The present invention relates to a variable flow valve, in particular for filling with a foaming fluid. Preferably, but not exclusively, the valve of the invention can be used in net weight filling machines.In particular, the invention relates to a filling valve (1) for filling machines comprising a hollow body (2) which encloses a cavity (4) in which a filling fluid is introduced and which opens at its bottom into a dispensing opening (5), a shutter (3) being axially sliding in the cavity (4), wherein the shutter (3) comprises a tip (6), adapted to shut the dispensing opening (5), a stem (7) and an adjusting member (16) for adjusting the flow rate of the filling fluid, characterized in that the adjusting member (16) comprises a toroidal body (17) arranged coaxially with respect to the stem (7) and floating with respect thereto.