Journal-level metrics measure the impact, reach, or prestige of a journal. Journal-level metrics are designed to measure the aggregate impact of publication as a whole and should not be used as proxy metrics for authors who publish in a particular journal.
There are two main sources of Journal Metrics.
To find the journals with the highest impact in Web of Science, use Journal Citation Reports which lists the Journal Impact Factor of all journals. The Journal Impact Factor is calculated by dividing the number of citations in the Journal Citation Reports year by the total number of articles published in the two previous years. A Journal Impact Factor of 1.5 for a particular journal would mean that, on average, articles published in that journal during the previous two years have been cited 1.5 times. The Journal Impact Factor is a relative number and can only be used to compare journals in the same research field. The Journal Impact Factor uses Thomson Reuters’s Web of Science citation data.
When choosing a journal an important factor to consider is its ranking in its subject category or categories e.g. whether it is ranked in the top 10 journals in the subject category by impact factor or whether it is a quartile 1 or quartile 2 journal. In the journal profile page in Journal Citation Reports for the journal of interest in, click on Ranking on the left hand side below the Key Indicators box. If the journal is included in more than one subject category remember to scroll to the right in the Ranking window to see its ranking in the other categories.
SNIP (source normalized impact per paper) is also available at www.journalindicators.com and via Scopus and uses citation data from Scopus. This indicator measures the average citation impact of the publications of a journal. The SNIP corrects for differences in citation practices between scientific fields, which allows for more accurate between-field comparisons of citation impact.