Bode Plot Generator

Bode Plot Generator is a free online calculator that computes frequency-response plots from polynomial transfer functions entered by the user. It accepts numerator and denominator coefficients, generates magnitude and phase Bode plots on a logarithmic frequency axis, and displays characteristics such as gain margin, phase margin, gain and phase crossover frequencies, DC gain, poles, and zeros. Users can export the computed plots as CSV or SVG files, and preset transfer functions are provided for common filters and controllers. The tool runs entirely in the browser and does not require an account.

The website provides preset transfer functions for common filters and controllers, including first-order low-pass, first-order high-pass, band-pass, integrator, second-order resonant, lead compensator, PID controller, and unity-feedback loop. Users can select these presets to quickly analyze standard system configurations.

The interface allows users to enter coefficients using commas or spaces in descending power order, including zero placeholders like '1, 0, 4' for s² + 4. Users can specify a minimum and maximum frequency, choose the frequency unit as rad/s or Hz, and generate plots with a single click.

The magnitude curve is calculated as 20·log₁₀|H(jω)|, while the phase curve is the angle of H(jω) unwrapped continuously to follow accumulated phase lag past −180° instead of seeing it jump. This continuous unwrapping helps engineers see the full phase behavior.

Gain margin is read at the phase crossover frequency where the phase reaches −180°, showing the distance from the magnitude curve up to 0 dB. Phase margin is read at the gain crossover frequency where the magnitude crosses 0 dB, showing the distance from the phase curve up to −180°.

The tool is designed for engineers working with linear time-invariant (LTI) systems, control systems, filter design, and stability analysis. It is particularly useful for those who need to visualize how close the loop gain is to 0 dB when the phase reaches −180° to decide if a feedback system will ring, oscillate, or settle cleanly.

Some reviewers on Reddit mention that the tool is essential for control systems, filter design, and stability analysis. Users appreciate the step-by-step analysis features, zeros/poles identification, and interactive dual-subplot graphs.

The website states that the tool runs entirely in your browser and does not require an account. It is completely free to use with no hidden costs or subscription fees mentioned.

The tool supports multiple languages including English, Deutsch, Español, Français, Bahasa Indonesia, Italiano, 日本語, 한국어, Português, Русский, and Türkçe. Users can switch between these languages directly on the interface.

The tool allows users to inspect a sample point at a plot using keyboard focus with Left/Right or Home/End keys. This feature helps users navigate the graph without a mouse.

The tool provides a built-in Python compiler for step-by-step analysis, allowing users to run code directly within the interface for deeper exploration of their transfer functions.

The tool was last updated in 2026 and is currently in version 2.0. It has been reviewed on Trustburn with a rating of 3.8 out of 5 from 5 reviews.

The official website of Bode Plot Generator is bodeplotgenerator.com.