who sang how deep is your love

The best‑known version of “How Deep Is Your Love” was sung by the Bee Gees (Barry, Robin, and Maurice Gibb) and released in 1977 for the Saturday Night Fever soundtrack.

Several other songs with the same title exist, so the answer can change depending on which track you mean:

• The 2015 dance track “How Deep Is Your Love” is by Calvin Harris and Disciples, with uncredited vocals by Ina Wroldsen.

• There is also a 2011 song “How Deep Is Your Love?” by the band The Rapture.

If you were thinking of the classic soft‑rock ballad from the 1970s, that one is the Bee Gees version.