  We show that decaying turbulent non-helical magnetic fields satisfy a
self-similarity relation according to which the relevant scales increase as
time passes (inverse cascade or inverse transfer). We compute analytically
quantities which have previously been determined by numerical calculations, for
example the average energy and the integral scale which are proportional to 1/t
and the square root of t,respectively, where t is the time. We also briefly
discuss self-similarity for the helical case.
