SIP bandwidth calculator for VoIP calls
Work out how much internet bandwidth you need for your concurrent VoIP calls, by codec and packet size.
Bandwidth per call, each way0
Total for all calls, each way
0Recommended with headroom
0Fax over T.38 uses roughly 15 to 30 kbps per call
How it works
Each packet carries audio plus headers. The calculator multiplies packets per second by packet size, then by your number of calls. Results are estimates, and Opus varies by setting.
Questions
How much bandwidth does one VoIP call use?
With G.711 at 20 ms packets, about 80 kbps each way at the IP level, and about 87 kbps once Ethernet headers are included. G.729 uses far less.
Does bandwidth count both directions?
Yes. A call uses about the same upload and download, so check both.
Why add headroom?
Other traffic and bursts need room. We add 20% by default.
Related: SIP trunking explained.