A visa portal, a landlord or an insurance claim form asks for "one PDF". What you have is five phone photos of a signed lease, a picture of both sides of an ID card and a receipt you snapped at the counter. The upload field refuses loose images, or it takes only one file, and emailing eight attachments in random order is how pages go missing.
Putting the photos into a single PDF solves all of that, but three choices decide whether the result looks like a proper document or a pile of oversized pictures: the page size, the page order and the file size. This guide explains each one, with the numbers behind them, and covers the cases where a PDF of photos is not what the recipient needs.
TL;DR: A PDF made from photos holds one image per page, in an order you set, and opens the same way on every device. Choose A4 or US Letter for anything that will be printed or submitted, because "fit to image" makes each page as many points wide as the photo has pixels (a 4,032-pixel phone photo becomes a 56-inch page). Expect the PDF to be roughly the combined size of the photos; shrink the photos first if a portal caps the upload. The JPG to PDF converter does this client-side, nothing uploaded, free, no signup, and the PNG to PDF converter does the same for screenshots without any lossy step.
What happens when a photo becomes a PDF page?
A PDF page made from a photo is a page of a set size with one raster image drawn on it. The PDF format, standardized as ISO 32000-2, describes a page as a rectangle measured in points, where one point is 1/72 of an inch, and an image as an object painted into that rectangle at some position and scale. The photo keeps its pixels; the page only decides how large they are drawn.
That separation matters. The same 4,032 by 3,024 pixel photo can sit on a page 56 inches wide or on an 11.7-inch A4 page. The image data inside the file is the same size either way. What changes is how the page looks in a viewer, how it prints and whether a document checker thinks it is a normal document.
The photo itself is stored in the PDF in a compressed form. JPEG compression, defined in ITU-T Recommendation T.81, is one of the filters PDF supports directly (it is called DCTDecode in the specification), so a photo can live inside a PDF as JPEG data. PNG-style lossless compression is also supported, which is how screenshots and graphics are usually stored.
Nothing in this process reads the words on the page. A photo of a letter becomes a picture of a letter. You cannot select, search or copy its text unless the PDF is later run through text recognition (OCR), which is a separate job.
How does the Toolz converter build the PDF?
The Toolz converter builds the PDF as soon as you add files, and rebuilds it whenever you change a setting. There is no Convert button to press. Add the photos, adjust the options, check the order, and press Download PDF when the PDF row shows it is ready.
Here is what happens to each photo along the way:
- The browser decodes the JPG into pixels. Images over 100 megapixels are refused with a message, because decoding them could crash the tab.
- The pixels are re-encoded as JPEG at 92% quality. PNG files added on the PNG to PDF page are encoded as PNG instead, so nothing is lost.
- Each image is placed on its own page with pdf-lib, an open source PDF library that downloads only once you add the first file.
- The pages are written in the order of the file list, and the PDF is offered as
images.pdf. A single photo keeps its own name, sopassport.jpgbecomespassport.pdf.
The 92% re-encode is a deliberate choice. It keeps the PDF close to the size of the photos you added while staying hard to tell apart from the original. It also means the photo passes through a canvas, so EXIF data, including the capture date, camera model and any GPS location, is not carried into the PDF. For a scan of an ID card, that is usually what you want.
If one file cannot be read, its row shows the reason and the PDF is still made from the others. The PDF records Toolz.dev as the program that produced it and nothing about you or your files.
Which page size should you choose?
Choose A4 or US Letter for any PDF that will be printed, attached to a form or checked by someone else. Choose Fit to image only when the PDF will be viewed on screen and the photos have different shapes you want to keep exactly.
The converter offers three sizes. This is how each one behaves:
| Page size | Page dimensions | How the photo is placed | Best for |
|---|---|---|---|
| Fit to image | Photo's pixels as points (1 pixel = 1 point = 1/72 inch) | Fills the page exactly, no scaling | On-screen viewing, mixed shapes |
| A4 | 595.28 x 841.89 points (210 x 297 mm) | Scaled up or down to fit, centered | Printing and forms outside North America |
| US Letter | 612 x 792 points (8.5 x 11 in) | Scaled up or down to fit, centered | Printing and forms in the US and Canada |
A4 is defined by ISO 216, the paper standard used across most of the world. US Letter is the North American standard. If you are not sure which one a portal expects, use the paper size of the country the form comes from.
Why "fit to image" pages are so large
Fit to image turns every pixel into a point. A typical 12-megapixel phone photo is 4,032 by 3,024 pixels, so its page is 4,032 by 3,024 points, which is 56 by 42 inches. A PDF viewer zooms to fit the window, so it looks normal on screen. Print it, or open its properties in a document checker, and it is a poster-sized page.
