How do you calculate centile lines for baby weight?

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I can’t find my red book and baby has only been weighed twice ! Once at birth and once at 1 year !

At birth (38 W exactly) she was 7lb 8
Now at 1 year and 4 days she is 25lb 5oz

How can I work out her centile I tried to look online but couldn’t find a calculator

Tia

I have an app on my phone called Growth

https://www.rcpch.ac.uk/sites/default/files/Girls0-44yearsgrowthhchart.pdf