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VoIP Codec Comparison Calculator

Work out voip codec comparison instantly with clear inputs, formula shown and shareable results.

About VoIP Codec Comparison Calculator

A voice call's wire bandwidth is far above its codec rate because each 20 ms packet carries 78 bytes of RTP, UDP, IP and Ethernet headers around a small payload. G.711 at 64 kbps needs about 95 kbps on Ethernet, and G.729 at 8 kbps needs nearly 40 kbps — a five-fold overhead ratio, which is why low-bitrate codecs save less than their headline figure suggests.

Formula

VoIP bandwidth

payload = codec rate x interval / 8; frame = payload + 12 RTP + 8 UDP + 20 IP + 38 Ethernet (+ tunnel bytes); per call = frame x 8 x (1000 / interval)

Worked example

With the default values below, VoIP Codec Comparison Calculator returns Total bandwidth for all calls of 5.712. Change any input above and every figure here is recalculated in your browser.

Inputs used

Codecone of G.711 (64 kbps), G.729 (8 kbps), G.722 wideband (64 kbps), Opus (24 kbps typical)
G.711 (64 kbps)
Packetisation intervalaccepts 5–60 ms
20 ms
Concurrent callsminimum 1
60
Transport overheadone of Ethernet, Ethernet with 802.1Q VLAN tag, IPsec over Ethernet
Ethernet

Results

Total bandwidth for all calls
5.712 Mbps
Bandwidth per call on the wire
95.2 kbps
Packets per second per call
50 pps
Wire rate divided by codec rate
1.49 x

Step by step

  1. 1Values used
  2. 2VoIP bandwidth
  3. 3Total bandwidth for all calls= 5.712 Mbps
  4. 4Bandwidth per call on the wire= 95.2 kbps
  5. 5Packets per second per call= 50 pps
  6. 6Wire rate divided by codec rate= 1.49 x

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Does a longer packetisation interval save bandwidth?

Yes, substantially, because header overhead is amortised over more payload. The cost is added latency and losing more audio when a packet is lost.

Why is G.729 less of a saving than expected?

Headers dominate. Going from 64 to 8 kbps codec rate only takes wire bandwidth from about 95 to 40 kbps, not to 12.

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