Convert AncestryDNA Raw Data to 23andMe Format

You can convert an AncestryDNA raw data file to 23andMe format for free in your browser with the converter at https://healthosx.com/dna/convert/ancestrydna-to-23andme. The tool copies your genotypes into the 23andMe column layout, no-calls stay no-calls, and the file never leaves your device.

How do I convert my AncestryDNA raw data to 23andMe format?

Download your raw DNA file from AncestryDNA, which arrives as a .zip with a .txt inside. Go to the converter page and drop the .zip or the .txt. Choose 23andMe as the output layout and download the converted file. No account, no upload. The conversion runs locally on your device.

What actually changes in the file

A typical AncestryDNA raw file writes each marker as five columns: rsid, chromosome, position, allele1 and allele2. 23andMe writes four columns: rsid, chromosome, position and genotype. The converter joins your two allele columns into one genotype column, so an Ancestry call of A and G becomes AG in the 23andMe file. The position and rsID are copied as they are.

The output first line says the file was converted rather than pretending to be a 23andMe export. That matters because a tool that checks provenance should not be lied to.

The conversion does not change your genotype letters

The converter reads each call and writes the same two letters into the single genotype field. It does not impute missing markers, does not guess genotypes that were not measured, and does not flip the letters to match another strand. A position that failed on the Ancestry chip stays a no-call in the 23andMe file. If you optionally ask it to move GRCh38 positions to GRCh37, letters are flipped only where the chain crosses strands, and positions that cannot be placed are left out and counted.

Your file never leaves your device

The page reads the file in your browser, runs the conversion locally, and builds the download on your device. The site records that a conversion ran and the two formats, never the file, its name or any genotype.

Why do tools ask for 23andMe format when I tested with AncestryDNA?

Some raw DNA tools only take a 23andMe-style text file. They expect rsid, chromosome, position, genotype. AncestryDNA's raw download has five columns, so a parser written for four columns may reject it or read the column names wrong. Converting the layout fixes that without changing the underlying calls.

The limit is marker coverage. The converted file contains the markers AncestryDNA tested, not the ones 23andMe would have tested. If a tool looks for a specific rsID that is not on the Ancestry chip, that marker will simply be absent. The converter does not invent it.

Common mistake: the PDF report or a spreadsheet-saved file

AncestryDNA's PDF report is not raw data. The raw download is the .zip with a .txt inside. Also do not open the raw file in Excel and re-save it before converting. Spreadsheet software can change the separators, quote fields and alter chromosome names. Drop the original .zip or .txt directly.

Where a converted file may still be refused

Usually a converted file works because the columns match. A tool that insists on 23andMe's exact header lines may notice the output says converted and refuse it. That is deliberate. The file is truthful about what it is, and most tools only need the four data columns.

If you want to see your own numbers after the file is in the right layout, run it through the free HealthOS report at https://healthosx.com/dna. It reads the file in your browser the same way and gives you the traits, medication genes and ancestry positions it checks.