Sentinel 2 Level 2A units

This is a very basic question but one that I cant seem to find the answer too anywhere. What are the units of the L2A band data? I read that this is meant to be BOA reflectance, but shouldn’t that be a ratio and therefore less than 1? The numbers on the tiles range from low hundreds to low thousands?

In this case you are looking at the raw values stored in the jpeg2000 files. You need to divide these values by the QUANTIFICATION_VALUE (10000). It is given in the metadata. Then you get the reflectance values.
Or simply open the MTD_MSIL1C.xml in SNAP and you will see the correct values automatically

Great thanks! That information did not seem to be easy to come by on the Sentinel website or elsewhere

Sorry where is this QUANTIFICATION_VALUE? In the image folder Or in the metadata opened with Snap?
After atmospheric correction i couldn’t open the metadata file.

it is in the metadata. You can right-click on the metadata in SNAP and search for variable names.
Please see here: Sentinel 2 MSIL1C conversion to Radiance!

Do you get an error message?
Did sen2cor run completely?
Is the image displayed correctly?