Direct comparison
PMID vs. PMCID: The Difference
PMID is a PubMed citation number; PMCID marks full text in PubMed Central. NIH grant compliance requires the PMCID, not the PMID.
Side-by-side comparison
| Dimension | PMID | PMCID |
|---|---|---|
| What it identifies | A citation record indexed in PubMed | A full-text deposit in PubMed Central (PMC) |
| Assigning authority | National Library of Medicine (NLM/NCBI) — PubMed | National Library of Medicine (NLM/NCBI) — PubMed Central |
| When assigned | Automatically when a citation is indexed in PubMed | Only once the full text is actually deposited into PMC (publisher deposit, NIHMS submission, or another participating route) |
| Format | Plain 1- to 8-digit number, e.g. 15858184 | "PMC" prefix plus digits, e.g. PMC1790863 |
| Does every PubMed article have one? | Yes — virtually all PubMed-indexed articles | No — only articles whose full text has been deposited in PMC |
| NIH Public Access Policy compliance | Not accepted as evidence of compliance | Required identifier for citing NIH-funded publications in progress reports and grant applications |
| Interim identifier | None | NIHMSID (assigned at NIHMS submission), valid as interim compliance evidence for up to 3 months post-publication before a permanent PMCID is expected |
| Where compliance is tracked | Not tracked for compliance purposes | My Bibliography (linked to eRA Commons/SciENcv), which flags applicable publications missing a PMCID |
| Resolution URL | pubmed.ncbi.nlm.nih.gov/{PMID} — citation and abstract | ncbi.nlm.nih.gov/pmc/articles/{PMCID} — full open-access text |
Common questions
FAQ
Can an article have a PMID but no PMCID?+
Yes — this is the normal case, not the exception. Most PubMed-indexed articles are never deposited into PubMed Central unless a funder mandate or publisher OA program requires it, so they carry a PMID but no PMCID.
Which identifier do I cite in an NIH progress report or grant application?+
The PMCID. NIH’s Public Access Policy specifically requires the PMCID (or a valid interim NIHMSID) to demonstrate that a publication was deposited in PMC — a PMID alone does not satisfy the requirement.
What is NIHMSID and can I use it instead of a PMCID?+
NIHMSID is a temporary identifier assigned when a manuscript is submitted through the NIH Manuscript Submission (NIHMS) system, while NLM finalizes the PMC deposit. It can serve as interim compliance evidence for up to three months after publication, after which the permanent PMCID is expected.
How do I check whether my NIH-funded publications are compliant?+
Check My Bibliography, the tool linked to eRA Commons and SciENcv that lists your publications and flags which are subject to the Public Access Policy and whether each has an associated PMCID or valid interim NIHMSID.
Is a PMCID the same as a PMC ID?+
Yes — "PMCID" and "PMC ID" refer to the same identifier; both take the form "PMC" followed by digits, e.g. PMC1790863.
