Spending on new health and education projects is more than twice as much as forecast by the NSW budget just three years ago.

The amount of new infrastructure spending announced in NSW state budgets has grown each year since 2015 with broken records for investment announced annually.

The gap in 2018-19 between what was forecast to be spent on new projects in 2015 and what is in the budget this year is $6.74 billion.

Delivering the 2018-19 budget, NSW Treasurer Dominic Perrottet said he was "building on last year’s unprecedented commitments with new record investments in schools, hospitals and transport links".

The biggest shifts in spending, from what was predicted in 2015, have been in health and education as well as a saving of more than $1 billion for electricity infrastructure.