The nation's top cultural institutions are weighing up how many staff to let go as they grapple with budget cuts.

The Turnbull government announced a three per cent efficiency dividend in its mid-year budget update last December, totalling $36.8 million.

The Museum of Australian Democracy, which sits inside Old Parliament House, will have fewer exhibitions and will run them longer as a result, its director told a senate hearing in Canberra on Tuesday.

Daryl Karp also predicts the museum will do one less significant event each year.

Funding in 2015/16 is approximately the same as when the museum was set up in 2007/8, she said.

"We've cut fat, we've cut muscle, we are now looking at what do we stop doing."

The National Gallery of Australia is in line to lose $4 million over the next three-and-a-half years.

Gerard Vaughan says they plan on maintaining their blockbusters, but will probably have to lose more than 10 staff.

The National Library will suffer a $6 million funding decrease, with an expected eight to 10 positions to go.

"First of all we will seek to work with natural attrition," director-general Anne-Marie Schwirtlich said.

National Portrait Gallery director Angus Trumble said it will have to cut "pretty much everything", including a chunk of advertising.

"Regrettably there will be an impact on our staff," he said, expecting three positions out of about 50 will go.

But he doubted closing on Monday - an idea previously raised - would make an appreciable savings difference.

Michael Loebenstein, National Film and Sound Archive CEO, said staffing losses will be unavoidable, but it is not looking to close any of its sites.

Communications Minister Mitch Fifield said he was staying in close contact with the agencies.