Thousands have rallied in cities across Australia to “Bust the Budget” but there were large differences in crowd figures given by organisers and police.

They gathered to bust the budget, but it seems the only thing that’s broken is their basic arithmetic.

Huge discrepancies have emerged between figures provided by the Bust The Budget March organisers and authorities, with Sydney members of the anti-budget cohort initially claiming between 30,000 and 50,000 people attended.

“(They) filled two blocks of Market St across all lanes,” organiser Jane Salmon said in a statement on Sunday, before later updating the her estimate to “closer to 15,000 than 50,000.”

Sydney police told AAP about 6,000 people turned out.

Melbourne organisers say police estimated a crowd of 25,000, but when contacted for comment police said they didn’t provide figures for protests.

It was the same for Adelaide, with Bust The Budget claiming 4000 had gathered and police refusing to say how many they believed attended.

In Brisbane, however, police said about 1000 people marched, which accords with the group’s claims of 800 protesters.

No one was arrested in any of the cities, Queensland, NSW, Victorian and SA police told AAP.

About 300 people rallied in Perth, with moderate to heavy rain falling across the city.

Across the country the Bust The Budget marches drew an eclectic mix of religious, trade union, student and political groups.

Several of the government’s budget measures, including the $7 GP visit co-payment, changes to jobless benefits, a higher pension age and deregulation of university fees have been criticised as unfair by the budget busters.

Greens leader Christine Milne told Sydney reporters the protest was borne out of frustration with planned federal cuts to health and welfare spending.

“(Tony Abbott) is making life a misery for people who are unemployed and searching for work,” she said.

“You need to join with us in busting the budget.

“Tony Abbott is a crash or crash through prime minister. We have to make sure that in response to this budget we make sure he crashes.”

Unions NSW secretary Mark Lennon said there hadn’t been such continuous outrage against a budget in 30 years.

“People are going to come here to Town Hall and make it very loud and clear what they think about what happened on May 13,” he said, urging incoming senators to vote the budget down.

Many of those who marched in Adelaide were at their first political rally, SA Unions state secretary Joe Szakacs told AAP after the demonstration in the city’s centre.

They felt “it’s time to fight back,” he added.

“We had a very broad cross section of the community.”

“Pensioners, young people, students, working people, people with disabilities, families … because we know that this budget attacks everybody and no-one is safe.

“Collectively now, those people are standing up.”