20 tools
Electronics & PCB Tools
Twenty calculators for bench and board work: resistor, SMD, capacitor and inductor codes, LED and divider design, RC, RL and LC maths, 555 and op-amp circuits, PCB trace and via sizing, decibels, SNR and ADC resolution.
About these tools
These are the small calculations that interrupt a build: what is this marking worth, what resistor does this LED need, where does this filter roll off, how wide must this track be. Each one shows the formula and the assumptions rather than just a number, so you can sanity-check it against a datasheet before you cut copper.
The PCB tools use the IPC-2221 curve fit, which is a deliberately conservative generic rule derived from old test data - it knows nothing about your copper pour, your airflow or the parts sitting next to the track. Where a figure depends on a real component, the page asks you for the datasheet value instead of inventing one. Everything runs locally in your browser.
Popular tasks
All Electronics & PCB Tools
- Resistor Color Code Calculator Read a resistor from its colour bands or work backwards from a value: resistance, tolerance, temperature coefficient, the nearest E-series preferred value and the band pattern drawn for you.
- SMD Resistor Code Calculator Decode surface-mount resistor markings in all the common systems - three digit, four digit, the R notation for fractions and EIA-96 code plus multiplier letter - and convert any value back into its marking.
- Capacitor Code Calculator Decode ceramic and film capacitor markings: the three-digit picofarad code, the tolerance letter, the voltage code and dielectric classes such as X7R and C0G, with the value converted between pF, nF and uF.
- Inductor Color Code Calculator Read moulded inductor colour bands or numeric markings into an inductance value with tolerance, convert between nH, uH and mH, and see the reactance the part presents at a frequency you choose.
- LED Series Resistor Calculator Choose the series resistor for one LED or a string: the exact value from supply, forward voltage and current, the nearest preferred value, the current you actually get and the power each part dissipates.
- Voltage Divider Calculator Calculate divider output voltage, current and dissipation, see how much a load resistance shifts the output, and get the closest E12, E24 or E96 resistor pair for the ratio you want.
- RC Time Constant Calculator Work out the RC time constant, the time to reach any percentage of the final voltage, the charge and discharge curve, and the first-order low-pass or high-pass cutoff frequency with phase shift.
- RL Time Constant Calculator Calculate the RL time constant, current rise and decay against time, the energy stored in the inductor and the voltage spike an abrupt switch-off produces, with flyback clamping worked through.
- LC Resonance Calculator Find the resonant frequency of an LC pair, or the inductance or capacitance needed for a target frequency, with Q factor, bandwidth, impedance at resonance and the reactance of each part.
- Operational Amplifier Gain Calculator Work out op-amp gain for inverting, non-inverting, buffer, summing and difference configurations, in volts per volt and decibels, with the closed-loop bandwidth the gain-bandwidth product allows.
- 555 Timer Calculator Design a 555 circuit: astable frequency, high and low times and duty cycle from R1, R2 and C, monostable pulse width, the component values for a target frequency, and the duty cycle limits of the basic circuit.
- Transistor Bias Calculator Bias a bipolar transistor as a switch or a small-signal amplifier: base resistor for guaranteed saturation with an overdrive factor, collector current, the quiescent point of a divider bias stage and the power in each part.
- MOSFET Gate Resistor Calculator Choose a gate resistor from total gate charge and driver voltage: peak gate current, rise and fall time, switching and conduction loss at your frequency, and the trade-off between speed and ringing.
- PCB Trace Width Calculator Size a PCB track with the IPC-2221 formula: the width needed for a current and temperature rise on an internal or external layer, the resistance and volt drop of the run, and the power it turns into heat.
- PCB Via Current Calculator Work out how much current a via can carry: the copper barrel cross-section from drill diameter and plating thickness, the equivalent trace width, the resistance of the barrel and how many vias a net needs.
- Microstrip Impedance Calculator Estimate the characteristic impedance of a microstrip or stripline track from width, dielectric height, copper thickness and Er, with effective permittivity, propagation delay per unit length and the width for a target impedance.
- Decibel Converter Convert between decibel scales and absolute quantities: dB from a power or voltage ratio, dBm to watts, dBW, dBu and dBV with the reference each one uses, and gain chains added up in dB.
- Signal-to-Noise Ratio Calculator Calculate signal-to-noise ratio from signal and noise levels in volts, watts or dBm, convert between SNR, SINAD, THD+N and effective number of bits, and estimate thermal noise floor for a bandwidth and temperature.
- ADC Resolution Calculator Work out what an analogue-to-digital converter can actually resolve: LSB step in volts, quantisation error, ideal SNR for the bit depth, the code for a given input and the Nyquist rate and data volume for your sampling.
- Battery Series-Parallel Calculator Configure a battery pack: cells in series and parallel, nominal and charge voltage, capacity in Ah and Wh, C-rate limits for charge and discharge, pack current at a load and the cable size that current needs.
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