The PDF format has a practical upper limit too. Most viewers refuse pages larger than 200 inches (14,400 points) on a side, so the converter shrinks any fit-to-image page that would pass that limit.
Landscape and portrait in the same PDF
On A4 and US Letter, each page picks its own orientation. A photo wider than it is tall gets a landscape page; anything else gets a portrait page. A set that mixes upright shots of a document with a sideways photo of a whiteboard stays readable without rotating anything, and the PDF simply alternates orientation where needed.
Will the photos print sharply?
Almost always, if you start from the full-size photo. Print sharpness depends on how many pixels land on each inch of paper, often called pixels per inch (ppi). Around 300 ppi is the usual target for close reading; much below 150 ppi starts to look soft.
Here is the arithmetic for the converter's layout, using real page and photo sizes:
| Photo | Page | Margin | Drawn size on paper | Resulting ppi |
|---|---|---|---|---|
| 4,032 x 3,024 (landscape phone photo) | A4, landscape | None | 11.02 x 8.27 in | about 366 |
| 4,032 x 3,024 | A4, landscape | Small | 10.36 x 7.77 in | about 389 |
| 3,024 x 4,032 (portrait phone photo) | US Letter, portrait | None | 8.25 x 11.00 in | about 367 |
| 3,024 x 4,032 | US Letter, portrait | Small | 7.88 x 10.50 in | about 384 |
| 600 x 800 (thumbnail) | A4, portrait | None | 8.27 x 11.02 in | about 73 |
To check the first row by hand: the landscape A4 page is 841.89 by 595.28 points. The photo's 4:3 shape (1.33 to 1) is less elongated than the page's 1.41 to 1, so height is the limiting side. The scale is 595.28 / 3,024 = 0.1969, so the photo is drawn 793.7 points wide (11.02 inches) and 595.28 points tall (8.27 inches). Dividing 3,024 pixels by 8.27 inches gives about 366 pixels per inch.
The last row is the trap. Scaling works in both directions, so a 600-pixel image sent through a messaging app, which often shrinks photos, is stretched to fill the page and prints at about 73 ppi. Convert the original from your camera roll, not the copy you received in a chat.
What does the margin setting do?
The Small margin keeps a quarter inch (18 points, 6.35 mm) of white on every side of the photo. Many desktop printers cannot print the outer few millimeters of a sheet, so a photo that runs to the edge can lose a strip of text. The margin gives the printer room. For a PDF that will only be uploaded, None is fine.
How do you get the pages in the right order?
The PDF follows the file list from top to bottom. Files are listed in the order you add them, and each row is labeled Page 1, Page 2 and so on, so you can see where every photo will land before downloading.
To change the order, use the up and down buttons on a row. Each press moves that photo one place earlier or later, and the PDF is rebuilt in the new order. Files added later join at the end, and you can move them up from there.
A few habits save time with multi-page documents:
- Add pages in reading order in the first place. Most file pickers sort by name, and phone photos are named by capture time, so shooting pages in order usually means they arrive in order.
- For a two-sided ID card, add the front first. Many forms reject a card whose back comes first.
- Check the page count on the PDF row against the paper stack before downloading.
If the PDF is already downloaded and one page is out of place, you do not need to start again. The organize PDF tool reorders and rotates the pages of a finished file, and the guide to merging PDFs covers joining a new page onto a PDF you made earlier.
Why is the PDF so big, and how do you make it smaller?
A PDF of photos is roughly as large as the photos inside it, because it contains every one of them at full resolution. The page size does not change this. Choosing A4 instead of fit to image changes how big each photo is drawn, not how many pixels it has.
As a worked example, ten phone photos of around 3 MB each produce a PDF of around 30 MB. That is too large for many email servers and for portals that cap uploads at a few megabytes.
The effective way to shrink it is to reduce the pixel count of the photos before converting. Halving the width and height of a 4,032 by 3,024 photo to 2,016 by 1,512 leaves a quarter of the pixels, and JPEG file size falls roughly in line with that. From the table above, a 2,016-pixel-wide photo on landscape A4 still prints at about 183 ppi, which is readable for a document. The image resizer does that step client-side.
Two approaches that help less than people expect:
- Lowering JPEG quality before converting. Each photo is re-encoded at 92% on the way into the PDF, so a lower-quality input mostly gains you extra artifacts.
- Compressing the finished PDF. The Toolz compress PDF tool repacks the document structure without re-encoding images, so a PDF that is almost entirely photos shrinks very little. The compress PDF guide explains what it can and cannot remove.
