Engineering Journal Impact Factor Explained: What It Measures and What It Does Not

The Clarivate Journal Impact Factor is the average number of citations received in one year by the articles a journal published in the two previous years. It describes the journal, not any individual paper, and only journals indexed in Clarivate’s Web of Science receive one. Numbers from other organisations with similar names are not the same metric.

Authors are told to publish in high-impact engineering journals without ever being told what the number counts. It is worth ten minutes, because the misunderstandings around it cost people real decisions.

How it is calculated

The arithmetic is simple. For a 2026 impact factor:

Citations in 2026 to articles published in 2024 and 2025
÷
Number of citable articles published in 2024 and 2025

Two consequences follow immediately, and both are worth holding on to:

• It is an average. A handful of heavily cited papers can lift a journal whose typical article is cited once or twice. The distribution is almost always skewed, and the mean hides that.
• It has a two-year window. That suits fast-moving fields. In engineering sub-fields where useful papers accumulate citations over five or ten years, the window undercounts exactly the work that lasts.

What it describes, and what it does not

The row that matters most is the second. Your paper’s value is its own citations and its own readers. A well-cited paper in a modest journal is worth more to you than an uncited one in a famous journal — and hiring and funding panels increasingly say so.

The metrics that sound like it but are not

This is where authors assessing an engineering journal get misled, and it is deliberate. Several organisations publish numbers with names close enough to be mistaken for the Clarivate figure, sometimes for a fee, with methodologies that are not disclosed.

One test settles it: can you identify who calculated the number, and find the method? The Clarivate figure appears in Journal Citation Reports and can be checked there. A number that appears only on the journal’s own homepage, credited to an organisation you cannot find independently, is marketing.

If a journal quotes an “impact factor” and you cannot find who issued it, treat the number as absent rather than as low.

Other metrics you will meet

They measure different windows and different sources, so they do not agree and are not meant to. Quoting one without naming which is how confusion starts.

Why the same journal scores differently in different lists

Authors sometimes find one engineering journal quoted with three different numbers on three different sites and assume someone is lying. Usually nobody is. The numbers count different things:

• Different windows. Two years for the Clarivate figure, four for CiteScore. A field where papers accumulate citations slowly scores higher on the longer window.
• Different sources. Web of Science and Scopus index overlapping but not identical sets of journals, so the citations each one can see differ.
• Different denominators. What counts as a “citable article” is a definition, and definitions differ. Editorials and letters are treated differently by different systems.

None of this makes the numbers useless. It makes them incomparable across systems, which is a different problem — and it is why any figure quoted without naming the system and the year should be treated as decoration.

How citation habits differ by field

Comparing impact factors across engineering sub-fields is the most common misuse, and it is easy to see why it fails once you look at the mechanics rather than the numbers.

A field with many active researchers, short papers and fast-moving problems generates a lot of citations within two years. A field where the useful output is a small number of long papers, read carefully by a smaller community and cited over a decade, generates very few — and the two-year window closes before most of them arrive.

So a 1.8 in one sub-field can represent a stronger position among its peers than a 4.5 does in another. The only meaningful comparison is between journals a reader would genuinely consider as alternatives for the same paper.

What happens to the number over time

One practical point authors rarely consider: the figure you see today describes citations to papers published two and three years ago. It says nothing about the journal as it is run now.

A journal that changed editors, tightened its review or broadened its scope last year will not show any of that for another two to three years. If you are assessing an engineering journal as it exists today, the review policy, the indexing and the archive tell you more about current practice than a metric describing its past.

Using metrics honestly in your own CV

1. Name the metric and the year. “JIF 2025: 3.2” is checkable; “IF 3.2” is not.
2. Give your own paper’s citations where you have them. That is the number about your work.
3. Do not quote a metric you cannot source. If a panel checks and cannot find it, the damage is to you, not to the journal.
4. Give the DOI. It lets anyone verify the paper in one click, which is worth more than any average.

What to use instead when choosing a journal

For deciding where to send a paper, these affect the outcome far more than any metric:

1. Scope fit. The commonest reason papers are rejected without review.
2. Verifiable indexing. Open each database and search. Our Indexing Information page gives the links so you can check.
3. A described review process. See the publication policy.
4. Registered DOIs. Every article here gets one under the prefix 10.33545.
5. Charges stated before submission, and falling after acceptance.
6. Who actually reads it. For engineering work aimed at practice, open access matters more than any citation average.

Our guide on choosing an engineering journal works through all of these as a one-hour check.

Frequently asked questions

What is a journal impact factor?

The Clarivate Journal Impact Factor is the average number of citations in one year to articles a journal published in the two preceding years. It is calculated by Clarivate and published in Journal Citation Reports; only journals indexed there have one.

Does every engineering journal have an impact factor?

No. Only journals indexed in Clarivate's Web of Science Core Collection receive one. A journal without it is not automatically weak — it simply is not in that index.

What is a good impact factor in engineering?

There is no universal answer, because the number depends heavily on the sub-field. Citation habits differ enormously between, say, biomedical engineering and structural engineering, so comparing across fields is meaningless.

Why do some journals show an impact factor from a body I have never heard of?

Because several organisations sell official-sounding metrics with no relationship to the Clarivate figure. If you cannot identify who calculated a number and how, treat it as marketing rather than a metric.

Should I choose a journal by its impact factor?

It should be one input among several, and rarely the first. Scope, verifiable indexing, a described review process and registered DOIs affect whether your paper is published and found; the impact factor does not.

Is impact factor the same as a citation count for my paper?

No, and this is the most damaging confusion. The impact factor describes the journal, averaged across all its articles. Your paper's own citations are what count for you, and a well-cited paper in a low-scoring journal beats an uncited one in a high-scoring journal.

Related Guides

The metrics this one is most often confused with:

• What is an Indexed Engineering Journal? Databases Explained
• What Makes a Good Engineering Journal? 9 Checks Before You Submit
• How to Choose an Engineering Journal for Your Paper