Magnetic helicity is a general measure of the twist and mutual linking of magnetic field lines that has recently received wide attention from different areas of Astrophysics. We propose an International Team formed by experts in magnetic helicity studies from different disciplines, such as stellar dynamos, solar corona and coronal mass ejections, magnetic turbulence and reconnection, both in theoretical models as well as in numerical simulations and solar observations. The main objective of the International Team is to bring helicity estimation methods that were developed in different fields under the same theoretical framework, so that they can be meaningfully compared with each other, and quantitatively benchmarked. In particular, we will consider helicity computations based on spectral methods applied to periodic domains (as used in free decaying turbulence and solar wind studies) and non-periodical domains (more typical of low-corona solar applications), and compare them with the finite-volume and flux-injection methods typically used in magneto-hydrodynamical simulations as well as in solar observations. Novel methods applying helicity estimations to individual field lines and their application to volume-filling fields will be also included. The comparison between different methods will be performed using numerical simulations as controlled test-cases to provide quantitative benchmarking and clear indications of the methods’ limitations and assumptions. Their application to observed solar data, on the other hand, will allow to confront such methods with the additional complexity of real observations.