Choosing a Tool

Circuit simulator vs. PCB and electrical CAD: which one do you need?

Published September 9, 2026 · By Britt at CircuitSim · 10 min read

If you have used KiCad, EasyEDA, or SkyCAD, a fair question about CircuitSim is what a simulator is for. Those tools draw circuits too, and two of them run simulations. The short answer is that CAD tools produce a document you hand to someone who builds the thing, and a simulator produces a measurement of how the thing behaves. The only piece they share is the schematic. Below is what each category is built to output, what the simulators inside KiCad and EasyEDA do, where CircuitSim fits next to tools we think are good at their jobs, and a separate section for the case where the goal is a course or learning electronics, because there the comparison includes Tinkercad Circuits and the answer is different.

Short answer. Electrical CAD such as SkyCAD, AutoCAD Electrical, and EPLAN produces wiring diagrams, panel layouts, and parts lists for a control cabinet or a machine. PCB design software such as KiCad, EasyEDA, and Altium produces a board layout and the Gerber files a fab needs, and KiCad and EasyEDA both bundle a simulator. A circuit simulator such as CircuitSim, LTspice, or the Falstad applet produces voltages, currents, waveforms, and frequency responses, and does not produce a board or a drawing package. If your project ends in hardware, you will use one of the first two. If you need to know what the circuit does before you commit to hardware, you want the third. If you are teaching or learning circuits, you also want the third, and the choice within it is between a teaching tool like Tinkercad and a SPICE simulator like CircuitSim, which comes down to how far the course goes.

Three tools, three outputs

The clearest way to tell these categories apart is to ask what file leaves the program at the end of the job.

Electrical CAD ends in a drawing set. SkyCAD describes itself as electrical schematic software for automation factories and OEMs, and its feature list is wire and component numbering, cross-references, parts lists and BOM management, panel layout, wire harness management, and configuration management for product variants. Those features describe the job: a set of drawings a panel builder or an electrician can work from, with every wire labeled and every part on a list. Simulation is not part of it, and SkyCAD's feature list does not mention one. The schematic is a construction document, and in this category the components on it are contactors, relays, breakers, and terminals rather than transistors.

PCB design ends in Gerbers. KiCad and EasyEDA start with schematic capture, but the schematic exists to drive a netlist into a board layout. The output is a set of Gerber and drill files, a pick-and-place file, and a BOM, and EasyEDA goes one step further by ordering the board from JLCPCB inside the same tab. Both include a simulator, which is where the overlap with a tool like ours comes from.

A circuit simulator ends in a number or a plot. CircuitSim has a schematic editor because you need one to describe the circuit, but nothing about the drawing is meant to be manufactured. The output is a DC operating point, a transient waveform, an AC sweep showing gain and phase against frequency, a DC sweep, a parameter sweep, or a live interactive run where you turn a potentiometer and watch the output move. When the answer is a gain, a corner frequency, a bias point, or a settling time, this is the tool that produces it.

What the simulator inside a PCB tool does

KiCad and EasyEDA both simulate. The question is what each bundled simulator covers and where it stops.

KiCad's simulator is ngspice, running inside the schematic editor. It offers operating point, DC transfer, AC sweep, and transient analysis, plus a custom mode for writing your own SPICE command, and a probe tool for picking nets and pins to plot. Because it is ngspice, it reads models in the SPICE, LTspice, PSpice, and HSPICE dialects, and the generic resistors, capacitors, diodes, and transistors simulate with ngspice's built-in models. The KiCad 10 release post from March 20, 2026 mentions improvements to the simulator plotting tools and nothing else about simulation. The limit is stated plainly on KiCad's own page: KiCad does not bundle any third-party SPICE libraries. A specific manufacturer part, a TL072 or an IRF540, needs its model downloaded from the manufacturer and attached to the symbol before it will simulate as that part.

EasyEDA has two editions with different simulators. EasyEDA Standard's simulation FAQ says the feature is powered by LTspice, that it supports simple schematics only, that it has very few simulation models, and, in its own words, that EasyEDA's main target is schematic and PCB, not simulation. EasyEDA Pro added simulation in version 3.2 with two engines, an entry-level real-time one called Simulide and ngspice for transient and AC analysis.

What a standalone simulator adds is a parts library where the components already carry their models, more analysis types, and the probes, sweeps, and export needed when you change a value, run, read the result, and change it again many times in a session. A bundled simulator covers the sanity check before layout, and for a lot of board projects that is all the simulation the project needs.

Where CircuitSim sits

CircuitSim runs ngspice compiled to WebAssembly, in the browser tab, with no install. If you have used the simulator in KiCad, the engine and the analysis names will be familiar. The differences are around the engine.

Parts arrive with their models. The library has 5,000+ components, and a named part such as a TL072 simulates with the manufacturer's model when you place it, with no .lib file to find and bind to a symbol. When a part is missing, the custom component studio takes SPICE model text pasted from a datasheet, and it can import a KiCad symbol for the drawing side, so a symbol you already have in KiCad can carry a model in CircuitSim.

