VoIP Bandwidth Calculator
Work out how much bandwidth simultaneous voice calls need.
Your numbers
Your results
VoIP Bandwidth Calculator by TheCalcTools
How the VoIP Bandwidth Calculator works
Choose the codec, the packet interval and the Layer 2 framing used on the link.
Each voice packet carries payload plus 12 bytes RTP, 8 bytes UDP, 20 bytes IPv4 and the Layer 2 header.
Multiplying the packet size by the packets per second and the number of calls gives the bandwidth.
The formula
Worked example
Using the default values shown in the calculator:
| Codec bitrate | G.711 (64 kbps) |
|---|---|
| Packet interval (ms) | 20 ms |
| Layer 2 overhead (bytes) | Ethernet (18) |
| Simultaneous calls | 50 |
- G.711 at 20 ms packets carries 64 × 20 ÷ 8 = 160 bytes of audio.
- Adding 40 bytes of headers and 18 bytes of Ethernet gives 218 bytes at 50 packets per second.
- That is 87.20 kbps per call each way, or 4.360 Mbps for 50 calls.
Result:
| Payload per packet (bytes) | 160 |
|---|---|
| Packet size (bytes) | 218 |
| Packets per second, each way | 50 |
| Bandwidth per call, one way (kbps) | 87.20 |
| Total bandwidth for all calls, one way (Mbps) | 4.360 |
Frequently asked questions
Why does G.711 need more than 64 kbps?
The codec produces 64 kbps of audio, but every packet adds RTP, UDP, IP and Layer 2 headers. At 20 ms packets that overhead adds roughly 23 kbps.
Does it include call signalling?
No. SIP signalling is small compared with the media, but you should add a margin of 5–10% and use QoS to prioritise voice.
Sources and further reading
Related calculators
More in Cloud & Networking · All calculators
This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.