Guide
VoIP Bandwidth Calculator
What this VoIP bandwidth calculator does
This calculator estimates the network capacity needed for a group of simultaneous VoIP calls. It is useful when planning a business phone system, checking an office internet connection, or comparing the practical bandwidth impact of different codecs.
How to use the result
Enter the maximum number of calls expected at the busiest time, select the codec used by the phones or provider, and choose a reserve margin. Treat the result as dedicated voice capacity rather than the entire internet plan. Video meetings, cloud applications, backups and normal browsing need additional capacity.
What the estimate includes
The calculation uses concurrent calls, a codec bandwidth estimate and a safety margin. The margin helps account for packet headers and normal variation, but it is not a substitute for measuring traffic generated by the PBX, SBC, phones or softphones.
Important limitations
Actual usage can change with packetisation intervals, RTP overhead, SRTP, VPNs, VLAN tags, silence suppression and provider network design. Download and upload capacity both matter. Quality can also suffer when latency, jitter or packet loss is high even when headline bandwidth appears sufficient.
Frequently asked questions
How much bandwidth does one VoIP call use?
A common planning estimate is about 80 to 100 kbps per call for G.711 or G.722 and about 40 kbps for Opus. Confirm the figure with the provider.
Should I calculate for every extension?
No. Calculate for the number of calls that may occur at the same time, not the number of phones or users. Include expected peak periods and failover traffic where relevant.
What should I do if calls still sound poor?
Check latency, jitter and packet loss with the VoIP call quality scorer, then review queueing, Wi Fi, cabling, firewall rules and the RTP path. See the VoIP troubleshooting guide.