Nuclear equation of state describes how energy and pressure in nuclear matter vary with changes in densities of neutrons and protons. When nuclear matter gets compressed in energetic nuclear collisions, the pressure building up pushes nuclear matter to the side, giving rise to collective motion that correlates nucleons outgoing to the detectors. Systematic studies of these correlations allow to arrive at constraints on the pressure in nuclear matter as a function of density. In neutron stars, the pressure of compressed nuclear matter opposes gravity, preventing collapse of the stars into black holes. The nuclear matter equation of state determines the size and maximum mass of a star, among other star features. Gravitational waves from a merger of neutron stars test characteristics of the stars dependent on the equation of state and allow to place constraints on that equation as well. Findings from the laboratory and gravitational wave measurements will be compared.