Scanning receipts and documents with your phone: PDF, JPG or PNG?
Expense claims, rental applications, insurance claims, visa forms, school enrolments: a lot of life now involves uploading a “clear copy” of a document. Most people no longer own a scanner, and a phone camera is more than good enough, provided the photo is taken with a bit of care and saved in a sensible format.
Getting a good capture
Most scanning problems start at the moment of taking the photo, and no converter can fully fix them afterwards.
- Light it evenly. Daylight from a window is ideal. Overhead lights tend to cast the shadow of your phone and hand across the page. Avoid the flash, which leaves a bright hotspot.
- Hold the phone parallel to the page. Shooting at an angle turns rectangles into trapezoids and makes the far edge blurrier.
- Use a contrasting background. White paper on a dark table makes the edges easy to see and crop.
- Fill the frame, but leave a small margin so nothing is clipped.
- Tap to focus on the text and check the photo by zooming in before moving on.
Both major phone platforms include document scanners that straighten pages automatically: the Notes and Files apps on iPhone, and the scan feature in Google Drive on Android. They are worth using for multi-page documents. For a single receipt, a careful photo and a crop works just as well.
Choosing the format
PDF: for anything with more than one page, or anything formal
PDF keeps pages in order, opens on every device, prints at the right size, and looks like a proper document to whoever receives it. If a form asks for a bank statement, a lease or a set of payslips, send a single PDF rather than a scatter of images. Photos can be turned into one with JPG to PDF, with each page on an A4 sheet if the recipient is likely to print it.
JPG: for single pages when an image is requested
If the upload box asks for an image, or accepts one page at a time, JPG is the safe answer. It keeps files small, and at a quality of 80 to 85 text stays perfectly readable. Receipts, ID cards and single forms are typical.
PNG: for clean black and white
If a document is pure black text on white, converting it to black and white and saving as PNG gives a very crisp, very small file. It is the best-looking option for signatures, typed letters and forms. It is a poor choice for anything with photos, coloured stamps or shaded backgrounds, which become harsh blobs.
How much resolution is enough?
For text, around 200 pixels per inch of paper is plenty, and 150 is usually enough for normal-sized print. An A4 page at 200 PPI is about 1650 × 2340 pixels. A modern phone captures far more than that, so a straight phone photo is often 3 to 5 MB, and a ten-page PDF of phone photos can easily be 40 MB.
Many upload systems cap files at 2, 5 or 10 MB. The quickest way under the limit is to reduce the pixel dimensions: a long edge of 2000 to 2500 pixels keeps A4 text sharp. Then compress. The JPG compressor can do both in one pass.
Converting to greyscale also helps a little for documents where colour does not matter, and makes the page look cleaner.
Keep sensitive documents close
Documents tend to carry the most sensitive information you own: account numbers, tax file numbers, dates of birth, signatures, passport details. Think twice before running them through a website that uploads your files to a server to convert them. Tools that work entirely in your browser avoid that step.
When sending copies of ID, consider adding a watermark stating who it is for and the date, such as “Copy for XYZ Rentals, September 2026”. It does not stop the recipient using it, but it makes a leaked copy much less useful to anyone else. And where only part of a document is needed, cover the rest; a solid box over an account number you were not asked for is a reasonable precaution.
A quick routine
- Photograph each page flat, in good light.
- Crop to the page edges.
- For text-only pages, convert to greyscale or black and white.
- Resize to about 2000 pixels on the long edge.
- Combine multi-page documents into one PDF; send single pages as JPG.
- Check the result by zooming in on the smallest text before you send it.