What is the interval between the cello and the double bass?

The interval between the cello and the double bass is a perfect fifth. The cello is typically tuned to C-G-D-A, while the double bass is tuned to E-A-D-G, which means that the lowest string of the cello (C) is a perfect fifth below the lowest string of the double bass (E). This interval helps to create a rich harmonic foundation in orchestral and chamber music settings.