VoIP Bandwidth Calculator
Estimate bandwidth per VoIP call by codec and how many concurrent calls your connection can support, free in your browser with this VoIP calculator.
Enter Values
How to use this calculator
- Enter the codec bitrate and number of calls.
- Press Calculate.
How it works
Multiplies the codec bitrate by the simultaneous calls. Real VoIP adds 20–40% for IP/UDP/RTP headers.
Worked example
64 kbps × 10 calls. = 640 kbps (about 0.64 Mbps before overhead).
Common mistakes
- Counting only the codec payload and ignoring IP/UDP/RTP header overhead, which is significant for voice.
- Sizing for average calls when you must provision for the busy-hour peak.
Frequently asked questions
How much bandwidth does a VoIP call need?
It depends on the codec — G.711 uses about 85–100 kbps per call with overhead, G.729 around 30 kbps — multiplied by the concurrent calls.
Why include header overhead?
Voice packets are small and frequent, so IP, UDP and RTP headers can add 30–40% on top of the codec rate; ignoring them under-provisions the link.
Why add overhead to the codec bitrate?
IP/UDP/RTP headers wrap every voice packet, adding roughly 20–40% on top of the raw codec rate. Size the link for the higher figure.
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Cite this tool
Zerdly. (2026). VoIP Bandwidth Calculator. Retrieved from https://www.zerdly.com/tools/voip-bandwidth-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.