Microcap 12 Review

Microcap 12 Logo

Microcap 12 is a formerly commercial circuit simulator that has been made freeware, it was developed by Spectrum Software since 1982 with the final release coming in 2020, while there will no longer be any updates Microcap 12 is fully functional and mature software.


Microcap 12 Interface
Default Interface

Microcap has a lot of functionality so as might be expected the interface is a tad cluttered, however compared with some other professional circuit simulation software it really isn’t too bad, the manual, user guide and reference manual provides plenty of help.

There is a great deal of customization options available including interface layout, keyboard shortcuts, colours and fonts which makes it very versatile.

Part Selection

The included parts library is very extensive containing over 45,000 parts, including useful macro models, while it may be a bit lacking in terms of the most modern parts, there is still enough for essentially every need, in addition in can import standard SPICE models and subcircuits.


A wide variety of simulations are available, from the standard DC, AC and transient to harmonic / intermodulation distortion, stability and optimization, for a free simulator this is by far the best I’ve seen, a number of interactive options are included as well such as sliders and animated parts which makes it very good for educational usage.

There is an extensive amount of graphing options including formulae, annotation, FFT, monte carlo and more making it a very powerful tool.

Multicap 12 Analysis


Microcap 12 is currently the best value circuit simulator that can be had, it even beats a number of commercial products in terms of functionality and component library, what I find more surprising is that Spectrum Software have decided to make this freely available rather than simply vanish like so many companies do these days.

You can get Microcap 12 for free from the Spectrum Software website.

3 thoughts on “Microcap 12 Review”

  1. they all seem to be all singing all dancing but none give a real reading
    if i put 1 f.e.t 2 resister 1 constant voltage i get nearly the correct answerer from d or s
    if i make up a circuit with more than 3 f.e.t the output can be 100%
    wrong im betting its because models are perfect and in reality we know that
    any 2 fet,s from the same batch will have a marked difference in gain so where does that leave
    us or am i missing something very important i suspect i am let me know please

    1. You are correct there is a lot of variation with FETs that is not modeled in circuit simulators, the solution to this is parameter stepping, most simulators support this and allows you to step any device parameter such as the threshold voltage so you can see the impact on your simulation, in microcap this is found in the stepping dialog (F11), other SPICE based simulators usually have a .STEP command to do this.
      There is an example of stepping in the microcap samples under ‘Voltage Controlled Oscillators\VCO2.cir’.

  2. It’s really nice of them to give this software. That said I would be extremely mad if I had paid for it. I made the mistake of trying the software for a margin analysis job I have and I am presently trying to probe a current for a capacitor, it’s taking several minutes to probe anything. Their software is probably fine for short simulations or simple idealistic models, but I don’t think it’s suitable for serious analysis work, for that I would recommend buying PSpice. It’s gonna take 10 times as long to process my results as it would with LtSpice or Pspice. And this is for a simple model that runs in about 5 minutes, I’m glad it’s not a complex model that takes say 16hrs. I was hoping the spreadsheet would help, but the spreadsheets only give you the last value, so for example =PD(R1) gives you the power dissipated by R1 at the very end of the simulation, ok so maybe AVG(PD(R1)) will get the average power for the entire simulation, no dice, just like MAX(ABS(V(R1))) just gives you the last voltage measured across R1, not the maximum over the whole simulation, so everything has to be probed by hand. Smoke might be nice for this if it would work with subcircuits, but the reality is that for many applications using ideal transformers, capacitors, inductors simply does not provide adequate accuracy Alright, back to probing, looks like I’ll be doing this all day and into the night.

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