Last Updated on July 16, 2026 by Dr. Bhagat
Journal Metrics·Updated June 2026
What Is SNIP (Source Normalized Impact per Paper)?
Learn how SNIP corrects for field-specific citation differences so journals across disciplines can be compared fairly.
SectionWhat SNIP is
SNIP was developed by Henk Moed and colleagues at the Centre for Science and Technology Studies (CWTS) at Leiden University in the Netherlands. It was first introduced in 2010 and has since become a standard metric in Scopus, appearing alongside CiteScore and SJR on every journal’s source page. The core problem SNIP solves is simple but profound: different fields cite at different rates.
A paper in molecular biology might easily accumulate 30 citations in three years, while an equally important paper in pure mathematics might receive only 2 or 3. Comparing raw citation metrics across these fields is misleading. SNIP corrects for this by asking not “how many citations did this journal get?” but “how many citations did it get relative to what is normal in its field?” ### The concept of source normalization “Source normalization” is the technique SNIP uses to level the playing field.
Here’s how it works: 1. Calculate the journal’s raw citation impact. Count citations in the current year to documents published in the previous three years, divided by the number of those documents. This gives a raw “citations per paper” figure.
2. Calculate the field’s citation potential. Measure the average number of citations per paper in the journal’s subject field, based on the same Scopus data. This is the “expected” rate.
3. Divide the journal’s impact by the field’s potential. The result is the SNIP score. A score of 1.0 means the journal is exactly average for its field.
A score of 2.0 means it is cited twice as often as expected. This normalization makes SNIP uniquely useful for cross-disciplinary comparisons — a task where raw metrics like the Impact Factor often fail. ### Why SNIP matters for researchers – Fair cross-field comparison. SNIP is the best metric for comparing journals that publish in different disciplines.
– Free and transparent. Like SJR, SNIP is freely available through Scopus and the CWTS Journal Indicators portal. – Corrects for field size. Large fields with many citing papers don’t automatically get higher SNIP scores, because the field’s citation potential is factored out.
SectionHow SNIP is calculated
The SNIP calculation is conceptually straightforward but depends on a robust database (Scopus) to compute the field baselines accurately. ### The SNIP formula SNIP = (Raw citation impact of the journal) ÷ (Citation potential of the journal’s field) Where: – Raw citation impact = Citations in Year Y to documents published in Years (Y-1), (Y-2), and (Y-3) ÷ Number of documents published in Years (Y-1), (Y-2), and (Y-3) – Citation potential = Average number of citations per document in the journal’s subject field, derived from the same 3-year window ### Worked example Suppose Journal A is in molecular biology and Journal B is in mathematics. In 2024: | Metric | Journal A (Molecular Biology) | Journal B (Mathematics) | |——–|——————————|—————————| | Citations in 2024 to 2021–2023 papers | 300 | 30 | | Papers published 2021–2023 | 100 | 20 | | Raw citations per paper | 3.0 | 1.5 | | Field average citations per paper | 2.5 | 0.8 | | SNIP score | 3.0 ÷ 2.5 = 1.20 | 1.5 ÷ 0.8 = 1.88 | Interpretation: Although Journal A has a higher raw citation rate (3.0 vs.
1.5), Journal B has a higher SNIP score (1.88 vs. 1.20) because it performs better relative to its field’s expectations. SNIP reveals that Journal B is actually the more exceptional journal within its discipline.
### Key parameters of SNIP | Parameter | Value | |———–|——-| | Citation window | 3 years (rolling) | | Document types | Articles, reviews, conference papers | | Source database | Scopus (Elsevier) | | Field normalization | Yes (explicit source normalization) | | Prestige weighting | No (all citations equal) | | Self-citation adjustment | Yes (capped if excessive) | | Cost to access | Free |
SectionSNIP vs Impact Factor vs SJR
### Comparison table: SNIP vs Impact Factor vs SJR | Feature | SNIP | Impact Factor | SJR | |———|——|—————|—–| | Developer | CWTS (Leiden University) | Clarivate (Eugene Garfield) | SCImago Research Group | | Source database | Scopus | Web of Science | Scopus | | What it measures | Field-normalized citations per document | Raw citations per citable item | Prestige-weighted citations per document | | Field normalization | Yes — explicit correction | No (JCI is field-normalized) | Yes (inherent via algorithm) | | Prestige weighting | No — all citations equal | No — all citations equal | Yes — prestigious citations count more | | Citation window | 3 years | 2 years (standard) | 3 years | | Self-citation handling | Suppressed if excessive | Suppressed if excessive | Suppressed if excessive | | Cost | Free | Subscription (JCR) | Free | | Best for | Comparing across disciplines | Traditional reputation assessment | Measuring prestige and network influence | ### When to use SNIP over Impact Factor Use SNIP when: – You need to compare journals across different fields (e.g., for interdisciplinary hiring or institutional benchmarking). – You want a metric that corrects for field-specific citation cultures. – You need a free, accessible alternative to the subscription-based Impact Factor.
