Making a PDF small enough to email

Start by finding out why the file is large

Most of a PDF’s weight comes from the pictures inside it. A report or a spreadsheet saved as PDF is mostly text and lines and stays light, while a scanned document or a stack of phone photos is a bundle of large images and can reach tens of megabytes.

Knowing this makes the choice simple. Text-based files improve with a tidy-up of their structure, but picture-based files shrink noticeably only when the images are redrawn.

For example, a PDF made of ten photos that weighs 40 MB means about 4 MB per picture. A file like that is hard to bring under a limit just by tidying its structure.

What ‘Basic’ and ‘Strong’ each do

‘Basic’ reorganizes the file’s structure and drops resources that no page uses. Text and pictures are not re-created, so sharpness and searching stay as they were, though an already compact file may shrink only a little.

‘Strong’ redraws every page as a lower-resolution picture and builds a new PDF from them. A scan or a photo-heavy file shrinks the most this way, but afterward you can no longer select, search or copy the text on those pages.

Trying ‘Basic’ first and moving to ‘Strong’ only if the result falls short loses the least. Results from the two modes do not stay in separate rows, so note the numbers and compare them.

Step by step: shrink and check

Add one or more PDFs with ‘Choose files’, pick a mode under ‘Compression’ and press ‘Compress PDF’. Each row shows the old size, the new size and the percentage saved. Use ‘Download’ for one file or ‘Download all (ZIP)’ for several.

If the result is still too large, switch to ‘Strong’ and press the button again. Every run starts from your original file, so an earlier attempt never lowers the quality of the next. Each row also has its own download icon.

When you compare sizes before and after, go by the numbers shown on each row, not by impression. Some files drop below half their size without any visible change, while others lose sharpness after only a small saving.

• Add PDFs, and more with ‘Add more’ if needed
• ‘Basic’ for documents, ‘Strong’ for scans and photos
• Press ‘Compress PDF’ and compare the sizes
• ‘Download’ or ‘Download all (ZIP)’

Which mode for which file

Contracts and reports saved from a word processor should go through ‘Basic’ first, since the lettering stays crisp and searchable. If the result fits the limit, you are done.

A scanned paper or a PDF built from photos often barely shrinks with ‘Basic’, so it is quicker to start with ‘Strong’. The trade-off is that small print and thin lines can soften, which makes the checking step matter.

With many documents, one pass is convenient, but if the limits differ, look at the size of each result and redo only the files that need ‘Strong’.

What to know before using ‘Strong’

‘Strong’ redraws each page at a resolution that is comfortable to read on a screen. It may not suit paperwork you will print or plans with tiny lettering, so open a page or two and read them before sending.

Because the pages become pictures, links, form fields, bookmarks and the text layer disappear. If you need searchable text again, run the result through PDF OCR. Keeping the original somewhere safe is wise.

When you have a target size

There is no setting for a target such as ‘under 1 MB’. You pick a mode and judge from the size shown. If the limit is tight, try ‘Strong’ first.

If it is still over, Split PDF lets you cut the file into shorter parts and send them in several messages. As for order, compress first and sign afterward whenever a signature is needed.

If you are only just over the limit, remove pages you do not need first. Look for a cover sheet, blank pages or duplicate copies. With fewer pages the file often fits without switching modes.

Signed files need the right order

Compressing a PDF that carries a certificate-based digital signature rewrites the file, and the signature stops being valid. Do not compress a document that has already been signed that way; compress it first and sign it afterward.

A signature added as a picture is compressed like any other image and may only change in size, so a quick look for sharpness before sending is enough.

Mail services set different attachment limits, and the receiving side’s limit may be lower than yours. Checking the other party’s limit before sending helps you avoid a bounce.

Where your file goes

Compression runs in your browser and the PDF does not leave your device. There is no sign-up and no watermark. The result is a new file to download and your original stays as it is, but the names can match, so keep them in different folders or rename one.

What to confirm just before sending

Open the compressed file and read the first page, the last page and a page with small print. If you can read it comfortably, the recipient almost always can too.

Put a hint in the file name that it is the compressed version so it never gets mixed up with the original. After sending, open the message in your sent folder once to make sure the attachment really arrived.