impact factors for IUCr journals

Impact factors

Journal impact factors are published by Clarivate Analytics in the annual publication Journal Citation Reports (JCR). The latest impact factors are for 2021. The impact factors for IUCr Journals for the period 2000–2021 are summarised below.

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Impact factors
Acta Crystallographica Section A2.3312.2901.9601.8787.9305.7252.3332.3252.0692.2442.07654.3349.932.0512.3851.6761.7911.8291.5581.4171.7491.491
Acta Crystallographica Section B2.6842.2662.0486.7326.4672.0322.8922.1842.0952.1752.2861.8291.8012.3412.1632.1721.9105.4183.6432.0261.9551.734
Acta Crystallographica Section C1.1841.1721.0900.9308.6784.0990.4790.3260.5350.4920.5180.7450.7820.5610.7190.8960.7770.7280.8280.6590.5700.543
Acta Crystallographica Section D5.6997.6525.2663.2273.0992.1142.5122.6807.23214.10312.6196.3262.2572.9432.6201.6871.4011.6932.2081.7602.1243.067
Acta Crystallographica Section E0.3470.4130.4110.3670.5080.5670.5810.4910.453
Acta Crystallographica Section F1.0721.0560.9681.1990.9890.7990.6470.5240.5680.5520.5060.5630.5510.6060.645
Journal of Applied Crystallography4.8683.3042.9952.8673.4222.6172.5703.9843.9503.3435.1523.7943.0183.2123.6292.4955.2483.5342.3241.8712.5831.752
Journal of Synchrotron Radiation2.5572.6162.2512.4523.2323.0111.8772.7943.0222.1862.7262.3351.9942.3332.9782.382.3921.9191.1440.8851.5190.924

Impact factors are generally calculated based on a three-year period. For example, the 2021 impact factor for a journal would be calculated as follows:

2021 Impact Factor = A/B

where A = number of times articles published in 2019-2020 were cited during 2021 and B = number of articles published in 2019-2020.

Other journal-level statistics

In addition to impact factors, IUCr Journals report a range of journal- and article-level statistics. The journal-level statistics can be viewed by going to the `About' pages of the relevant journal:

Acta Crystallographica Section A: Foundations and Advances
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
Acta Crystallographica Section C: Structural Chemistry
Acta Crystallographica Section D: Structural Biology
Acta Crystallographica Section E: Crystallographic Communications
Acta Crystallographica Section F: Structural Biology Communications
Journal of Applied Crystallography
Journal of Synchrotron Radiation

More information on the statistical indicators that are provided by IUCr Journals is given below.

5-Year impact factor

The 5-year journal impact factor is calculated in a similar fashion to the standard impact factor. Thus, to calculate the 5-year impact factor for 2021, citations are counted in 2021 to the previous five years (2016-2020) and divided by the number of articles published in the previous five years.

Total cites

Total cites provides the total number of times that a journal has been cited by all journals included in the Web of Science database in the reporting year.

Immediacy index

The journal immediacy index indicates how quickly articles in a journal are cited. The immediacy index is calculated by dividing the number of citations to articles published in a given reporting year by the number of articles published in that year.

Cited half-life

This is the median age of the articles that were cited in a given year. Half of a journal's cited articles were published more recently than the cited half-life.

Eigenfactor® score

The Eigenfactor score calculation is based on the number of times articles from the journal published in the previous five years have been cited in the given reporting year, but it also considers which journals have contributed these citations so that highly cited journals will influence the network more than lesser cited journals. References from one article in a journal to another article from the same journal are removed, so that Eigenfactor scores are not influenced by journal self-citation.

Article influence® score

The article influence score determines the average influence of a journal's articles over the first five years after publication. It is calculated by multiplying the Eigenfactor score by 0.01 and dividing by the number of articles in the journal, normalized as a fraction of all articles in all publications.  This measure is roughly analogous to the 5-year journal impact factor in that it is a ratio of a journal's citation influence to the size of the journal's article contribution over a period of five years.

The mean article influence score for each article is 1.00. A score greater than 1.00 indicates that each article in the journal has above-average influence. A score less than 1.00 indicates that each article in the journal has below-average influence.

Journal citation distribution

A journal citation distribution can be generated using the method of Lariviere et al. See for details. The distribution provides an overview of variations in citations received by articles published in the journal.


CiteScore is the number of citations received by a journal in one year to documents published in the three previous years, divided by the number of documents indexed in Scopus published in those same three years.

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