VoIP bandwidth calculator
Bandwidth needed for a number of simultaneous calls with G.711, G.729 and other codecs.
Runs on your device · nothing is uploaded
Per direction. A call uses the same bandwidth each way, so a full-duplex link needs this amount in both directions.
How VoIP bandwidth is worked out
- The codec sets the voice bit rate (G.711 is 64 kbps, G.729 is 8 kbps).
- Packetisation sets how much audio goes in each packet. At 20 ms there are 50 packets per second each way.
- Every packet carries 40 bytes of IP, UDP and RTP headers, plus the Layer 2 header for the link.
- Bandwidth per call = (payload + headers) × 8 × packets per second.
| Codec, 20 ms | Payload | Per call on Ethernet |
|---|---|---|
| G.711 | 160 bytes | 87.2 kbps |
| G.729 | 20 bytes | 31.2 kbps |
Bandwidth is only half the story: voice also needs low latency (under 150 ms one way), low jitter and almost no loss, so put voice in its own VLAN and give it QoS priority.