Compress PDF
Rasterize and recompress PDF pages with adjustable image quality and resolution
Compress PDF — what it does
Shrink a PDF by rendering its pages as images and re-encoding them at a JPEG quality and resolution you control. It is the blunt but effective route: a scan-heavy or image-heavy PDF that resists every other method usually collapses in size once its pages are re-rendered.
When this tool helps
- Getting a scanned document under an email or upload size limit.
- Reducing an image-heavy presentation exported as PDF before sharing it.
- Making a large document set practical to store or send in bulk.
How to use it
- Choose the PDF file.
- Set the JPEG quality.
- Set the render resolution.
- Compress and compare the original and new sizes.
Accuracy, limits, and good practice
- Rasterising destroys selectable text — the output is pictures of pages, so search, copy and screen readers all stop working.
- Resolution matters more than quality for legibility: 150 DPI stays readable on screen and in print, while 72 DPI is screen-only.
- For a text-based PDF that is merely large, try removing annotations or embedded attachments before resorting to rasterisation.
Frequently asked questions
Why did my text-based PDF get bigger?
Because text compresses far better than images of text. Rasterising a text document is usually the wrong tool for it.
Can I still search the compressed file?
No. Text becomes part of the page image, so searching and copying are lost unless you run OCR afterwards elsewhere.
What quality setting should I use?
Around 0.7 with 150 DPI is a good starting point for scanned documents that need to stay readable.
Related tools on this site
- PDF Bates Numbering — Add sequential document-control numbers with a custom prefix and position
- PDF N-up Layout — Place 2 or 4 PDF pages on each output sheet
- PDF to Images — Render PDF pages as JPG or PNG files
Everything above runs inside this page. Compress PDF needs no account, no upload, and no server round trip — close the tab and nothing is left behind.
PDF 壓縮能做什麼
把 PDF 頁面算繪成影像，再以你控制的 JPEG 品質與解析度重新編碼，藉此縮小檔案。這是粗暴但有效的路線：掃描或圖片為主、其他方法都壓不動的 PDF，重新算繪後通常會大幅變小。
什麼時候用得上
- 讓掃描文件符合郵件或上傳的容量限制。
- 分享前縮小以 PDF 匯出的圖片密集簡報。
- 讓大批文件在儲存或寄送上變得可行。
使用步驟
- 選擇 PDF 檔案。
- 設定 JPEG 品質。
- 設定算繪解析度。
- 執行壓縮並比較原始與新的大小。
精確度、限制與實務建議
- 點陣化會摧毀可選取文字——輸出是頁面的圖片，搜尋、複製與螢幕閱讀器都會失效。
- 就可讀性而言解析度比品質更關鍵：150 DPI 螢幕與列印都清楚，72 DPI 只適合螢幕。
- 若是純文字但檔案偏大的 PDF，先試著移除註解或內嵌附件，再考慮點陣化。
常見問題
為什麼我的文字型 PDF 反而變大了？
因為文字的壓縮效率遠高於「文字的圖片」。對文字文件點陣化，通常是選錯了工具。
壓縮後還能搜尋嗎？
不能。文字已成為頁面影像的一部分，除非之後另外做 OCR，否則搜尋與複製都會失效。
品質該設多少？
掃描文件若要維持可讀，約 0.7 品質搭配 150 DPI 是不錯的起點。
本站相關工具
- PDF Bates 編號 — 加入連續的文件管理編號，並可設定前綴與位置
- PDF 多頁合一排版 — 將 2 頁或 4 頁 PDF 排在同一張紙上
- PDF 轉圖片 — 將 PDF 頁面輸出為 JPG 或 PNG 圖片
以上步驟全部在這個頁面內完成，PDF 壓縮 不需要註冊、不上傳檔案、也不經過伺服器，關閉分頁後不會留下任何資料。