I remember happening across BioNumbers in one of my classes - I wanted to share it here because it might be useful (and I haven’t seen it posted on the forum yet). I’ve mostly used it for doing rough calculations and/or justifying approximations.
Website: Search BioNumbers - The Database of Useful Biological Numbers
Related article: Milo et al. Nucl. Acids Res. (2010) 38 (suppl 1): D750-D753. https://doi.org/10.1093%2Fnar%2Fgkp889