This reverse example treats 32 GB as the nominal decimal capacity 32,000,000,000 bytes. It deliberately does not claim that a formatted card exposes every byte. The arithmetic proves only how many complete stereo 24-bit PCM frames fit inside the supplied capacity.
Start from exact nominal bytes
The decimal unit contract makes 32 GB exactly 32,000,000,000 entered bytes. If the recorder reports a smaller free capacity, enter that value instead. AudioSize floors fractional input bytes before fitting frames so it cannot manufacture a byte that the supplied capacity does not contain.
Fit 5,333,333,333 complete frames
Stereo 24-bit block alignment is 6 bytes. Integer division 32,000,000,000÷6 yields 5,333,333,333 complete frames. Multiplying back uses 31,999,999,998 bytes, proving that the payload stays within capacity and that 2 bytes cannot form another complete stereo frame.
Divide frames by 48,000 Hz
5,333,333,333÷48,000 is the exact rational duration. It displays as approximately 111,111.111104166 seconds, or 30 hours, 51 minutes, and about 51.111104 seconds. The repeating decimal is never turned back into frames, so display rounding cannot increase capacity.
Keep real-world headroom
A recorder may reserve space, create metadata, split files, write multiple tracks, keep pre-roll, or report less free capacity after formatting. Treat the calculated duration as a PCM payload ceiling for the entered bytes, not a promise that a session can safely run until the final frame. Verify media and stop with margin.