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.
Réponse courte
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 fait tout cela sur votre iPhone : numérisation en PDF net, OCR exécutée sur l'appareil et verrouillage des fichiers par Face ID – une app à achat unique, sans abonnement. Consultez la fiche App Store pour les fonctionnalités actuelles.
À vérifier avant de choisir
- 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
Un processus de décision pratique
- 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.
Comparaison rapide
| Besoin | Ce qu’il faut vérifier | Pourquoi c’est important |
|---|---|---|
| Modèle tarifaire | Vérifiez si les fonctionnalités utiles exigent un abonnement, un déverrouillage par achat unique ou ni l’un ni l’autre. | L’app la moins chère le premier jour n’est pas forcément la moins chère après un an. |
| Modèle de confidentialité | Privilégiez le traitement sur l’appareil lorsque le contenu est sensible. | Les documents privés, CV, données d’étude et contenus familiaux méritent une gestion attentive. |
| Export / verrouillage propriétaire | Vérifiez les formats de fichiers, le partage, la sauvegarde et les options de suppression. | Une bonne app doit vous aider à terminer la tâche, pas enfermer votre travail. |
Quand ScanTo Pro est adapté
ScanTo Pro convient bien si vous voulez numériser de façon privée, sur l'appareil et sans abonnement.
Achat uniqueSans abonnementSur l’appareil
Ceci est un guide d'achat rédigé et publié par le développeur de l'app. Les fonctionnalités et les prix sur l'App Store pouvant évoluer, veuillez vérifier les détails sur la page du produit avant tout achat.
FAQ
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.