Generally if we want to calculate bit rate we use Bitrate=Baudrate*Number of bits per symbol. So for a generate PSK or ASK it'd be Bitrate=Baudrate, for QPSK it'd be Bitrate=2*Baudrate, for 16 QAM it'd be 4*Baudrate. But in OFDM we use multiple modulation schemes like BPSK,QPSK,16QAM and 64 QAM. In such case with what should we multiply the baud rate? What'd be the formula?
If your OFDM system is adaptive, you may have to continuously calculate total bit rate. Just take each subcarrier, and multiply the bit packing per symbol times the symbol rate, and add them all together. If this bit packing changes on a subcarrier, due to noise, for example, you have to recalculate.