Calculation Workbench (Beta)
Everyday electronics arithmetic answered in the page, with worked steps and no server round trip.
What it does
Design work involves a lot of small sums: what resistor sets this divider, how wide a track has to be, what frequency a coil and capacitor resonate at. Each one is easy and each one interrupts what you were doing. The workbench keeps the common ones on a single page, so there is no spreadsheet to open and no bookmark to hunt for.
Choose the calculation, enter the values you know, then press Calculate Values. The result appears with the worked steps behind it, so the answer can be checked rather than simply trusted. Everything runs in the page, so nothing entered here is transmitted anywhere.
Key features
- Ohm's law and electrical power, filling in the missing value from any two knowns
- Resistors and capacitors in series and parallel, up to five at a time
- 4-band and 5-band resistor colour code decoding
- Multi-resistor voltage dividers with junction voltages, current, transfer ratios and power dissipation
- LED series resistor sizing from supply, forward voltage and target current
- PCB track width from IPC-2221 current, temperature rise and copper weight
- Wavelength, half and quarter wavelength from frequency and velocity factor
- LC resonance plus RLC band-pass bandwidth and cutoff frequencies
- Calculate Values button with worked steps for every result
- Save results to a browser-local scratch pad stored in local storage
- Selectable SI units, with all calculation in the browser
Units are selectable rather than typed: every input has an SI unit choice, so a resistance can go in as ohms or kilo-ohms and a capacitance as farads, microfarads or nanofarads. Pressing Calculate Values runs the solver and shows the result alongside the steps that produced it.
How the calculations work
Each panel is a real solver rather than a lookup table. The inputs are converted to base units, the relationship is rearranged for the value you asked for, and the result is formatted back into a readable unit with the working shown line by line.
Ohm's law and electrical power
Voltage, current and resistance share one relationship, and power sits alongside it. The Ohm's law solver fills in the missing voltage, current or resistance from any two you know; the power solver works from any two of power, voltage, current and resistance. Both are available in the workbench, so the answer to a supply question and the dissipation behind it are easy to compare.
Resistor and capacitor networks
Series and parallel combinations of up to five resistors or five capacitors, solved as one network rather than a pair at a time. A separate decoder reads a 4-band or 5-band resistor colour code back to a value when the part is already in your hand.
Voltage dividers
A divider of several resistors, not just two. The solver returns the junction voltages down the chain, the current it draws, the transfer ratios and the power dissipated in each resistor, with the calculation laid out step by step.
LED series resistor
Set the supply voltage, the LED forward voltage and the current you want, and the solver returns the series resistor. It is usually the first calculation behind a new circuit, and it is easy to get wrong by a decade when a datasheet quotes milliamps.
LC and RLC resonance
The LC form returns the resonant frequency, the angular frequency and the reactance at resonance. The RLC band-pass form returns the bandwidth and the two cutoff frequencies, which is the pair you need when the question is whether a filter will pass the signal you care about.
Wavelength
Full, half and quarter wavelength from a frequency and a velocity factor. That is the quick way to size an antenna element, or to check whether a run of cable or a trace is accidentally resonant at the frequency you are working with.
PCB track width
Track width from a target current, an allowable temperature rise and a copper weight or thickness, following the IPC-2221 charts rather than a rule of thumb. It is the practical way to sanity-check a track before a layout is committed.
Beta limitations
These are ideal-value calculations. Resistor tolerance, temperature coefficients, capacitor dielectric behaviour, parasitics and layout effects are not modelled, and a formula that is right for a first-order estimate is not a substitute for simulation or measurement on a real circuit.
The track-width result in particular follows the IPC-2221 charts as an engineering estimate, not a certification. It is only as good as the current, temperature rise and copper weight or thickness you give it, so confirm it against your fabrication house's requirements and the standard before relying on it.
Privacy: it runs in your browser
Every solver is client-side code. The component values, frequencies and currents you enter are never sent to a server and are not retained by Protoworks. Results you choose to save go into a scratch pad held in this browser's local storage, on this device, and stay there until you remove them from the panel or clear the browser's site data. Nothing is added to that scratch pad unless you press Save, and a reload otherwise starts from a clean set of inputs.
Who it suits
- Electronics engineers who want the routine sums in one place instead of scattered bookmarks.
- Firmware and software developers working alongside hardware who need a quick, trustworthy answer.
- Students and hobbyists learning why a value behaves the way it does, with the steps laid out beside the result.
- Anyone reviewing a schematic away from their usual bench and toolchain.
When a calculation turns into a circuit, a PCB layout or firmware to drive it, that is the work I take on: design files, embedded code and the documentation needed to build from them.
Other demos and tools
Gerber Viewer
Open a Gerber and Excellon drill archive in your browser and check PCB layers before fabrication.
G-Code Viewer
Preview a 3D printing G-code file in 3D before you print, step through the toolpath and keep the file on your device.
QR Code Creator
Generate a styled QR code in your browser with your own colours, logo and error-correction level, then export PNG or SVG.
The full set is on Demos & Tools, and the wider software catalogue, including portals and APIs, is on the software solutions page.
Questions
Which calculations are included?
Ohm's law and electrical power; resistors and capacitors in series and parallel, up to five at a time; 4-band and 5-band resistor colour codes; multi-resistor voltage dividers with junction voltages, current, transfer ratios and power dissipation; LED series resistors; PCB track width from IPC-2221; wavelength, half and quarter wavelength from a frequency and velocity factor; and LC resonance together with RLC band-pass bandwidth and cutoff frequencies.
Are my values sent anywhere?
No. The solvers run client-side in your browser, so design values are not transmitted to a server or stored by Protoworks. If you press Save, the entry is kept in this browser's local storage, in a scratch pad on the same device, until you remove it.
How do I get a result?
Choose the calculation, enter your values, then press Calculate Values. The result appears with the worked steps that produced it, so you can set every input before anything is calculated and check the answer afterwards.
Can I enter values in different units?
Yes. Each input has a selectable SI unit, so a resistance can be entered in ohms or kilo-ohms and a capacitance in farads, microfarads or nanofarads. The result is shown in a readable unit with the worked steps beside it.
Is the trace-width result final?
No. Track width is an estimate based on IPC-2221, calculated from the target current, the allowable temperature rise and the copper weight or thickness you enter. Treat it as a starting point and confirm it against your fabrication house's requirements before committing a design.
Need the design behind the numbers?
I design circuits, custom PCBs and embedded firmware, and hand over the design files and documentation. If you want a second opinion on a circuit or a track-width decision, a short conversation is usually enough to tell whether it needs advice or real engineering time.