Plenty of small business pages end with a button: “Download our brochure”, “See the price list”, “Read the menu”. Behind it there is often a PDF made for print, full of high-resolution photos. A website carbon test of that page may look healthy while the brochure itself is several times heavier than the page. This article explains why the test leaves downloads out, why they still matter, and how to make them lighter or replace them with something better.
Why the test doesn't count your downloads
A GreenTracer check measures one initial, uncached load of the page itself, using Google PageSpeed Insights on mobile and desktop. The test doesn't scroll or click. A link to a PDF is just a link: the file isn't fetched until someone clicks it, so it isn't part of the page load and isn't in your estimate.
There is one exception worth knowing about. If a PDF is embedded in the page, for example shown in a viewer that loads as the page opens, then it is downloaded during the load and is counted like any other file. If your result is surprisingly heavy, check whether a document viewer is the reason. Our article on reading a carbon report explains what the test includes in more detail.
But each download is still data
Leaving a file out of the page estimate doesn't make it free. The Sustainable Web Design Model, which GreenTracer uses, is described by its authors as suitable for many digital activities, including file downloads, because it works from the amount of data transferred. Using the same rate as our page estimates (about 0.148 g CO₂e per MB with the global average grid), a 10 MB brochure would be estimated at about 1.5 g each time someone downloads it: roughly ten times a 1 MB page view. These are illustrative figures, not a measurement of your file.
The difference is who pays and how often. A page is loaded by every visitor; a brochure only by the people who want it. But those people are often the keenest ones, sometimes on a phone with a limited data plan, and a large file is a slow, awkward start to a conversation with a likely customer.
When a web page is better than a PDF
The UK government publishes a great deal of information and has written clear guidance on this. Its page on publishing accessible documents says HTML is the most accessible format for documents, that a new PDF should be a last resort, and that a PDF should always come with an HTML version. It also notes that PDFs cannot be made fully accessible to all users of assistive technology.
A 2018 Government Digital Service blog post gives the reasons in more detail: PDFs are harder to find, use and maintain; they usually need zooming and scrolling on a phone; they are harder to update once published; and copies saved offline may go out of date. For a small business, those points translate simply:
- Price lists, menus, opening times and service details change often and are read on phones. They work better as an ordinary web page, which you can update in minutes and which people can find and read without a separate download.
- Forms people fill in are usually easier as a web form or a simple email request than as a PDF to print and scan.
- Documents meant to be printed or kept, such as a formal brochure, terms and conditions, or a signed specification, can reasonably stay as PDFs, ideally with the key information on a web page as well.
Keeping the PDFs you need lean
If a PDF is heavy, start with the photos in it. The common office tools offer settings for this when you export:
- Microsoft Office. When saving as PDF, Microsoft's instructions say to choose “Minimum size (publishing online)” if file size matters more than print quality. In Word, the same options include “Document structure tags for accessibility”, which helps screen-reading software.
- LibreOffice. The PDF export options include JPEG compression with a quality setting and “Change image resolution”, which down-sizes images. The help page also notes that tagged PDF can increase file size a lot. Keep tags on anyway if the document is public: accessibility matters more than a few extra kilobytes.
- Keep a print version and a web version. If your designer supplies a print-ready file, ask for a separate web export too. The print file can stay with your printer; the website gets the lighter one.
- Shrink the photos before they go in. The advice in our guide to image weight applies to documents too: a photo doesn't need to be much wider than it will appear.
After exporting, check the file size before uploading it. If a two-page leaflet is several megabytes, the images are almost certainly larger than they need to be.
Make downloads a choice, not a surprise
A good habit is to tell people what they are about to download, for example “Price list (PDF, 300 KB)”. It helps visitors on mobile data decide, and it keeps you honest about file sizes. Put the essentials on the page itself so that most visitors don't need the download at all, and remove old files that are no longer linked or are out of date.
Then check the page to see what the page itself sends, and look at its grade on our grades page. The downloads are yours to manage separately, and now you know how.
