A Fairfax Media analysis of HSC results reveals the continuing impact of postcodes on academic success, despite record levels of funding aimed at stemming chronic educational inequality.

The new data shows how school performance is cleaved along the so-called "latte line" that also divides the city along socio-economic lines.

"If you are north of that line you are largely a 'have'," Geoff Roberts, the economic commissioner of the Greater Sydney Commission said last week, referring to the socio-economic status of Sydneysiders.

"If you are south of that line, you are largely a 'have-not."

Fairfax Media mapped nearly 330 metropolitan schools according to the share of exam results that scored 90 or above in this year's HSC. Schools in blue performed in the top half of the list; schools in red performed in the bottom half.

Nearly 90 per cent of Sydney's 55 highest-performing schools (shown in dark blue) are located either on or above the line, which stretches diagonally from Rouse Hill in the north-west to Tempe in the south-east.

Less than 25 per cent of the schools below the line performed in the top half of the honour roll, according to the analysis. Above the line, nearly 85 per cent of schools were ranked in the top half.

The rift becomes even more stark when selective schools are excluded. In that case, none of the top-performing schools, in dark blue, are below the line.

But the reality could be worse. The map excludes dozens of schools that failed to achieved one Band 6 score of 90 or above. Many of these would be located below the line.

"This clearly shows there is a direct correlation between results and postcodes and is the very reason needs-based funding is so important," said NSW Labor education spokesman Jihad Dib.

Government schools struggled hardest to buck the trend, with only six of those below the line finishing in the top half of honour roll schools.

A separate Fairfax Media analysis of public schools by their local government area prior to amalgamation, shows educational disadvantage is being cemented in some of the areas tipped to have the state's largest population booms.

In Camden, for example, which will see the biggest growth in school-aged population of any Sydney local government area over the next decade, students achieved Band 6 scores in only 3 per cent of exams.

In this area, student numbers are set to surge by up to 55 per cent by 2026, according to NSW Department of Planning projections.

The percentage of Band 6 scores was just as low among students in Blacktown and Liverpool, where the school population is projected to boom by roughly 25 per cent over the next decade.

All three local government areas are below the line.

It's a far cry from the results of students north of the line in the City of Sydney, The Hills Shire and Hornsby LGA. Here, students achieved Band 6 scores in up to 28 per cent of exams, according to Fairfax Media's analysis, which does not include results from students who sat the International Baccalaureate.

The data also reveals some of the state's hottest properties are found in neighbourhoods straddling the line, suggesting parents hoping to give their children the best shot at HSC success are driving up house prices in Strathfield, Ryde, Cherrybrook and Castle Hill.

Eight out of the 10 public school catchment areas with the highest growth are along the border, according to 2015 figures from the Fairfax Media-owned Domain Group. The median house price in neighbourhoods surrounding Strathfield Girls, for example, one of the highest-performing public schools, surged to $1.7 million last year.

Pete Goss, the school education program director at the Grattan Institute, said a range of different ways of looking at education outcomes confirmed student background made a difference.

"We have known about this for a long time but we are not finding any ways of making it go away," he said.

NSW Education Minister Adrian Piccoli said the government's new resource allocation model "addresses exactly this issue".

"Student results should not be determined based on where a student lives or the school they go to," he said.

"Hundreds of millions of dollars in additional needs-based funding have gone to schools in south-western and western Sydney, targeted to the students who need the most support."

But state budget figures show that despite record total levels of school funding, the share directed to education has shrunk over the past decade. Education now makes up 21 per cent of total spending compared with 26 per cent in 2003.

The Fairfax Media analysis comes after the latest PISA results, which tested thousands of teenagers around the world and highlighted widening educational disparity between Australian students.

Australia's PISA results found 15-year-olds in the most socio-economically disadvantaged 25 per cent were a full three years' schooling behind the top 25 per cent.

However, the map also reveals dozens of schools in lower socio-economic areas - including Canley Vale High, Bonnyrigg, Fairvale, St Johns Park, Birrong Girls and Liverpool Girls - that achieved remarkable HSC outcomes despite an increasingly unequal playing field.

"Our school does have really high expectations of our kids," Fairvale principal Kathleen Seto told Fairfax Media last week.

"Our community is very multicultural and very poor but very aspirational."

Greenacre's Malek Fahd Islamic school is another institution that defied its postcode and the socio-economic status of its many migrant families.

Earlier this year, the 2100-student school was also threatened with having its funding taken away from it by the federal government after an investigation found the private school was operating for profit following allegations of six-figure loans to some board members.

Teachers, desperate to reassure students they would get through their HSC, started planning to set up classrooms in their living rooms and garages.

"I think the future of the school, and whether there was going to be a school to actually sit the exam in was definitely a difficult thing to handle, but it actually turned out for the best in the end," said student Majed Kheir.

This year's students achieved scores of 90 or above in 18 per cent of their exams.

The school's future remains in the balance pending an appeal that will decide whether the school continues to receive funding it next year.

In April, the school was granted a last-minute stay by the Administrative Appeals Tribunal as the federal government moved to withdraw $19 million in funding.

For now, teachers aren't taking the results for granted.

"It just shows how resilient the kids can be. We gave them extra hours, extra tuition time, Saturday classes," said Tulin Bragg the school's curriculum co-ordinator.

"It gave them comfort that the doors were always going to be open for them, whether it's our school doors or garage doors or our house doors. It brought out the best in us."