Direct comparison
PMID vs. DOI: The Difference
PMID is a free PubMed-only citation number from NLM. DOI is a paid, cross-discipline identifier from Crossref/DataCite. Compare scope and authority.
Side-by-side comparison
| Dimension | PMID | DOI |
|---|---|---|
| What it identifies | A citation record indexed in PubMed | A registered digital object — article, dataset, software, etc. |
| Assigning authority | National Library of Medicine (NLM/NCBI) — a single U.S. federal agency | Accredited Registration Agencies (Crossref, DataCite, and others) under the International DOI Foundation |
| Scope / coverage | Biomedical and life-sciences literature indexed in PubMed (MEDLINE journals plus PMC content) | Any content type, any discipline, wherever a registrant pays to register it |
| How it is obtained | Assigned automatically by NLM when a citation is added to PubMed — no request, no fee | Requested and paid for by the publisher, repository, or registrant |
| Format | 1- to 8-digit number, no leading zeros, e.g. 15858184 | Prefix/suffix string, e.g. 10.1038/nature14539 |
| Resolution mechanism | Stable NCBI URL pattern (pubmed.ncbi.nlm.nih.gov/{PMID}) — not a registered resolver protocol | Handle System-based resolver at doi.org, governed under ISO 26324 |
| Governing standard | None — an internal NLM database accession number | ISO 26324 (DOI syntax); DOI Handbook (International DOI Foundation) |
| Cross-discipline use | Biomedical / life-sciences only | Used across all scholarly disciplines |
| Typical citation use | Included alongside a DOI in biomedical (NLM/AMA-style) reference lists | The default persistent identifier for citation managers, ORCID, CRIS systems, and funder reporting |
| Can one work have both? | Yes — most PubMed-indexed articles also carry a DOI | Yes — a DOI-registered biomedical article is usually also PubMed-indexed |
Common questions
FAQ
Does every PubMed article have a DOI?+
Not always — a small number of older or non-standard PubMed citations predate DOI or come from publishers that never registered one, though this is increasingly rare for current biomedical literature.
Does every DOI-registered article have a PMID?+
No — only content NLM indexes into PubMed gets a PMID. Most DOI-registered content — datasets, software, preprints, non-biomedical articles — has no PMID because it falls outside PubMed's biomedical scope.
Is PMID the same as PMCID?+
No. PMID identifies a citation record in PubMed; PMCID identifies a full-text deposit in PubMed Central (PMC). An article can have a PMID without a PMCID, and NIH's Public Access Policy specifically requires citing the PMCID, not the PMID, for compliance.
Which should I cite — PMID or DOI?+
Use the DOI as the primary persistent identifier where available — it is the cross-publisher standard recognized by citation managers, ORCID, and CRIS systems. Include the PMID as a supplementary identifier where a biomedical citation style (e.g. NLM/AMA) calls for it.
