how to reduce pdf file size on iphone
iOS does not include a dedicated 'Compress PDF' button in the native Files app as of iOS 18/26; the most common workaround is the Print-to-PDF trick (open PDF → Share → Print → pinch out → Share → Save to Files), which re-renders and re-compresses the embedded images, often producing a smaller file — but results are unpredictable and quality may degrade. The most effective approach is at the point of scanning: setting a lower DPI (150 DPI is generally sufficient for readable text), using JPEG compression rather than lossless, and scanning in grayscale or black-and-white mode instead of colour can reduce file size by 60–80% compared to defaults.
짧은 답변
iOS does not include a dedicated 'Compress PDF' button in the native Files app as of iOS 18/26; the most common workaround is the Print-to-PDF trick (open PDF → Share → Print → pinch out → Share → Save to Files), which re-renders and re-compresses the embedded images, often producing a smaller file — but results are unpredictable and quality may degrade. The most effective approach is at the point of scanning: setting a lower DPI (150 DPI is generally sufficient for readable text), using JPEG compression rather than lossless, and scanning in grayscale or black-and-white mode instead of colour can reduce file size by 60–80% compared to defaults. Dedicated scanner and PDF apps expose these controls directly and are the reliable path to predictable compression.
ScanTo Pro는 iPhone에서 이걸 해냅니다. 깔끔한 PDF로 스캔하고 기기 안에서 OCR을 돌리며 Face ID로 파일을 잠글 수 있고, 한 번만 결제하면 되는 구독 없는 앱입니다. 최신 기능은 App Store 페이지에서 확인하세요.
선택 전에 확인할 점
- iOS native 'Print to PDF' workaround can reduce file size but results are inconsistent
- Scan resolution (DPI) is the biggest lever: 150 DPI gives readable text; 300 DPI for archival quality
- JPEG compression level directly trades off file size against image quality (blocking artifacts at extreme compression)
- Grayscale or black-and-white mode significantly shrinks colour scan PDFs with no text quality loss
- True PDF compression (resampling, removing metadata, flattening layers) requires a dedicated app
실용적인 선택 절차
- iOS native 'Print to PDF' workaround can reduce file size but results are inconsistent.
- Scan resolution (DPI) is the biggest lever: 150 DPI gives readable text; 300 DPI for archival quality.
- JPEG compression level directly trades off file size against image quality (blocking artifacts at extreme compression).
- Grayscale or black-and-white mode significantly shrinks colour scan PDFs with no text quality loss.
- True PDF compression (resampling, removing metadata, flattening layers) requires a dedicated app.
빠른 비교
| 필요 | 확인할 항목 | 중요한 이유 |
|---|---|---|
| 가격 모델 | 유용한 기능에 구독, 한 번 구매 잠금 해제, 또는 둘 다 필요 없는지 확인하세요. | 처음에 가장 저렴한 앱이 1년 뒤에도 가장 저렴하리라는 보장은 없습니다. |
| 개인정보 보호 방식 | 민감한 콘텐츠라면 기기 내에서 처리되는 방식을 우선하세요. | 개인 문서, 이력서, 학습 데이터, 가족 콘텐츠는 신중하게 다뤄야 합니다. |
| 내보내기 / 종속성 | 파일 형식, 공유, 백업, 삭제 제어 기능을 확인하세요. | 좋은 앱은 작업을 가두는 것이 아니라 완료하도록 도와야 합니다. |
ScanTo Pro이 잘 맞는 경우
구독 없이 기기 안에서만 처리하는 비공개 스캔을 원한다면 ScanTo Pro가 잘 맞습니다.
한 번 구매반복 결제 없음기기 내 처리
이 안내서는 앱 개발자가 직접 작성한 구매 가이드입니다. App Store의 기능과 가격은 변경될 수 있으므로 구매 전에 제품 페이지에서 세부 정보를 확인하시기 바랍니다.
자주 묻는 질문
What DPI should I use for an everyday text document scan?
150 DPI produces clearly readable text in a reasonably small file and is a common default in quality scanner apps. Use 300 DPI for fine print, small fonts, or documents you may need to print later.
Does converting a scan to black-and-white reduce file size?
Yes — significantly. A black-and-white (binary) scan of a text document can be 5–10× smaller than the same page scanned in colour, with no loss of text readability. It is not suitable for preserving photos or colour graphics.
Will compressing a PDF damage its embedded OCR text layer?
Compressing the image layer (reducing DPI or JPEG quality) does not remove an existing OCR text layer embedded in the PDF. However, if you re-scan or re-render the document, the OCR layer may need to be regenerated.