How to Scan Documents to PDF with Your Phone
Your phone's camera is sharper than most office scanners. What it lacks is a flat glass bed and even light, which is why phone "scans" often come out tilted, shadowed and huge. With a bit of technique and a scanning tool that straightens and cleans the image, you can produce scans that are as good as a flatbed's and small enough for any email or portal.
Before you press the shutter
Light
Light is the single biggest factor. Daylight from a window, falling across the page from the side, is ideal. Avoid:
- A ceiling light directly above, which casts the shadow of your phone and hand on the page.
- The phone's flash, which creates a bright spot and glare, especially on glossy paper and laminated cards.
- Mixed lighting (yellow bulb plus daylight), which tints parts of the page.
Surface
Put the document on a dark, plain surface: a dark table, a bed sheet or a file folder. The contrast between dark background and white paper helps the scanner find the page edges automatically. Flatten folded documents; put a book on them for a minute if you can. For a bound book, press the spine down gently.
Angle
Hold the phone parallel to the page, directly above it, with the whole page in view and a little margin around it. Leaning helps avoid your shadow, and the perspective correction can fix moderate tilt, but extreme angles make the far edge of the page lower in resolution.
Clean the camera lens. A fingerprint smudge makes everything look hazy, and it is the most common reason a scan looks soft.
Scanning with Scan to PDF
- Open Scan to PDF on your phone's browser and tap Take photo. You can also add existing photos.
- The tool finds the page's corners and flattens the perspective. If it cannot find them ("Edges not found — tap to crop"), drag the four corner circles onto the page corners yourself; a magnifier shows the exact spot.
- Keep shooting for more pages. Drag pages, or use the arrows, to put them in order.
- Choose a filter for each page or apply one to all pages.
- Choose the output quality and download the PDF.
Which filter?
| Filter | What it does | Use for |
|---|---|---|
| Original | Colours as photographed | Photos, coloured certificates where the colour matters |
| Clean | Evens out light so paper turns white | Most documents; a good default |
| Black & White | Pure black text on white | Typed letters, forms, receipts; smallest files |
| Grayscale | No colour, keeps shades | Documents with pencil, faint stamps or photos in them |
Black & White is tempting because it looks crisp, but it can make faint stamps, signatures in light ink and photographs disappear or turn blotchy. For certificates with a coloured seal or a passport-type photo on them, use Clean or Grayscale.
Quality and file size
Scan to PDF offers Standard (smaller files) and High (300 dpi). Standard is fine for screen reading, email and most portal uploads. Choose High for documents you may need to print, or with very small text.
Some useful reference points:
- A Black & White page at Standard is usually small enough for strict portal limits.
- A colour page at High can be several hundred KB to a few MB.
- Email attachments usually have a 20–25 MB limit, which is rarely a problem for a few pages.
If the PDF still exceeds a portal's limit, use Compress PDF with a target size, as explained in our guide to reducing PDF size for government portals.
Name your files sensibly
Scanned PDFs land in Downloads with names like "scan-1.pdf". Rename them straight away to something that says what they are, for example "Ravi_Kumar_10th_Marksheet.pdf". Officers handling uploads, and you yourself six months later, will thank you. Keep names short and use only letters, numbers, hyphens and underscores, because some older portals reject spaces and special characters.
Multi-page documents
- Scan pages in order, front then back, so you do not need to rearrange later.
- Skip blank backs of pages. They add size and confuse readers.
- If pages end up in the wrong order after combining scans from different sessions, fix them in Reorder.
- For two-sided ID cards, put front and back on one page if the recipient asks for it, or as two pages otherwise.
OCR: what to expect
A scan is a picture of text. Unless OCR (optical character recognition) is run on it, you cannot search for words, copy text or have a screen reader read it. Scan to PDF produces image-based PDFs: perfect for submitting copies of documents, but not searchable.
When you do need the text, OCR quality depends on the scan. Clean, straight, well-lit, 300 dpi scans of printed text give good results. Handwriting, low-light photos, curled pages and decorative fonts give poor ones. Expect to proofread any OCR output, especially numbers, which are easy to misread (0 and O, 1 and l, 5 and S).
For understanding long documents rather than extracting text, Chat with PDF lets you ask questions about a document in the browser. It works best with PDFs that already contain text.
Common problems
- Edges not detected. Low contrast between page and background. Put the page on a darker surface, or crop by hand.
- Grey or uneven background. Use the Clean filter, and next time improve the light.
- Text looks wavy. The paper was not flat. Flatten it and rescan.
- Blurry text. Lens smudge, hand shake or too close. Tap to focus, hold steady, and step back a little.
- Glare stripe on laminated cards. Turn off the flash and tilt the card slightly away from the window.
- File too big. Use Standard quality and Black & White or Grayscale.
Special cases
ID cards and small documents
For Aadhaar, PAN or driving licence cards, move the phone closer so the card fills most of the frame, and use High quality: the text is tiny. If you need both sides on one A4 page, many offices accept two pages instead; ask before spending time on a layout.
Receipts and long bills
Thermal-paper receipts fade and curl. Flatten them under a book, scan in Grayscale rather than Black & White, and scan soon, before the print fades.
Photographs and colour documents
Use Original. The Clean and Black & White filters are designed for text on paper and will flatten a photograph.
Privacy
Scans of IDs, medical reports and bank documents are sensitive. Scan to PDF processes the photos in your browser; nothing is sent to a server. Afterwards, consider deleting the raw photos from your phone gallery and cloud photo backup if you do not need them there.