Seven analyses and a live mode. Interactive, interactive operating point, transient, AC sweep, and DC operating point come with the free Basic plan. Standard, at $2.99 per month or $30 per year, adds DC sweep, with a nested second source for transistor curve families, and parameter sweep over DC, AC, or transient. Interactive mode streams the simulation while you work, so a switch, a potentiometer, or a value change shows up in the chart as you make it.

Around the engine sit the probes and readouts: voltage probes with a differential reference, current probes, digital lanes for logic, expression outputs for derived quantities such as power or gain, Bode charts with separate magnitude and phase, an oscilloscope-style triggered chart in interactive mode, and a table with minimum, maximum, and average per trace that exports to CSV or XLSX for a report. For a class, group licenses give each student a private seat behind a link, with no sign-up and no email collected. CircuitSim for schools covers how seats work.

What CircuitSim does not do. There is no PCB layout, no Gerber export, and no fabrication ordering, and none of those are in development. There is no wiring diagram or panel drawing output either. It does not run offline. The free Basic plan caps a circuit at five components, not counting probes and ground. If your project ends in a board or a cabinet, you will finish it in another tool.

	Electrical CAD SkyCAD, AutoCAD Electrical, EPLAN	PCB design KiCad, EasyEDA, Altium	Circuit simulator CircuitSim
What leaves the tool	Wiring diagrams, panel layouts, BOM, wire lists	Board layout, Gerber and drill files, BOM, pick-and-place	Waveforms, sweeps, operating points, CSV and XLSX data
Typical components	Contactors, relays, breakers, terminals	Any part with a footprint	Any part with a SPICE model
Simulation	Not a feature of the category; SkyCAD lists none	Bundled: KiCad runs ngspice with four analyses plus a custom mode and no bundled model library; EasyEDA Standard is LTspice-based with few models; EasyEDA Pro adds Simulide and ngspice	The whole product: seven analyses, live interactive mode, 5,000+ parts, named parts with manufacturer models
PCB layout	No (panel layout, not boards)	Yes	No
Runs in a browser	SkyCAD is a desktop install	EasyEDA yes; KiCad is a desktop install	Yes, no install
Cost	SkyCAD has a free Standard license; Advanced and Pro are subscriptions	KiCad free and open source; EasyEDA free	Free Basic; Standard $2.99 per month or $30 per year

For a course or for learning electronics

The question changes when nobody is going to build a board. A student in a circuits course, a teacher setting up a lab, or someone learning on their own needs a tool that shows what a circuit does and lets them change it and look again. Measured that way, the PCB tools and Tinkercad each have a specific problem, and it is a different problem in each case.

KiCad and EasyEDA put the learning behind the setup. Before a student can watch an RC filter roll off in KiCad, they need to assign a SPICE model to each symbol, set the simulation command, and place probes. For a manufacturer part, they need to find the model file first. That is a reasonable price for an engineer who is going to route the board afterward, and it is a distraction for someone who wants to see the corner frequency move when the capacitor changes. Footprints, layers, and design rules take up most of the interface, and none of them have anything to do with why an op amp saturates. EasyEDA Standard's own FAQ says simulation is not its main target, and the Pro simulator is aimed at checking a design on its way to a board.

Tinkercad stops where the course gets interesting. Tinkercad Circuits is free with an Autodesk account, has a photoreal breadboard view, includes an Arduino simulator with code stepping, and has a classroom mode where a teacher manages a roster. For a first unit on series and parallel resistors, LEDs, and an Arduino sketch, it is a good place to start, and CircuitSim has neither the breadboard view nor the Arduino. Its simulation is transient only, with idealized component models and no custom SPICE models. There is no AC analysis, so no Bode plot or frequency response, and no DC operating point or DC sweep. Once a course reaches a filter, an amplifier, a transistor bias problem, or a diode characteristic, Tinkercad has no analysis that answers the question being asked.

What a SPICE simulator gives a class. CircuitSim runs the analyses a circuits course is built around: DC operating point for bias problems, transient for step response and rectifiers, AC sweep with magnitude and phase for filters and amplifiers, DC sweep with a nested source for transistor curve families, and parameter sweep for the "what happens when R2 changes" questions. Parts such as a TL072 simulate with the manufacturer's model, so the simulated part is the same part that is on the bench. The table panel gives minimum, maximum, and average per trace and exports to CSV or XLSX for a lab report. With a group license, each student gets a private seat behind a link, with no sign-up and no email collected. It also opens Multisim Live files (.ms14, .msjs, .csim, and .zip batches), which matters for departments whose lab manuals were written around that tool before it shuts down on September 15, 2026. CircuitSim for educators covers how a class is set up.

