Almost half of girls aged 11-16 years old regularly use apps or filters to make themselves look better, according to a new survey.
The report by Girlguiding found 45% of that age group are often using the software to change their appearance.
Alice, age 15, said: "The 'perfect' images girls are encountering in their daily lives is having a devastating impact on girls' self-esteem and confidence, which not only negatively impacts their wellbeing but adds to pressures they already face in their lives".
However, the results also found that 69% used apps or filters on their phone because it's fun and creative.
The survey also asked about advertising online, with 43% of girls saying they had seen adverts online that made them feel pressured to look different.
Meanwhile, 64% of those asked thought that diet products and weight loss clubs shouldn't be advertised to children under the age of 18.
"Our new research highlights the concerning amount of pressure faced by girls and young women on a daily basis," said Girlguiding Chief Executive, Angela Salt.
"It is imperative we continue to support their wellbeing and help build resilience and confidence."