G.711 Bandwidth Calculator

Calculator Inputs

Codec Variant

Packetization Interval (ms)

IP Version

Layer 2 Encapsulation

MPLS Labels

Concurrent Calls

Traffic Direction

Activity Factor (%)

Safety Margin (%)

Include Ethernet Preamble + IFG

Include VLAN Tag

Include PPPoE Overhead

Include SRTP Auth Overhead

Example Data Table

Scenario	Packetization	IP	Calls	Direction	Typical Use
Branch Voice	20 ms	IPv4	30	Full duplex	Standard enterprise WAN planning
Contact Center	10 ms	IPv4	120	Full duplex	Low-delay voice streams
Secure WAN	20 ms	IPv6	50	Full duplex	SRTP and MPLS environments
Monitoring Link	30 ms	IPv4	12	One-way	Recording or media relay path

Formula Used

1) Payload bytes per packet
Payload Bytes = (Codec Rate in Kbps × Packetization in ms) ÷ 8

2) Total bytes per packet
Total Packet Bytes = Payload + RTP + UDP + IP + Layer 2 + Optional Overheads

3) Packets per second
Packets Per Second = 1000 ÷ Packetization in ms

4) One-way bandwidth per call
One-Way Kbps = (Total Packet Bytes × 8 × Packets Per Second) ÷ 1000

5) Aggregate bandwidth
Aggregate Kbps = Per Call Kbps × Calls × Direction Multiplier

6) Provisioned capacity
Provisioned Kbps = Peak Aggregate Kbps × (1 + Safety Margin)

This model is useful because raw codec rate alone ignores transport, framing, and media-security overhead that often dominates smaller packet sizes.

How to Use This Calculator

Choose the G.711 variant. A-law and mu-law both use 64 Kbps.
Enter the packetization interval, such as 10 ms, 20 ms, or 30 ms.
Select IPv4 or IPv6, then choose the Layer 2 framing.
Enable optional overheads like VLAN, PPPoE, MPLS, SRTP, or Ethernet preamble and IFG.
Enter simultaneous calls and pick one-way or full duplex traffic.
Adjust activity factor if you want a speech-activity estimate.
Add a safety margin for provisioning and future growth.
Click calculate to view totals, the graph, and export options.

Frequently Asked Questions

1. What is G.711 bandwidth?

G.711 bandwidth is the network capacity required to carry a G.711 voice stream, including payload, RTP, UDP, IP, and framing overhead. The true bandwidth is always higher than the 64 Kbps codec rate alone.

2. Why is the real bandwidth higher than 64 Kbps?

Because every voice packet also carries transport and link overhead. RTP, UDP, IP, Ethernet, VLAN, MPLS, and security headers all add bytes. Smaller packetization intervals increase packets per second, which raises overhead further.

3. Does packetization interval matter a lot?

Yes. Shorter intervals reduce voice delay but create more packets every second. That means more header overhead and higher total bandwidth. Longer intervals improve efficiency, but they may increase delay and packet loss impact.

4. Should I calculate one-way or full duplex traffic?

Use one-way when you are sizing a single media path, recording feed, or relay segment. Use full duplex for normal conversations where send and receive streams must both be carried across the same link.

5. What does activity factor mean?

Activity factor estimates how much of the time users are actively sending speech. It can help model average utilization, especially when silence suppression is relevant. Peak planning should still consider worst-case simultaneous activity.

6. Do IPv6 and MPLS change the result noticeably?

Yes. IPv6 adds more header bytes than IPv4, and each MPLS label adds four bytes. On many calls or smaller packet intervals, those extra bytes can materially increase total circuit requirements.

7. Why add a safety margin?

A safety margin protects voice quality during bursts, signaling spikes, routing changes, reporting traffic, and future growth. It also gives engineers room for QoS shaping and operational uncertainty without running links too close to saturation.

8. Is this suitable for WAN and SIP trunk planning?

Yes. This calculator is useful for WAN links, branch circuits, media gateways, SIP trunk sizing, and QoS planning. Always validate with your provider framing, encryption profile, and actual packet captures when possible.