For a circuits course	Tinkercad Circuits	KiCad, EasyEDA	CircuitSim
Breadboard view and Arduino	Yes, both	No	No
AC sweep, Bode plot	No	Yes, after models and a simulation command are set up	Yes, on the free plan
DC operating point and DC sweep	No	Yes, same setup	Operating point on the free plan; DC sweep on Standard
Manufacturer part models	No, idealized parts	Download and attach per part	Named parts carry their models
Student access	Autodesk account; teacher-managed roster	Desktop install (KiCad) or an EasyEDA account per student	Private seat behind a link, no sign-up, no email collected
Opens Multisim Live lab files	No	No	Yes

A practical split for a program: Tinkercad for the breadboard and Arduino unit, CircuitSim from the first filter onward, and KiCad or EasyEDA in the senior design course where a board gets made. We have a longer Tinkercad Circuits alternatives page for the case where a class has outgrown it.

Using a simulator alongside your CAD tool

You will not be in these tools at the same stage of a project, so the practical question is how they hand off. CircuitSim's importer reads Multisim Live files only, and it has no export a PCB tool can open, so a whole design does not move in either direction. Individual parts do.

Simulate first, then draw for manufacture

Settle the circuit in CircuitSim. Use interactive mode to land on values, then confirm with a transient run and an AC sweep. Export the traces to CSV or XLSX if the numbers belong in a design note.
Note the parts and values. Take the values and part numbers from the CircuitSim schematic and redraw it in KiCad or EasyEDA, where you pick footprints.
Bring KiCad symbols back when a part is missing. If you keep a symbol library in KiCad, the custom component studio can import a KiCad symbol and attach a pasted SPICE model to it, so the same part exists in both tools.
Route and order in the PCB tool. Layout, design rule checks, Gerbers, and fabrication ordering all stay there.

For someone working in SkyCAD or another electrical CAD package, the overlap is smaller still. Most of a control panel drawing has nothing to simulate. The analog pieces inside the cabinet do, such as a 4 to 20 mA loop, a sensor conditioning stage, a snubber across a relay coil, or a power supply filter, and those can be worked out in CircuitSim before they become a line on a wiring diagram.

Which tool to open first

If you are a student in a circuits course, an instructor building assignments, or an engineer who wants to know how a stage behaves before drawing it, start in a simulator and move to a drawing tool once the values are settled. For a class, that means Tinkercad for the breadboard and Arduino unit and CircuitSim once the course reaches AC, filters, or amplifiers.

If you already know the circuit works and the job is to get it built, start in KiCad or EasyEDA and use their simulator for the check before layout. If the job is a control cabinet, a machine, or a harness, SkyCAD and its neighbors are the right tools, and you may not need a simulator at all.

Common questions

Can KiCad simulate circuits?

Yes. KiCad includes ngspice inside the schematic editor with operating point, DC transfer, AC sweep, transient, and a custom command mode. Generic parts simulate with ngspice's built-in models. KiCad does not bundle any third-party SPICE model libraries, so a specific manufacturer part needs its model downloaded from the manufacturer and attached to its symbol.

Does EasyEDA have a circuit simulator?

Yes, in both editions, with different engines. EasyEDA Standard's simulation is LTspice-based, and its own FAQ describes it as supporting simple schematics with very few models. EasyEDA Pro added simulation in version 3.2 with a real-time engine called Simulide and ngspice for transient and AC analysis.

Does SkyCAD simulate circuits?

SkyCAD Electrical is electrical schematic software for wiring diagrams, panel layouts, harnesses, and parts lists, aimed at automation and OEM work, and its feature list does not include simulation. Its drawings use control components such as relays, contactors, and terminals rather than SPICE-modeled parts.

Is CircuitSim a PCB design tool?

No. CircuitSim is a browser-based SPICE simulator. It has a schematic editor for describing the circuit, but it has no PCB layout, no Gerber export, and no fabrication ordering, and none of those are in development.

Can I move a design between CircuitSim and KiCad or EasyEDA?

Not as a whole design. CircuitSim's importer reads Multisim Live files only, so a circuit is redrawn in the other tool by hand. The custom component studio can import a KiCad symbol and attach a SPICE model to it, so individual parts can be shared.

Is CircuitSim better than Tinkercad for learning circuits?

For anything past a first unit, yes. Tinkercad Circuits has the breadboard view and the Arduino simulator, which CircuitSim does not, and it is the better choice for that unit. Its simulation is transient only with idealized parts, and it has no AC analysis, DC operating point, or DC sweep. CircuitSim runs all of those with manufacturer part models, on the free plan for AC sweep and operating point, and gives each student a seat with no account.

Should students learn circuits in KiCad or EasyEDA?

Not as the first tool. Both can simulate, but a student has to attach models, write a simulation command, and work around an interface built for footprints and layout before seeing a result. They belong in the course where a board gets designed. For learning how circuits behave, a simulator with parts that already carry their models gets to the result faster.

Why use a standalone simulator when my PCB tool already has one?

Two reasons: the parts library and the edit, run, read loop. A standalone simulator ships with parts that already carry their models, and it is built for changing a value and reading the result many times in a row, with probes, sweeps, and export built in. A bundled simulator covers the check before layout, and works well for that.

CircuitSim is built by Elsewhere Labs, which is Britt and Sam.

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