A mirror journal is a fully open-access (OA) journal that shares the same editorial board, aims and scope, and peer-review standards as an established subscription “parent” journal from the same publisher, but publishes only open-access articles. A mirror journal almost always carries its own ISSN, separate from the parent’s, and is very often named by appending an “X” to the parent title — Elsevier’s Materials Letters: X, a mirror of the subscription title Materials Letters, is one of the most commonly cited examples of the model. Because the mirror and its parent share editors, reviewers, scope, and review criteria, publishers can and do route manuscripts between the two titles, offering authors an immediate open-access outlet without asking the parent journal itself to convert.
Why Publishers Created Mirror Journals
Mirror journals emerged largely as a response to funder open-access mandates — most notably Plan S, the cOAlition S initiative requiring immediate open access to funded research outputs. Plan S explicitly did not accept publication in a hybrid journal (a subscription title that offers an optional pay-to-open-access APC on individual articles) as compliant, except through a time-limited, separately defined “Transformative Journal” status (see below). For a publisher holding a portfolio of prestigious subscription titles — each with an established editorial board, reputation, and submission pipeline — converting the parent outright to full OA risked both subscription revenue and the accumulated brand equity of the title. Launching a mirror journal let the publisher offer a nominally separate, fully open-access outlet under the same editorial umbrella, giving Plan S-funded authors a compliant option without the parent journal itself flipping.
How a Mirror Journal Differs From Other Open-Access Models
The terminology in this space overlaps in ways that trip up even experienced authors. The table below summarizes the structural differences.
| Model | Titles / ISSNs | Reader access | How an author gets OA |
|---|---|---|---|
| Fully OA journal | One title, one ISSN, born OA | Free to all readers by default | All articles are OA; typically one APC track |
| Hybrid journal | One title, one ISSN | Subscription/paywall by default | Author pays an APC to make one article OA inside an otherwise subscription title |
| Mirror journal | Two titles, two ISSNs, one shared editorial board | Parent stays subscription/hybrid; mirror is fully OA | Author submits to (or is routed to) the mirror instead of the parent |
| Transformative Journal (Plan S term) | One title, one ISSN | Subscription/hybrid, with a committed year-on-year rise in OA share | Author pays an APC under a journal formally recognized by cOAlition S as transitioning to full OA |
Note the terminology collision: a Plan S “Transformative Journal” is not the same thing as an institutional transformative agreement (a read-and-publish agreement between a library consortium and a publisher). The two concepts share a name-root but describe different things — one is a status a specific journal title applies for and holds, the other is a licensing deal an institution negotiates covering many journals. cOAlition S stopped accepting new Transformative Journal applications after 30 June 2023 and ended related financial support after 2024, so it is now effectively a closed, legacy pathway rather than an active one for newly launching titles.
Is a Mirror Journal Plan S Compliant? cOAlition S’s Position
This is the most consequential and most contested question for an author choosing between a parent and its mirror. cOAlition S’s own published guidance addresses the arrangement directly:
“Open Access journals must not have a mirror/sister subscription journal with substantial overlap in editorial board to avoid business models charging for both access and publication. Such journals will de facto be considered ‘hybrid’ journals.”
In other words, cOAlition S does not treat a mirror journal as automatically, unconditionally Plan S-compliant simply because it publishes OA content and carries a separate ISSN. Where a mirror shares substantial editorial-board overlap with a subscription parent, cOAlition S reclassifies the arrangement as hybrid for compliance purposes — meaning an article published there may not satisfy a strict Plan S mandate the way publication in a genuinely independent, DOAJ-listed OA journal would.
The dispute over the model predates that formal position. Proponents argue mirror journals are a legitimate, pragmatic transition mechanism: they give authors at well-regarded subscription titles an immediate, recognizable OA route without requiring the parent journal’s whole community, revenue base, and reputation to convert overnight, and they preserve continuity of editorial expertise and peer-review standards that authors and reviewers already trust. Critics — including, notably, a European Commission open-access envoy who publicly warned about the model in 2019 — have characterized mirror journals as a way for publishers to preserve dual revenue (subscription income from the parent plus APC income from the mirror) while offering a nominal OA outlet, without committing the parent title itself to any real transition. cOAlition S’s own de facto hybrid-reclassification guidance reads as a direct response to that second concern. Authors under a Plan S-aligned mandate should not assume a mirror journal is compliant by default; check the specific funder’s or institution’s OA policy and the journal’s own compliance statement before submitting, and treat editorial-board overlap with a subscription parent as the relevant test.
Does a Mirror Journal Inherit the Parent’s Impact Factor?
Generally, no. A Journal Impact Factor is calculated by Clarivate from two years of citation data accrued to a specific, individually indexed journal title. Because a mirror journal is registered as a distinct title with its own ISSN, it does not automatically carry over the parent’s JIF, CiteScore, or indexing status — it must be independently submitted for and accepted into the relevant indexes (Web of Science, Scopus, DOAJ) and build its own citation record before it receives a factor of its own. In practice this typically means a newly launched mirror has no JIF at all for its first several years of operation, even though its parent may be a long-established, highly cited title. For authors in fields or institutions where journal-level metrics weigh into hiring, tenure, or grant assessment, this is a real practical trade-off against the compliance benefit of publishing OA — see our guide on how impact factor and quartile rankings work for how a new title accumulates one.
