Free raw DNA converter
Convert 23andMe raw data to AncestryDNA format
For a tool that wants AncestryDNA’s layout. Drop your 23andMe .txt or .zip and download the same genotypes in five tab-separated columns, with the two letters split and the sex chromosomes and mtDNA numbered the way AncestryDNA numbers them.
It runs in your browser. Your file is never uploaded, there is no account, and it is free. We count that a conversion ran, the two formats and the outcome, never the file, its name or any genotype.
Choose or drop your raw DNA file
.txt · .csv · .zip · .vcf · .vcf.gz · .ped + .map · .bam + .bai
Run the full analysis on this file
The free DNA report reads the same file for ancestry across 15 world regions, traits, medication genes and both family lines. Your DNA story opens straight away with no account; the full report opens after a code sent to your email.
What the converter does
- It reads your file the way the free report at /dna does, so a file /dna reads, this reads: .txt, .csv, .zip, .vcf and .vcf.gz, including the compressed files bcftools and GATK write.
- It writes the same genotypes in the layout you choose: the exact column order, separators, quoting, chromosome names and no-call markers each company’s own download uses. The first line names the layout and says the file was converted, so nobody mistakes it for that company’s export.
- It never changes a genotype. No-calls stay no-calls, and a position that can’t be read is left out and counted.
- GRCh38 positions can be moved to GRCh37 with Ensembl’s map, in your browser. A chip file becomes a GRCh37 VCF with the reference letters from our list of 2.17 million known sites; rows off the list are left out and counted, never guessed.
- A whole-genome BAM (with its .bai index) is read in your browser too: your genotype is called at about two million known positions and written as a VCF or in any chip layout.
Questions
How do I convert 23andMe raw data to AncestryDNA format?
Drop the 23andMe file on healthosx.com/dna/convert/23andme-to-ancestrydna. It splits each genotype into allele1 and allele2, numbers X, Y and MT as 23, 24 and 26, writes a single-letter call (Y and MT, X in men) as two of the same letter, and writes “0 0” for a no-call. It runs in your browser: free, no account, never uploaded.
Can I convert 23andMe raw data to VCF?
Yes, for every position on our list of 2.17 million known sites. Every VCF row names the reference letter at its position, which a chip file doesn’t carry, so the converter takes it from the list (the GRCh37 reference at each site) and leaves out the rows that aren’t on it, rather than guessing. On an AncestryDNA v2 file that is about 95% of the rows. For every row of any chip, bcftools convert --tsv2vcf with a GRCh37 reference genome does the same on your computer.
Can I convert a BAM file to VCF?
Yes, at known positions. Drop the .bam and its .bai on healthosx.com/dna/convert/bam-to-vcf: your browser reads the reads and calls your genotype at about two million known SNPs (every position the consumer chips and the free report read), with the reference letter from the reference genome, and writes a VCF on GRCh37 or GRCh38. It is not a whole-genome variant call: for every rare variant, indels and structural variants, run GATK, DeepVariant or bcftools on the whole BAM. Free, no account, and the BAM is never uploaded.
Can it convert GRCh38 to GRCh37?
Yes, for the chip layouts and PLINK. Positions are moved with Ensembl’s GRCh38-to-GRCh37 map in your browser, the letters are flipped where the map crosses strands, and a position with no single GRCh37 match is left out rather than guessed. A VCF output keeps the build it came in, because a lifted VCF needs the GRCh37 reference letters.
Does converting change my genotypes?
No. The letters are copied as your file has them, and no-calls stay no-calls. Only the layout changes, and the positions if you choose GRCh37.
Is my DNA file uploaded?
No. The file is read and converted in your browser, and the download is made on your device. The GRCh38-to-GRCh37 map is the only thing downloaded, from this site, and only when you choose it.
Why does the FamilyTreeDNA layout have no header?
Because FamilyTreeDNA’s own file has none: its first line is the column names, and tools recognise it that way. The other layouts start with a few comment lines saying the file was converted and which genome build it is on.