A new seat will be created in Melbourne's rapidly growing western suburbs as part of an overhaul of Victoria's electoral boundaries.

On Thursday morning the electoral commission will release maps of proposed boundaries of the state's 88 lower house seats.

Peter Walsh. Credit:Eddie Jim

Electoral boundaries are redrawn sporadically to ensure that all seats have roughly the same population and to tackle population growth and decline.

Nearly 40 per cent of electorates are too big or too small - seats must each have 41,473 voters, or be within 10 per cent of that figure.