How do I fax double sided?

Last Update: August 9th, 2021

Faxing double-sided can be tricky.

In most cases, it can only happen with a fax machine with a document feeder (usually found on higher-level corporate equipment), or through computer-based fax such as fax software or an online fax service.

Understanding fax and “sides”

Fax can’t be “transmitted” double-sided. All faxes are “sent” as a single-sided document.

It is the physical fax machine that changes the single-sided document to double-sided (or the other way around if receiving the fax).

There is no encoding to say “make this fax transmission double-sided” or “make this fax single sided.”

Sending a fax

… from a double-sided document

To send a fax from a double-sided document, your options are:

1) Use fax machine with a duplex document feeder (one that can read both sides of the page).

Duplex document feeders are normally used on commercial level equipment (such as a multifunction printer/scanner/copiers).

Some entry-level office equipment without an auto-duplexing scanner but with the ability to do a software duplex will work as well. A software duplex is when the document is put into the document feeder and scanned, then put oppositely and scanned again. The software in the equipment then mixes the pages into the proper order to send the document.

Check your user manuals to find out if your equipment has this feature. It is relatively rare.

2) Use a software-based faxing system (one such as fax software, an online fax service, or an advanced printer driver)

Many software-based faxing systems such as an online fax service or fax software will let you scan and pre-check your document. These systems will let you make sure the pages are in order, and may automatically collate a scanned document from a single-sided fax machine.

There is also the convenience of being able to fax over email, a computer, or smartphone.

3) Copy and print out the second side of the document and mix the pages into the right places with the original document.

This is time-consuming but gets the job done. If without a printer, most fax machines can do a simple one-sided copy function.

Alternatively, you can copy the 2nd side of the document and attach it to the end of the original document. This will send all the pages, but they will be in a mixed up order. Some people receiving the document may consider it to be sent in error.

… to be received double sided

When sending a fax, there is no way to designate whether the receiving fax machine will print it as single sided or double sided.

It is up to the receiving fax machine to determine how the document pritns. Even a cover sheet marked with “print double sided please” will not help, as the cover sheet is part of the transmitted document and isn’t read until the entire fax prints.

…from a double-sided document to be received as double sided

When sending a fax there is no way to designate whether the receiving fax machine will print it as single sided or double sided.

See above for more on sending a document that is currently double sided.

Receiving a fax double sided

It is impossible for a receiving fax machine to understand whether the document was one-sided or two-sided. It can, however, print the document out as a two-sided document if the fax machine has those capabilities.

… from a single-sided document

To print a fax as a double-sided document, you will need a fax machine with a duplexing printer.

These are usually found in commercial level equipment, such as multifunction copier/printer/scanners with a fax feature.

Check the user manual to set the faxes to print to double-sided automatically.

A best practice is to make sure that there is also the ability to send faxes double sided – many people use fax as a quick way to receive a document, sign it, and send it back through the fax. While saving paper is good, without the ability to fax back a double-sided document it can create a lot of user frustration and potentially missent documents.

… from a double-sided document

There is no way to designate whether the sent document was initially single-sided or double-sided.

If receiving a document that the sender said was sent as double-sided, it is essential to verify the document to make sure that no pages are missing and that pages are in the proper order.

The fax cover sheet should include the total number of pages in the fax transmission.

Sources and more resources

AZ Central Your Business – How to fax pages with both sides – A quick how-to on how to send double-sided pages as a fax.

Epson Support – Two-sided Printing, Scanning, Copying, and Faxing – Epson’s instruction on how to fax a two-sided document.

HP Support Forums – Sending a 2 sided fax – A forum discussion on how to send 2 sided faxes on HP equipment.

Brother – How can I send a two-sided fax from my Brother machine? (duplex faxing) – Step by step instructions on sending a two-sided fax with a Brother fax machine.