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# Reduce PDF Size
There are multiple ways to reduce the size of a given PDF file. The easiest
one is to remove content (e.g. images) or pages.
## Removing duplication
Some PDF documents contain the same object multiple times. For example, if an
image appears three times in a PDF it could be embedded three times. Or it can
be embedded once and referenced twice.
This can be done by reading and writing the file:
```python
from PyPDF2 import PdfReader, PdfWriter
reader = PdfReader("big-old-file.pdf")
writer = PdfWriter()
for page in reader.pages:
writer.add_page(page)
writer.add_metadata(reader.metadata)
with open("smaller-new-file.pdf", "wb") as fp:
writer.write(fp)
```
It depends on the PDF how well this works, but we have seen an 86% file
reduction (from 5.7 MB to 0.8 MB) within a real PDF.
## Remove images
```python
from PyPDF2 import PdfReader, PdfWriter
reader = PdfReader("example.pdf")
writer = PdfWriter()
for page in reader.pages:
writer.add_page(page)
writer.remove_images()
with open("out.pdf", "wb") as f:
writer.write(f)
```
## Lossless Compression
PyPDF2 supports the FlateDecode filter which uses the zlib/deflate compression
method. It is a lossless compression, meaning the resulting PDF looks exactly
the same.
Deflate compression can be applied to a page via [`page.compress_content_streams`](https://pypdf2.readthedocs.io/en/latest/modules/PageObject.html#PyPDF2._page.PageObject.compress_content_streams):
```python
from PyPDF2 import PdfReader, PdfWriter
reader = PdfReader("example.pdf")
writer = PdfWriter()
for page in reader.pages:
page.compress_content_streams() # This is CPU intensive!
writer.add_page(page)
with open("out.pdf", "wb") as f:
writer.write(f)
```
Using this method, we have seen a reduction by 70% (from 11.8 MB to 3.5 MB)
with a real PDF.
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