Frequently Asked Questions

Question: What image formats does it support?

Answer: JPG to PDF online converter supports image formats JPG, PNG, GIF, BMP and TIFF directly. It also indirectly supports more than 100 other image formats such as SVG, HEIC, WEBP or JXR etc. These image files will be automatically converted to JPG files after uploading.

For full list of image formats it supports. Check at



Question: Which conversion engine should I choose?

Answer: We recommend using the default "APP Conversion Engine" if you like our JPG to PDF Converter app or need the output file size to be optimized. Smaller PDF file is easier to be uploaded online or sent by email. The "Exclusive Conversion Engine" supports more image formats such as animated GIF or multi-page TIFF etc. This conversion engine doesn't optimize output file size. You can choose "Open-source Conversion Engine" if you want the image in PDF is exactly the image before conversion without any optimizing or shrinking. You can try all three conversion engines to find out which one you should use.


Question: How many image files can I convert?

Answer: You can add as many image files as you want in your PDF, as long as each image file size is less than 40mb. However each file conversion takes 528m memory at max and it is forced to be finished in 6 minutes. The conversion will be automatically terminated when time is up.

You can convert partial images each time if you have too many images to convert, then merge the output PDF files online.


Question: Is it safe to convert images on

Answer: Yes, it's safe to convert images on All your files are treated as strictly confidential. All file transmissions are through HTTPS instead of HTTP. Your files will be saved to a directory with random 10 characters so only you can find it.

Your files are only temporarily stored on our servers for 1-2 hours, after that they will be automatically deleted by a scheduled program. You can see "Deletion Countdown" on conversion result page.


Question: What's the maximum PDF page size?

Answer: The maximum PDF page size is 14400 by 14400 units (200 by 200 inches) if you only convert one single image file. However the maximum page size will start to decrease when file number starts to increase. For example: the maximum PDF page size will be 5328 by 5328 units when there are 5 image files; the maximum page size will be A4 (595 by 842 units) when there are more than 30 image files. This is a compromised method to prevent OOM (Out Of Memory) error on server.

Your image will be resized if its size is bigger than the maximum PDF page size.


Question: How to reduce PDF file size?

Answer: There are two ways to reduce output file size.

1: Set a smaller PDF page size. The default PDF page size is your image size. You can choose preset page size such as A4 Portrait/Landscape or choose "Custom Size" and enter page width and height.

2: Compress JPG images. You can select "Enable PDF compression" option and enter JPG quality to compress JPG images. This will significantly reduce PDF file size.


Question: How can I convert JPG to PDF offline?

Answer: We strongly recommend our JPG to PDF Converter app for Android. This online converter is designed to work just like our JPG to PDF Converter app. They have the same PDF compression, protection and page size settings. Unlike the online converter, all functions in JPG to PDF Converter app can be used offline.