This can be done using Ensembl’s Biomart.
This YouTube video gives a tutorial on how to do it.
The basic steps are:
- Select the Ensembl Variation Database
- Select the Homo sapiens Short Variants (SNPs and indels excluding flagged variants) dataset
- Select the Filters menu from the left hand side
- Expand the General Variant Filters section
- Check the Filter by Variant Name (e.g. rs123, CM000001) [Max 500 advised] box
- Add your list of rs numbers to the box or browse for a file which contains this list
- Click on the Results Button in the headline section
- This should provide you with a table of results which you can also download in Excel or CSV format
If you would like the coordinates on GRCh38, you should use the main Ensembl site, however if you would like the coordinates on GRCh37, you should use the dedicated GRCh37 site.