The equal contributions footnote specifies if two or more authors contributed to the manuscript equally. It would appear under the author byline on the PDF. If only some of the authors have the equal contribution designation, the footnote will say, "These authors contributed equally". If all of the authors have the equal contribution designation, the footnote will say, “All authors have contributed equally”.

When to use the equal contributions footnote

It is at the discretion of authors to determine what “equal” means and when authors’ contributions qualify for the footnote. This footnote can be quite ambiguous, as it doesn’t specify whether equal contribution indicates greater contribution or lesser contribution.

We recommend only using the equal contributions footnote to indicate if all authors contributed equally, or to indicate that the main authors (ie, first two authors or the first and last author) contributed equally. Rather than, or in addition to, using the footnote, we encourage adding a section titled “Authors’ Contributions” to the end of your manuscript to specify, in narrative form, how each author contributed. The only time when we do not recommend a narrative form of authors’ contributions is when all authors contributed equally. In this case, specify only with the equal contributions footnote.

Where to set the equal contributions footnote

When entering author information during submission or when editing the metadata after submission, there is a drop-down field to specify equal contributions with a footnote.

• If you wish to indicate that the main authors contributed a greater and equal amount, from the dropdown select “Yes” for the authors you wish to apply this attribution to and select “No” for the others.
• If you wish to indicate that all authors contributed equally, select “Yes” for all authors.
• If you do not wish to indicate equal contribution for any of the authors, select “Unspecified” for all authors. This is recommended in most cases.