At the moment there are several popular methods for calculating basal exchange, but most of them give extremely average results in the population, or are based on incorrect results, or were created too long ago. For example, the popular Benedict-Harris formula is almost a century old, but many online calculators and mobile applications use it as the backend for calculations.
At HEALBE, we strive to use the latest understanding of human physiology and base our calculations solely on scientific publications from reputable journals, or on our own tests with volunteers.
We now calculate a combination of our observations on users/volunteers and meta-analyses such as https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4535334/