Twice as many Australians would get faster fibre-to-the-home internet connections under a future Shorten government, but the rollout of the NBN would cost taxpayers at most only $1 billion more and would be completed in the same time, Labor says.

In a pitch to younger voters, universities and businesses that rely on fast internet speeds for e-commerce, Labor will on Monday promise a move away from Prime Minister Malcolm Turnbull's cut-price part-copper national broadband network and to connect an extra 2 million homes and businesses by June 2022.

This is the same time frame promised by the Coalition government, but under Labor 39 per cent of homes and businesses would get fibre to the premises – up from 20 per cent under the current plan.

Crucially, Labor will also promise to cap the cost of the NBN at $57 billion – $1 billion more than the Coalition's NBN, which has itself blown out in cost from an original estimate of $29.5 billion.