Use Impact Factor when: – You are evaluating journals within the same discipline. – You need the metric most widely recognized by promotion committees and grant panels. – Your institution’s evaluation criteria explicitly require IF data.
### When to use SNIP over SJR Both SNIP and SJR are free, field-normalized, and based on Scopus data. The difference is philosophical: – SNIP asks: “How does this journal perform relative to its field’s expected citation rate?” – SJR asks: “How prestigious are the journals that cite this journal?” Use SNIP when you care about relative citation efficiency across fields. Use SJR when you care about prestige and network position.
A journal with high SNIP but moderate SJR might be very efficient at attracting citations within its field but not seen as a “destination” journal by elite researchers. Conversely, a journal with high SJR but moderate SNIP might be prestigious but operate in a field with low overall citation rates.
SectionHow to look up SNIP scores
### Method 1: Scopus (Free journal search) 1. Go to www.scopus.com/sources 2. Enter the journal name or ISSN in the search box.
3. Click on the journal title to open its profile. 4.
The SNIP score is displayed alongside CiteScore and SJR. Note: Full Scopus access requires a subscription, but the Sources page is freely accessible for journal metric lookup. ### Method 2: CWTS Journal Indicators (Leiden University) 1. Go to www.journalindicators.com (CWTS Leiden) 2.
Search for the journal by name or ISSN. 3. View the SNIP score, along with the journal’s raw impact and field citation potential.
### Method 3: SCImago Journal & Country Rank Although SCImago primarily displays SJR, it also includes SNIP data for many journals in the detailed journal profile pages. ### Method 4: ImpactFactorForJournal.com journal pages Our journal detail pages display the latest SNIP score alongside the Impact Factor, SJR, CiteScore, and quartile rankings, updated annually from Scopus data.
SectionWhat counts as a good SNIP score
Because SNIP is normalized to a field average of 1.0, interpretation is straightforward: 1.0 is exactly average for the field. Scores above 1.0 indicate above-average performance; scores below 1.0 indicate below-average performance. ### SNIP score benchmarks | SNIP Range | Interpretation | Typical Use | |————|—————|————-| | >2.0 | Exceptional — top 5% of journals in most fields | Flagship journals, Nature/Science tier | | 1.5–2.0 | Very strong — well above field average | Strong target for tenure-track researchers | | 1.2–1.5 | Above average — solid journal | Good target for established researchers | | 1.0–1.2 | Average — performs as expected for the field | Acceptable for most purposes | | 0.8–1.0 | Slightly below average | Verify quality before submitting | | <0.8 | Below average | Consider alternatives unless niche fit is strong | ### Important caveat: SNIP is relative, not absolute A SNIP score of 1.5 means the journal is cited 50% more than expected for its field — but it does not tell you how many citations that is in absolute terms.
A mathematics journal with a SNIP of 1.5 might receive far fewer raw citations than a biology journal with a SNIP of 1.0, because biology has a higher citation baseline. Always pair SNIP with: – Raw citation counts (e.g., CiteScore) to understand absolute impact – SJR to understand prestige and network position – Quartile rankings (Q1–Q4) to see where the journal sits within its field
Key Takeaways
- SNIP corrects for field-specific citation differences.
- A score of 1.0 equals field average.
- Developed by CWTS at Leiden University.
- Use SNIP for cross-disciplinary comparison.
FAQPeople also ask
What is a good SNIP score?
A SNIP score of 1.0 means average performance.
Who developed SNIP?
SNIP was developed by Henk Moed at CWTS, Leiden University.
Can I compare SNIP across disciplines?
Yes. SNIP is specifically designed for cross-field comparison.
Where is SNIP published?
SNIP appears alongside CiteScore and SJR in Scopus.