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Calcimator

VoIP Bandwidth Calculator

Bandwidth from concurrent calls, codec, and overhead.

Inputs

%

Results

Required bandwidth (Mbps)

10.46

Raw bandwidth (Mbps)8.72
Bandwidth per call (kbps)174.4
Per call without VAD (kbps)174.4
Payload size (bytes)160
Total packet size (bytes)218
Protocol overhead (%)26.6
Total packets/sec5,000
Estimated MOS (1-5)4.1
Concurrent calls50
How to Use This Calculator
  1. Enter the number of simultaneous VoIP calls.
  2. Select the codec: G.711, G.729, G.722, or Opus.
  3. Set the packet size in milliseconds (20 ms is standard).
  4. Review the Bandwidth Required per Call and the Total Bandwidth for all concurrent calls.
  5. Add 20% overhead for packet headers and network jitter buffer when sizing your internet connection.

How the result changes with Concurrent calls

Concurrent callsRequired bandwidth (Mbps)
1,001209.49
3,501732.69
6,5001,360.32
9,0001,883.52

What each input means

Concurrent calls
Maximum number of simultaneous VoIP calls.
Voice Codec
Select voice codec
Packetization interval (ms)
Audio frame duration per packet. 20ms is standard. Higher = less overhead but more latency.
Voice Activity Detection
Select whether VAD is enabled for bandwidth savings during silence
QoS headroom (%)
Additional bandwidth reserved for QoS marking, jitter buffers, and bursts.
Layer 2 Protocol
Select Layer 2 encapsulation protocol

What each result means

Required bandwidth (Mbps)
Total bandwidth needed including QoS headroom for all concurrent calls (both directions).
Raw bandwidth (Mbps)
Bandwidth without QoS headroom.
Bandwidth per call (kbps)
Effective bandwidth per call (both directions) with VAD if enabled.
Per call without VAD (kbps)
Bandwidth per call without Voice Activity Detection savings.
Payload size (bytes)
Voice payload bytes per packet based on codec and ptime.
Total packet size (bytes)
Complete packet size including all protocol headers.
Protocol overhead (%)
Percentage of each packet consumed by headers vs. voice payload.
Total packets/sec
Aggregate packet rate across all calls (both directions) for network planning.
Estimated MOS (1-5)
Mean Opinion Score estimate for the chosen codec. 4.0+ = toll quality.
Concurrent calls
Number of simultaneous calls sized for.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Concurrent calls = 50, Voice Codec = 0, Packetization interval (ms) = 20, Voice Activity Detection = 0 = 6 input(s) provided
  2. Calculate Required bandwidth
    Required bandwidth = totalBandwidthMbps * (1 + qosHeadroomPct / 100)
    10.46 = 10.46
  3. Calculate Raw bandwidth
    Raw bandwidth = totalBandwidthKbps / 1000
    8.72 = 8.72
  4. Calculate Bandwidth per call
    Bandwidth per call = kbpsPerCall * (1 - vadSavingsPct / 100)
    174.4 = 174.4

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

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