Journal-level metrics measure the influence and research impact of journals. The measures are predominately based on citation counts. Journal metrics are used by researchers to identify the most appropriate and influential journals in which to publish and to track citation patterns to make strategic and funding decisions.

• Useful for understanding past publishing behaviour and for developing and monitoring future publication strategy; never as a proxy for the impact or quality of an individual article.
• The relationship between a journal’s citation impact and the rigour of its peer-review process is unclear. 
• The citation impact of a journal must never be used as a proxy for the value of a given paper in  research evaluation: but the two are often conflated. 
• An article in a top journal may remain uncited for many years, so publication in a high impact journal doesn’t necessarily mean that an article must be highly cited as well.

The following are the key resources where you can obtain journal-level metrics.

• Scopus
• CWTS Journal Indicators
• SCImago Journal Rankings
• Google Scholar