circuit

Free calculator for LC resonant circuits made of an inductor (L) and capacitor (C). Solve for frequency, inductance, or capacitance from the other two values, plus characteristic impedance.

Inductor (Coil) Color Code Calculator (Colors → Inductance & Inductance → Colors)

Calculate the inductance and tolerance of a small inductor (coil) from its 3 or 4 color bands, shown in µH, mH, and H. You can also enter an inductance value to look up the matching color bands.

RC Circuit Time Constant Calculator (with Charge/Discharge Graph)

Calculate the time constant τ = R × C of an RC circuit (a resistor R and capacitor C in series). See the charging and discharging curves on a graph, plus the time to reach 63.2% charge and the practical "fully charged" t...

SMD Resistor Code Calculator (3-Digit, 4-Digit & EIA-96)

Convert the numeric marking printed on a surface-mount (SMD) chip resistor into a resistance value. Supports 3-digit codes, 4-digit codes (precision resistors), and EIA-96 codes (2 digits plus a letter), with the format...