SNIP 1.556 2014 2015 2016 2017 2018
  • 3584
  • 985
  • 3643
  • 989
  • 3587
  • 1011
  • 3554
  • 1030
  • 3968
  • 1017

About SNIP

Source-Normalized Impact per Paper (SNIP) measures the impact of a paper within a subject field.


Year SNIP Citations Papers
2018 1.556 3968 1017
2017 1.436 3554 1030
2016 1.554 3587 1011
2015 1.626 3643 989
2014 1.699 3584 985



Source-Normalized Impact per Paper (SNIP) measures contextual citation impact by weighting citations based on the total number of citations in a subject field. This unique perspective enables direct comparison of sources in different subject fields. The impact of a single citation is given higher value in subject areas where citations are less likely, and vice versa.

It is a ratio, with a numerator and a denominator. SNIP's numerator is a journal's impact per publication (IPP). This is simply the average number of citations received in a particular year (e.g. 2013) by papers published in the journal during the three preceding years (e.g. 2010, 2011 and 2012).

SNIP's denominator is the Database Citation Potential (DCP). We know that there are large differences between various scientific subfields in the frequency at which authors cite papers. In view of this, for each journal an indicator is calculated of the citation potential in the subject field it covers. This citation potential is included in SNIP's denominator, the DCP. SNIP is IPP divided by DCP.

SNIP enables direct comparison of sources in different subject fields. Citation potential is shown to vary not only between journal subject categories (groupings of journals sharing a research field) or disciplines (e.g., journals in Mathematics tend to have lower values than journals in Life Sciences), but also between journals within the same subject category. For instance, basic journals tend to show higher citation potentials than applied or clinical journals. Likewise, journals covering emerging topics tend to be higher than periodicals in classical subjects, or more general journals.

SNIP helps authors to identify which journals are performing best within their subject field, helping them decide where to publish. Mouse over the circles in the visualization and click on the year to view the journal's metrics. The size of the circles are compared to the highest values in the 5-year range. This highest value is represented by a closed circle, and the open circles indicate the journal's value compared to this highest value.

See Journal Metrics site for background info and more datasets.