Hydrodynamics is an important tool for predicting large-scale behaviour of many-body systems. Due to its universality, one expects that specific microscopic implementation should not matter. In this work, we show that classical deterministic circuits provide a minimal, exact, and efficient platform to study non-trivial hydrodynamic behaviour for deterministic but chaotic systems. By developing new techniques and focusing on 1D circuits as a proof of concept, we obtain the characteristic dynamics, including relaxation to Gibbs states, exact Euler equations, shocks, diffusion, and exact KPZ super-diffusion. Our methods can be easily generalised to higher dimensions or quantum circuits.