What This Means for an Author Choosing Where to Submit
- Funder-mandate compliance. Don’t assume a mirror journal satisfies a Plan S-aligned mandate by default — check the funder’s own compliant-journal criteria and, if editorial-board overlap with a subscription parent is substantial, treat it as likely to be classed as hybrid rather than compliant OA.
- Licensing. Plan S requires CC BY by default for funded outputs, with CC BY-SA or CC0 as acceptable alternatives and CC BY-ND permitted only by funder-approved exception. Confirm the specific mirror journal’s default license matches what your funder requires before submitting — don’t assume it matches the parent’s terms.
- APC levels. Mirror journal APCs are set independently of the parent’s subscription price and vary by publisher and title; check the specific journal’s current APC rather than assuming parity with sibling titles in the same portfolio.
- Indexing and prestige signaling. Check whether the specific mirror carries its own JIF/CiteScore and DOAJ listing rather than assuming continuity with the parent’s reputation — this matters most for early-career authors being assessed on journal-level metrics.
- Read-and-publish coverage. Institutional read-and-publish agreements typically name a defined list of eligible hybrid/OA journals; whether a given mirror title is included varies by agreement and publisher, so check your institution’s journal list rather than assume a mirror is automatically covered because its parent is.
Current Trajectory: Are Mirror Journals Being Wound Down?
Mirror journals proliferated in the years following Plan S’s 2018 announcement, with Elsevier’s programme the most extensively documented and studied in the literature. Since then, the model’s strategic value for authors specifically trying to satisfy a strict Plan S mandate has narrowed: cOAlition S’s own guidance treats a mirror with substantial editorial-board overlap as de facto hybrid rather than a straightforward compliance route, which reduces the incentive to use that route purely for mandate purposes (a mirror can still be a reasonable choice for authors under less strict OA requirements, or simply seeking open availability and willing to pay an APC). Individual publishers periodically consolidate underused mirror titles back into their parent or discontinue them, in the way any low-uptake title in a large portfolio might be retired — but this guide does not assert the current live/discontinued status of any specific title, since that status can change without notice. Before submitting, check the specific journal’s own website and its current DOAJ listing rather than relying on any general description of the model.
Publishers That Have Run Mirror-Journal Programmes
Elsevier’s is the most extensively documented and independently studied mirror-journal programme, distinguishing mirror titles from their subscription parents by appending “X” to the name (for example, Materials Letters: X alongside Materials Letters). Other large publishers have explored structurally similar parent-plus-OA-sibling arrangements at various points, but with considerably less independent research coverage available to verify specifics of scope or naming convention — if you are evaluating a mirror journal from a publisher not named here, verify its structure and compliance status directly against the publisher’s own editorial policy page and the journal’s DOAJ record rather than assuming it follows the same pattern as Elsevier’s programme.
Frequently Asked Questions
What is a mirror journal in academic publishing?
A fully open-access journal that shares the same editorial board, scope, and peer-review standards as an established subscription “parent” journal from the same publisher, but publishes only OA content under its own, separate ISSN.
Are mirror journals compliant with Plan S?
Not automatically. cOAlition S’s guidance states that an OA journal with substantial editorial-board overlap with a subscription sibling will de facto be treated as a hybrid journal for compliance purposes, so authors under a Plan S-aligned mandate should check the specific funder’s compliant-journal criteria rather than assume compliance.
Does a mirror journal have the same impact factor as its parent?
No. A mirror journal is a distinct, separately indexed title with its own ISSN, and Journal Impact Factor is calculated per title from that title’s own citation history. A newly launched mirror typically has no JIF until it has been independently indexed and accrued enough citation data of its own.
How is a mirror journal different from a hybrid journal?
A hybrid journal is a single title where readers face a subscription paywall by default and individual authors can pay an APC to make their own article OA. A mirror journal is a separate, fully OA title that sits alongside a subscription parent under the same editorial board — the parent itself may remain subscription-only or hybrid.
How is a mirror journal different from a Plan S Transformative Journal?
A Transformative Journal is a single subscription/hybrid title formally recognized by cOAlition S as being on a committed, reported trajectory to flip entirely to open access. A mirror journal is a second, separate OA title alongside an unconverted subscription parent. cOAlition S closed new Transformative Journal applications after 30 June 2023.
Should I submit to a mirror journal to meet my funder’s open-access mandate?
Check first. Confirm the specific journal’s compliance status against your funder’s own criteria, its default license (CC BY is Plan S’s default requirement), and whether it is independently DOAJ-listed, rather than assuming a mirror journal automatically satisfies an OA mandate because it publishes OA content.
