Usually depends on which Satellite products you are using. For instance on Sentinel-2, we do have Level-1C that are Top-of-Atmosphere Reflectances and Level-2A Bottom-of-Atmosphere Reflectances. On both Levels data is coded in a way that the scientific values can be simply obtained as follows:

Reflectance [%] = DN/QUANTIFICATION_VALUE * 100

where QUANTIFICATION_VALUE = 10000

Nasir Hameed Thank you. My KOMPSAT-3 images are Level 1O (ortho-ready) which I'm guessing is in between L1R and L1G. I'm still struggling to figure out what the units are though. When the manual says "radiometrically corrected", what exactly does that mean?

My WorldView images are Level 1B and the product guide says that all images include conversion for absolute radiometry. Does that mean that they have been calibrated to radiance values already or does it simply mean that there are gain and offset values included in the metadata that could be used for a possible calibration?

Sorry if these are stupid questions, but I am relatively new to the field.

Tora Båtvik for WorldView you could also check this product guide: https://dg-cms-uploads-production.s3.amazonaws.com/uploads/document/file/209/ABSRADCAL_FLEET_2016v0_Rel20170606.pdf

Products are already pre-calibrated before the launch but then you need to apply to your images the gains and offsets to get the proper Radiances.

For having the Reflectance instead, there's the dedicated formula too referenced in the document I mentioned.

Cheers.