I am trying to save a wav file as 16 bit PCM but after exporting it reverts back to 32 bit Float. Please help!
It’s probably OK… Audacity works internally at 32-bit float by default and it won’t tell you the bit-depth of the file you just opened.
You can check the file with a tool such as MediaInfo, or as a quick-check right click the file, go to Properties → Details and check the Bit Rate - A “CD quality” 16-bit, 44.1kHz, stereo file will have a bitrate of 1411kbps and will be about 10MB in size for each minute of audio. A 32-bit file will be twice that. A mono file will be half that. A 48kHz file will be a little higher at 1536kbps.
Or, there are 8 bits in a byte, so File size in bytes = Sample Rate (in Hz or samples-per-second) x (bit depth/8) x Number of channels x Playing time in seconds.