Engineering Plots — Bode, Nyquist & root locus plotter
Engineering Plots is a free online tool for drawing the three classic plots used to analyse and design control systems, straight from a transfer function H(s) = N(s) / D(s). Enter the numerator and denominator as coefficients or as typed polynomials and the plots are generated instantly in your browser — no installation, no account, and no cost.
The tools
Bode plot
Magnitude (in decibels) and phase (in degrees) versus frequency on a logarithmic axis, with gain and phase margins and crossover frequencies marked automatically.
Nyquist plot
The full Nyquist diagram of H(jω) in the complex plane, including the −1 critical point, the direction of travel, and the closing arcs at infinity for systems with poles on the imaginary axis.
Root locus
The closed-loop pole branches as a gain K varies, drawn with asymptotes, breakaway and break-in points, and imaginary-axis crossings, plus the gain K and damping ratio at any point on a branch.
Learn the theory
Short, plain-English guides explain how to read a Bode plot, what gain and phase margin mean, the Nyquist stability criterion, and the rules for sketching a root locus.
Free, private, and instant
Every calculation runs in your browser, so the transfer functions you enter never leave your device. There is nothing to install and no sign-up required.