Bandwidth Requirement

Free Bandwidth Requirement calculator with clear step-by-step results.

About Bandwidth Requirement

Sizes an internet or WAN circuit from concurrent user count and per-user bitrate. Offered load is grossed up for protocol overhead and retransmissions, then divided by a target utilisation ceiling - running a link above roughly 70% pushes queueing delay and jitter up sharply even though throughput still fits.

Formulas

Offered load

Offered Mbps = users x kbps per user x (1 + overhead) / 1000

Provisioned capacity

Circuit = offered load / target utilisation

Worked example

With the default values below, Bandwidth Requirement returns Circuit size to provision of 492.86. Change any input above and every figure here is recalculated in your browser.

Inputs used

Concurrent usersminimum 1: 200
Sustained bitrate per userminimum 1 kbps: 1,500 kbps
Protocol and retransmit overheadaccepts 0–100 %: 15 %
Target link utilisationaccepts 10–100 %: 70 %

Results

Circuit size to provision: 492.86 Mbps
Offered load at peak: 345.00 Mbps
Provisioned capacity per user: 2,464.29 kbps
Volume if sustained all month: 111.780 TB

Step by step

1Values used
2Offered load
3Provisioned capacity
4Circuit size to provision= 492.86 Mbps
5Offered load at peak= 345.00 Mbps
6Provisioned capacity per user= 2,464.29 kbps
7Volume if sustained all month= 111.780 TB

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

What bitrate should I assume per user?

Roughly 100 kbps for browsing, 1.5 Mbps for 720p video, 3-5 Mbps for 1080p and 25 Mbps for 4K. Voice calls need only 100 kbps but are far more sensitive to jitter.

Why not provision to 100% utilisation?

Packet networks queue. As utilisation approaches capacity, latency and loss rise non-linearly, so interactive traffic degrades long before the link is technically full.