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.
Step/impulse response
The time-domain step and impulse response, showing overshoot, settling time, rise time, and the steady-state value.
Open the step/impulse response tool
More control & signals tools
Engineering Plots has grown into a full suite of free control-systems and signal-processing calculators, all running client-side in the browser:
- Pole-zero map — plot the poles and zeros of a transfer function in the s-plane and read off stability.
- Second-order explorer — set the damping ratio ζ and natural frequency ωₙ and watch overshoot, peak time, and settling time change.
- Routh-Hurwitz calculator — test the stability of a characteristic polynomial from its Routh array, with no root-finding.
- PID simulator — tune Kp, Ki, and Kd on any plant and see the closed-loop step response update live.
- State-space converter — turn a transfer function into its A, B, C, D matrices in controllable canonical form.
- Convolution visualizer — flip, slide, multiply, and integrate two signals to build up y(t) = f ∗ g.
- Fourier transform tool — take the Fourier or inverse Fourier transform of a signal, with time and frequency graphs in Hz or rad/s.
- RC / RLC filter calculator — compute cutoff and resonant frequency, time constant, Q, and damping, with a live magnitude and phase response.
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.