Introduction

What is Symbulator

Symbulator is an app that solves linear electric circuits symbolically and numerically, on any device with a browser. It takes numerical and symbolic values, and returns numerical and symbolic results. The odd-sounding name is a portmanteau of "symbolic simulator". Symbulator is widely regarded as the best portable symbolic simulator of linear electric circuits.

What analyses can it do?

Symbulator can solve circuits using four types of analysis: direct current (DC), alternating current (AC), transient time-domain (TR), and complex frequency-domain (FD). It analyses numerical and, more importantly, symbolic linear circuits, returning the voltages in all nodes and the currents, voltage drops and power in all elements. It also finds the passive, Thévenin / Norton and two-port equivalent of a circuit, and draws time domain and Bode plots.

What elements does it accept?

Symbulator accepts elements such as resistors, inductors, mutual inductance, capacitors, independent and dependent current and voltage sources, ideal operational amplifiers, ideal transformers and six types of two-ports.

Where does it run?

Symbulator 9, released in 2026, is a port of the classic code to Python, powered by the SymPy computer algebra library. It runs anywhere Python runs: your mobile phone, tablet, laptop, a Jupyter notebook, or a browser on any computer. Version 9 solves circuits faster than versions 7 and 8.

Why use Symbulator?

Symbulator is extremely useful on the circuit theory problems engineering students face in Circuits I and II. It lets the student focus on understanding circuit analysis rather than on the mathematics of solving it.

Strengths

• A fantastic tool to solve circuits composed of ideal, linear elements.
• Shines in solving circuits with symbolic values, and symbolic results.
• Offers the absolute simplest way to define dependent sources.
• Includes ideal transformers and six different two-ports.

Limitations

• Does not simulate non-linear elements, such as diodes and transistors.
• Will not answer under-defined problems that rely on applying formulas selectively rather than solving a circuit completely.
• Is not a replacement for your brain or an excuse to not study. You must understand circuit theory to use it.

Symbulator is free!

Symbulator has always been free of charge, and always will be. (You are welcome!) Since 2026, Symbulator is also open source under the MIT licence. You are free to use it, change it and port it to other platforms; all the licence asks is that the copyright notice and the attribution to the original author travel with it.

Get Symbulator

You can use Symbulator 9 in two ways:

• as an online app running on a remote server, or
• as an offline app running locally on your device.

The easiest way to start is the online app.

To run it offline on your own device, follow the instructions at the bottom of the online app, under Run Symbulator 9 locally.

Please report any problems to help [at] symbulator [dot] com

Built-in examples

You do not have to type the tutorial's circuits. The Built-in examples list at the top of the app holds an entry for every simulation in every lesson; click a title to load one and solve it as if you had typed it yourself.

Working with input files explains how to load them, save your own work, and download it to your device. It is a technical note, in the section of that name at the end of this tutorial: optional reading, there when you want it. Nothing in the lessons depends on it — you can follow every one of them without saving a file.

Reading and running side by side

This tutorial has you moving between the page you are reading and the app you are running. Two windows work. There is a tidier way.

The split view puts both in one window: the documentation on the left, the live app on the right. Drag the divider to resize them; on a phone or a narrow window they become two tabs. Both halves are the real thing, simply shown together.

The two halves are connected. On the website, every worked problem carries two links under its title:

• Open in app ↗ loads that circuit, with its analysis and settings, ready to run.

• Open in split view does the same, but in the split view, on the problem you were reading.

Inside the split view, Open in app ↗ loads the circuit into the right-hand pane instead of a new tab, and the second link is not shown.

A problem with more than one simulation carries a link for each, marked DC or TR. A few problems have no link, because they are worked by hand.

The split view keeps its address current as you move, so it can be shared where you are. Send someone:

learn.symbulator.com/split/?lesson=6a&entry=3

and they open on the same problem, with the same circuit loaded.