The numbers will never be exact, but with fair certainty, use this.
MP3 Calculations
Formula:
Kbps = bits per second / 8 = Bytes per second x 60 seconds = Bytes per minute x 60 minutes = Bytes per hour
8 Kbps = 8,000 bits per second / 8 = 1,000 Bytes per second x 60 seconds = 60 KB per minute of audio x 60 minutes = 3.6 MB per hour
16 Kbps = 16,000 bits per second / 8 = 2,000 Bytes per second x 60 seconds = 120 KB per minute of audio x 60 minutes = 7.2 MB per hour
32 Kbps = 32,000 bits per second / 8 = 4,000 Bytes per second x 60 seconds = 240 KB per minute of audio x 60 minutes = 14.4 MB per hour
40 Kbps = 40,000 bits per second / 8 = 5,000 Bytes per second x 60 seconds = 300 KB per minute of audio x 60 minutes = 18 MB per hour
48 Kbps = 48,000 bits per second / 8 = 6,000 Bytes per second x 60 seconds = 360 KB per minute of audio x 60 minutes = 21.6 MB per hour
56 Kbps = 56,000 bits per second / 8 = 7,000 Bytes per second x 60 seconds = 420 KB per minute of audio x 60 minutes = 25.2 MB per hour
64 Kbps = 64,000 bits per second / 8 = 8,000 Bytes per second x 60 seconds = 480 KB per minute of audio x 60 minutes = 28.8 MB per hour
80 Kbps = 80,000 bits per second / 8 = 10,000 Bytes per second x 60 seconds = 600 KB per minute of audio x 60 minutes = 36 MB per hour
96 Kbps = 96,000 bits per second / 8 = 12,000 Bytes per second x 60 seconds = 720 KB per minute of audio x 60 minutes = 43.2 MB per hour
112 Kbps = 112,000 bits per second / 8 = 14,000 Bytes per second x 60 seconds = 840 KB per minute of audio x 60 minutes = 50.4 MB per hour
128 Kbps = 128,000 bits per second / 8 = 16,000 Bytes per second x 60 seconds = 960 KB per minute of audio x 60 minutes = 57.6 MB per hour
160 Kbps = 160,000 bits per second / 8 = 20,000 Bytes per second x 60 seconds = 1.20 MB per minute of audio x 60 minutes = 72 MB per hour
192 Kbps = 192,000 bits per second / 8 = 24,000 Bytes per second x 60 seconds = 1.44 MB per minute of audio x 60 minutes = 86.4 MB per hour
224 Kbps = 224,000 bits per second / 8 = 28,000 Bytes per second x 60 seconds = 1.68 MB per minute of audio x 60 minutes = 100.8 MB per hour
256 Kbps = 256,000 bits per second / 8 = 32,000 Bytes per second x 60 seconds = 1.92 MB per minute of audio x 60 minutes = 115.2 MB per hour
320 Kbps = 320,000 bits per second / 8 = 40,000 Bytes per second x 60 seconds = 2.40 MB per minute of audio x 60 minutes = 144 MB per hour
MP3 Calculations
Formula:
Kbps = bits per second / 8 = Bytes per second x 60 seconds = Bytes per minute x 60 minutes = Bytes per hour
8 Kbps = 8,000 bits per second / 8 = 1,000 Bytes per second x 60 seconds = 60 KB per minute of audio x 60 minutes = 3.6 MB per hour
16 Kbps = 16,000 bits per second / 8 = 2,000 Bytes per second x 60 seconds = 120 KB per minute of audio x 60 minutes = 7.2 MB per hour
32 Kbps = 32,000 bits per second / 8 = 4,000 Bytes per second x 60 seconds = 240 KB per minute of audio x 60 minutes = 14.4 MB per hour
40 Kbps = 40,000 bits per second / 8 = 5,000 Bytes per second x 60 seconds = 300 KB per minute of audio x 60 minutes = 18 MB per hour
48 Kbps = 48,000 bits per second / 8 = 6,000 Bytes per second x 60 seconds = 360 KB per minute of audio x 60 minutes = 21.6 MB per hour
56 Kbps = 56,000 bits per second / 8 = 7,000 Bytes per second x 60 seconds = 420 KB per minute of audio x 60 minutes = 25.2 MB per hour
64 Kbps = 64,000 bits per second / 8 = 8,000 Bytes per second x 60 seconds = 480 KB per minute of audio x 60 minutes = 28.8 MB per hour
80 Kbps = 80,000 bits per second / 8 = 10,000 Bytes per second x 60 seconds = 600 KB per minute of audio x 60 minutes = 36 MB per hour
96 Kbps = 96,000 bits per second / 8 = 12,000 Bytes per second x 60 seconds = 720 KB per minute of audio x 60 minutes = 43.2 MB per hour
112 Kbps = 112,000 bits per second / 8 = 14,000 Bytes per second x 60 seconds = 840 KB per minute of audio x 60 minutes = 50.4 MB per hour
128 Kbps = 128,000 bits per second / 8 = 16,000 Bytes per second x 60 seconds = 960 KB per minute of audio x 60 minutes = 57.6 MB per hour
160 Kbps = 160,000 bits per second / 8 = 20,000 Bytes per second x 60 seconds = 1.20 MB per minute of audio x 60 minutes = 72 MB per hour
192 Kbps = 192,000 bits per second / 8 = 24,000 Bytes per second x 60 seconds = 1.44 MB per minute of audio x 60 minutes = 86.4 MB per hour
224 Kbps = 224,000 bits per second / 8 = 28,000 Bytes per second x 60 seconds = 1.68 MB per minute of audio x 60 minutes = 100.8 MB per hour
256 Kbps = 256,000 bits per second / 8 = 32,000 Bytes per second x 60 seconds = 1.92 MB per minute of audio x 60 minutes = 115.2 MB per hour
320 Kbps = 320,000 bits per second / 8 = 40,000 Bytes per second x 60 seconds = 2.40 MB per minute of audio x 60 minutes = 144 MB per hour