This is a VoIP bandwidth calculator. Select your Layer 2 header (Ethernet or MP), your Layer 3 and above header and the voice payload, and it should calculate the required bandwidth.

Layer 2 header

Layer 3 and above header (Note 1)

Voice payload

Payload (bits):

and then to calculate the bandwidth, we need the packets per second (PPS):

PPS

Bandwidth (bps):

Note 1: For IP we get 20 bytes, UDP 8 bytes, RTP 12 bytes. When it is compressed with cRTP we compress this to 2 to 4 bytes.

Theory: [here]