Dimensional analysis is a powerful method to analyse complex physical phenomena, including those for which we cannot pose, much less solve governing equations. Its use in science and engineering is ubiquitous and has been central to the work of greats such as Lord Rayleigh, Bohr and Einstein. It offers a method for reducing complex physical problems to their simplest forms and provides a powerful tool for checking whether or not equations are dimensionally consistent and suggests plausible equations when we know which quantities are involved. Every scientist and engineer should have this tool at their command, and this book provides an accessible, modern, self-contained and systematic overview. It outlines the principles of similitude and presents the tools of dimensional analysis for both scientists and engineers and how it can be applied practically to aid not only a greater understanding of theoretical concepts but in designing experiments and analysing experimental data. With examples relevant to a wide range of students and not limited to the physical and engineering sciences, but encompasses the biological and life sciences. The technique has, for example, been used to estimate the running speed of a hungry Tyrannosaurus rex, a comparison of the flights of mosquitos and jet airliners, and the energy released by an atomic weapon. Key Features Draws on and presents examples across the physical, chemical and life sciences, as well as engineering applications Emphasises the technique as a tool and empowers readers to apply the method in developing their own experiments and theoretical understanding Includes methods, history and applications An engaging, accessible, self-contained and systematic resource.