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.
Jawapan ringkas
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 Pro does this on your iPhone: it scans to a clean PDF, runs on-device OCR, and can lock files with Face ID — a pay-once app with no subscription. Check the App Store listing for current features.
Apa yang perlu dipertimbangkan sebelum memilih
- 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
Proses membuat keputusan yang praktikal
- 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.
Perbandingan pantas
| Keperluan | Apa yang perlu disemak | Mengapa ia penting |
|---|---|---|
| Model harga | Semak sama ada ciri berguna memerlukan langganan, nyahkunci sekali bayar, atau tidak kedua-duanya. | Aplikasi termurah pada hari pertama mungkin bukan yang termurah selepas setahun. |
| Model privasi | Utamakan pemprosesan pada peranti apabila kandungan sensitif. | Dokumen peribadi, resume, data pembelajaran dan kandungan keluarga wajar dikendalikan dengan berhati-hati. |
| Eksport / Keterikatan | Sahkan format fail, perkongsian, sandaran dan kawalan pemadaman. | Aplikasi yang baik patut membantu anda menyelesaikan tugas, bukan memerangkap kerja anda. |
Di mana ScanTo Pro sesuai
ScanTo Pro is a strong fit when you want private, on-device scanning without a subscription.
Bayar sekaliTanpa langgananPada peranti
Ini ialah panduan pembelian yang diterbitkan oleh pembangun app itu sendiri. Ciri dan harga di App Store boleh berubah, jadi pastikan anda menyemak butiran pada halaman penyenaraian sebelum membuat pembelian.
Soalan Lazim
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.