Nucleotide Sequence Download

Download and export nucleotide sequences from NCBI database

Download Format

Sequence Preview

Accession ID Sequence (first 50 bp)

How to use the Nucleotide Sequence Download tool

This tool fetches a contiguous range of NCBI accessions that share the same letter prefix and consecutive numeric suffixes (for example MN223758 through MN223767). Up to 25 sequences may be requested per run. Choose preview length and output format, then download.

  1. Start and end accessions. Enter Start Genbank Accession and End Genbank Accession. The two IDs must use the same prefix (e.g. MN), and the end number must be the start number. The tool expands the range into individual IDs (e.g. MN223758, MN223759, …).
  2. Preview length. Select how many base pairs appear in the Sequence Preview table (50–1000 bp). This affects display only, not the full sequence length in export files.
  3. Download format. Under Download Format, pick one: Single CSV File, Single PDF File, Separate FASTA Files, Separate TXT Files, or Single FASTA File (one combined FASTA with multiple records).
  4. Run the download. Click Download Sequences. The tool retrieves records from NCBI in small batches with pauses to limit rate issues. Watch status messages and the progress bar; the preview table fills as sequences arrive.
  5. Per-request limit. If the range contains more than 25 accessions, the tool stops with a message. Narrow the range or contact the email shown for bulk or commercial use.
  6. Citation. APA, MLA, and BibTeX strings are available under How to Cite below.

Scope: This is range-based retrieval, not a paste-in list of arbitrary unrelated IDs. Use nucleotide accessions for DNA/RNA; protein IDs (e.g. NP_) return protein sequence. Very large individual records may be slow or fail; whole-chromosome scale is better handled outside the browser.

Frequently Asked Questions

What makes a valid start and end accession pair?

Both accessions must share the same leading letter prefix, and the numeric part of the end accession must be greater than or equal to the start. The tool builds every accession in numeric order between those bounds.

Why is there a limit on how many sequences per download?

Each request is capped (typically 25 sequences) to stay within fair use of NCBI services and to keep the browser responsive. For larger batches, split the range into multiple requests or use NCBI’s bulk tools; for commercial-scale needs, use the contact email in the error message.

Which download format should I use?

CSV suits spreadsheets; PDF for a single printable report; single FASTA for one multi-record FASTA file; separate FASTA or separate TXT when you need one file per accession.

Can I paste a list of unrelated accessions?

No. This tool only accepts a single consecutive range with a shared prefix. For unrelated IDs, fetch them individually, use NCBI Batch Entrez, or another pipeline.

Why does my file contain protein sequence?

If you used protein accessions (for example NP_), NCBI returns protein sequence. For DNA or RNA, use nucleotide accessions (for example NM_, NC_, or MN as appropriate).

How to Cite

APA

MLA

BibTeX