JPG to PDF or PNG to PDF: which should you use?
Use JPG to PDF for photos and phone scans, and PNG to PDF for screenshots, charts, diagrams and anything with transparency. The difference is how the image is stored inside the PDF.
| Source | Stored in the PDF as | Quality | Transparency | Typical PDF size |
|---|---|---|---|---|
| JPG photo | JPEG at 92% quality | Very slight re-encode loss | None (JPG has none) | Close to the combined photos |
| PNG screenshot or graphic | PNG, lossless | Pixel for pixel | Kept; shows as white in most viewers | Close to, or larger than, the PNGs |
PNG, specified by the W3C PNG recommendation, is lossless, so small interface text and thin lines keep hard edges inside the PDF. A PNG of a photo, on the other hand, makes a very large PDF, and converting it to JPG first is the better route.
Each converter page accepts only its own format. Drop a PNG onto the JPG page, or a HEIC photo from an iPhone, and the page names the converter that handles it instead of converting it quietly. iPhone photos are HEIC by default; the HEIC vs JPG guide explains why, and the HEIC to PDF converter puts them straight into a PDF.
Is a PDF of photos good enough for official forms?
For most upload portals, yes. A PDF with one clear photo per page, on A4 or US Letter, in the right order and under the size cap, is what "scan and upload as a single PDF" normally means in practice. A few requirements go further, and it is worth checking the form's instructions for them:
- Searchable text. Some systems want text they can index. A photo-based PDF has none; the page is an image. That needs OCR software, which this converter does not run.
- PDF/A. Archives and some courts require PDF/A, the archival profile defined in ISO 19005. The PDF made here is a standard PDF, not a certified PDF/A file.
- Fillable fields. If you were sent a fillable PDF form, fill in that file directly. Photographing a printed copy and converting it throws the fields away.
- Color or grayscale rules. The converter keeps each photo's colors as they are. If a form asks for grayscale, convert the photos before adding them.
A good photo of the paper matters more than any setting in the converter, which is the subject of the next section.
How do you photograph documents so the PDF is readable?
The converter places each photo on a page exactly as it was taken, so the quality of the PDF is set when you press the shutter. A few habits make the difference between a page a reviewer can read and one they send back.
Lay the page flat on a dark, even surface. A dark background makes the edges of white paper obvious, and a flat page avoids the curved lines of text that come from photographing a document held in one hand.
Use daylight or even room light, and turn off the flash. A flash on glossy paper or a laminated card leaves a white glare spot that can hide a date or a signature. Move so that your shadow does not fall across the page.
Hold the phone parallel to the paper, directly above it. Tilting the phone turns the rectangular page into a trapezoid, with the far edge smaller than the near one. Fill the frame with the page, leaving a thin border of background so no edge is cut off.
Check each photo before converting. Zoom into the smallest text on the page; if you cannot read it on the phone, the reviewer will not read it in the PDF. Retake it rather than hoping the converter improves it, because nothing in the conversion sharpens, straightens or brightens a photo.
If your phone's camera app has a document scanning mode, it will flatten the perspective and crop the page for you. Those scans are usually saved as JPG or PDF already; when they are JPGs, they convert here like any other photo.
Is converting on Toolz private?
Yes. The conversion is client-side: your browser decodes each photo and writes the PDF inside the tab, and no photo or PDF is uploaded. That matters when the pages are passports, bank statements or medical letters.
Two small pieces of data do leave the page. The daily limit check sends the tool name and a device identifier, plus your account token if you are signed in. After a batch, the page records the file count, total bytes and output format, never file names or image data. The tool is free, no signup, with a daily limit on conversions. Photos and PDFs stay in the tab's memory until you remove them, press Clear All or close the page.
Alternatives to an online JPG to PDF converter
Both major desktop systems can make a PDF from photos without a website.
On Windows 10 and 11, select the photos in File Explorer, right-click and choose Print, then pick Microsoft Print to PDF as the printer. The print dialog offers paper sizes and a "fit picture to frame" option, which crops photos unless you untick it.
On a Mac, select the photos in Finder and open them in Preview. Arrange the thumbnails in the sidebar, then choose File, then Print, and use the PDF menu at the bottom of the dialog to save as PDF.
The browser route is the same on any system, needs no installation, and gives A4, US Letter, margin and per-image options in one place. For the reverse job, turning a PDF's pages back into images, the PDF to JPG converter renders each page as a JPG. Every converter in the set is listed on the image tools hub.
When the photos are ready, combine your JPGs into one PDF, pick the paper size of the country the form comes from, and check the page count before you upload.
