Turnitin vs iThenticate: Which Similarity Checker Do Academic Journals Actually Use?

When researchers ask "which similarity checker should I use before submitting to a journal?", the answer depends entirely on where you're submitting. Turnitin and iThenticate are both owned by the same parent company (Turnitin LLC), but they serve different audiences, use different databases, and produce different results for the same manuscript.

The Core Difference: Who Uses Each Tool

The most important distinction is this: iThenticate is the industry standard for academic journal publishers, while Turnitin is primarily used by universities for student submissions.

Publisher-Specific Similarity Thresholds

Different publishers have different acceptable similarity thresholds. Based on publicly available editorial policies and author guidelines as of 2026:

Why iThenticate Scores Are Often Higher Than Turnitin

Researchers frequently report that their iThenticate score is 3–8 percentage points higher than their Turnitin score for the same manuscript. This happens because iThenticate's database includes:

• Published journal articles — Turnitin's database has limited access to paywalled research
• Preprints — bioRxiv, arXiv, SSRN submissions that may include your earlier drafts
• Conference proceedings — especially relevant for Engineering and Computer Science
• Book chapters — particularly relevant for Social Sciences and Humanities

If you posted a preprint of your manuscript on SSRN or ResearchGate before journal submission, iThenticate will match it against your own preprint — potentially adding 10–30% to your similarity score.

What iThenticate Excludes by Default

Most publishers configure iThenticate to exclude certain elements from the similarity calculation. Standard exclusions include:

• Reference lists and bibliographies
• Quoted material (with proper quotation marks)
• Material matching fewer than 8 consecutive words

However, some journals do not exclude references — check the specific journal's author guidelines. If references are included, a paper with 80 citations may have an artificially inflated similarity score simply from shared reference formatting.

How to Check Your Similarity Before Submission

The best pre-submission workflow depends on your budget:

1. Free estimate: Use ScholarAI to identify high-risk passages and get a similarity estimate before spending money on iThenticate
2. Paid iThenticate check: Purchase a single-document check at ithenticate.com (~$5–25) for the exact score your journal will see
3. Institutional access: Many universities provide iThenticate access to researchers — check with your library

Common Sources of High Similarity Scores

In our analysis of manuscripts submitted through ScholarAI, the most common sources of elevated similarity scores are:

• Self-plagiarism (32% of cases): Reusing methodology sections from previous papers without adequate paraphrasing
• Boilerplate academic phrases (28%): Standard phrases like "This study aims to" or "The findings suggest that" appear in thousands of papers
• Literature review overlap (22%): Describing the same foundational studies as many other papers in the field
• Copied preprint (18%): The manuscript matches a preprint version posted by the authors earlier

Turnitin Is Still Relevant: When Academics Need It

Turnitin remains important in two scenarios: when your university requires a Turnitin report as part of thesis submission, and when checking student co-authored papers that may include coursework-derived sections. For final journal submission, however, iThenticate is the authoritative benchmark.

Conclusion

If you're preparing a manuscript for submission to Elsevier, Emerald, Springer, Wiley, or IEEE, iThenticate is the tool your editor will use — not Turnitin. Target below 15% similarity, address preprint self-matches proactively, and use ScholarAI to identify and fix high-risk passages before running your final iThenticate check.