The magneto-optical technique was used to study the edge barrier for flux entry in type I superconducting strips (In, Pb). The width of the flux-free zones appearing at the sample edges, due to the barrier, was measured at different applied fields and temperatures. Standard I–V measurements allowed us to study the critical current originated by the edge barrier in these pinning-free samples and its dependence on different parameters like magnetic field, temperature and sample's size. Our results confirm the geometrical origin of this edge barrier and show its dependence on different relevant variables.