A new interactive map that allows women and girls to report incidences of harassment is being rolled out across Sydney today.

Key points: Plan International's head of advocacy says 90 per cent of girls in Sydney feel unsafe

Plan International's head of advocacy says 90 per cent of girls in Sydney feel unsafe A survey commissioned by the organisation revealed women were having bad experiences in busy places

A survey commissioned by the organisation revealed women were having bad experiences in busy places Sydney high schooler Lauren Lancaster says she is not suprised by the survey results

The "Free to Be" map is aimed at 15 to 25-year-olds and allows them to drop a "good" pin on locations in the city where they feel safe and a "bad" pin on spots where they feel uncomfortable or unsafe.

The tool is the initiative of the NGO Plan International Australia, which commissioned a survey of more than 400 young women ahead of the launch.

"We've found 90 per cent of girls in Sydney are feeling unsafe being in their city at night," said Plan's head of advocacy, Hayley Cull.

"That's an extraordinary statistic."

Hayley Cull says 90 per cent of girls in Sydney are "feeling unsafe at night". ( ABC News: Barbara Miller )

The numbers do not surprise 16-year-old Sydney high school student Lauren Lancaster, one of a dozen or so ambassadors for the Free to Be map.

Ms Lancaster said she first experienced street harassment at the age of 11 or 12, when a group of men in a car verbally abused her and her friends.

"That really stuck with me," she said.

"I'd never really experienced anything like it and it really confused me as to why they would be allowed to do that, or they felt that they could do that."

Lauren Lancaster says she is often confronted by harassment in crowded places. ( ABC News: Barbara Miller )

These days the teenager said she was often confronted by harassment, including cat-calling and men whispering in her ear on public transport.

"It's repeated, it's small things that build up into having a much bigger effect on us as young girls," she said.

The interactive map allows participants to anonymously provide details of incidents of harassment.

"At the moment there's no mechanism for reporting any kind of harassment that doesn't seem like the most severe, most extreme sort of that," said Ms Cull.

"That's what's making it invisible."

Melbourne trial delivered 'surprising results'

The map is also being launched today in New Delhi, Kampala, Lima, and Madrid. A pilot project that ran in Melbourne two years ago resulted in more than 1,300 pins being dropped.

The director of the XYX Lab at Monash University and lead researcher on the project, Dr Nicole Kalms, said it delivered surprising results.

"What we would normally think of as unsafe spaces, such as dark laneways or being out on a Saturday night, were really not the kinds of experiences that women and girls wanted to share," she said.

"What we discovered was that women and girls were having bad experiences in really busy places — so places like public transport, or retail districts … they were really experiencing a lot of sexual harassment and sexual assault."

How safe do young women feel in Sydney? A survey conducted by Plan International found: 90 per cent said they sometimes or always felt unsafe in the city at night

90 per cent said they sometimes or always felt unsafe in the city at night 92 per cent felt uncomfortable taking public transport alone at night

92 per cent felt uncomfortable taking public transport alone at night Half (49 per cent) had experienced street harassment

Half (49 per cent) had experienced street harassment Two-thirds (66 per cent) agreed street harassment was commonly experienced by young women in Sydney A total of 452 women aged 18-25 were interviewed in Sydney in early April, 2018.

Dr Kalms said she expected the results of the Sydney map study would vary from the Melbourne study, due to the differences in each city's geographical layout.

"One of the main things that's different in Sydney is that it's not just a central city. It's a whole, four or five decentralised cities," she said.

As a result of the Melbourne study, Plan International Australia is now working with Metro trains to try and make trains safer for young women.

The organisation is also talking to the police and local councils about its results.

The findings of the six-week Sydney survey will also be shared with local authorities and businesses in an attempt to encourage them to make modifications to spaces deemed unsafe.

Kripa Krithivasan says the fear of being harassed affects the way she dresses and acts. ( ABC News: Barbara Miller )

21-year-old Sydney student Kripa Krithivasan said the threat of street harassment "affects the way I act, it affects the way I dress, it affects how I plan my day or plan my night".

"I feel like I need to take a jacket with me everywhere I go so I can zip it up if I'm in an alleyway," she said.

"I can't really wear short skirts with heels because you know that really puts focus on areas that I don't want to enhance."

Ms Krithivasan said she hoped the Free to Be project would lead to change.

"We need to make the city safer, not the girls in the city stronger against this," she said. "Because we're already strong".