Bandwidth per User Planner
Size an internet connection on the people using it at once.
What you provide
Offices run 30% to 50%. Hotels and student housing peak far lower than the bed count.
Browsing and email 2 Mbps. Video calls 4 Mbps. HD streaming 8 Mbps. 4K streaming 25 Mbps.
Result
About 130 Mbps at peak, so a 200 Mbps link
Downstream capacity is rarely what people complain about. Upstream is: video calls, cloud backups and file sync all push, and asymmetric connections give the upstream a small fraction of the headline figure. Check the upload rating of any link before signing for it, and check whether the router can actually forward at the rated speed once firewall and inspection features are switched on.
- People served
- 50
- Active at peak40% online at once
- 20
- Per active user
- 5 Mbps
- Peak demand
- 100 Mbps
- With 30% headroom
- 130 Mbps
- Nearest link tier
- 200 Mbps
What this cannot tell you
- A planning estimate from the figures you enter, not a measurement. It does not test your connection or watch your traffic.
- It sizes the link only. Whether the router can forward at that rate with firewall, inspection and VPN features switched on is a separate question, and it is where a surprising number of slow networks actually fail.
Take this with you
How this calculation works
The calculation multiplies your headcount by the share of people genuinely online at the same moment, then by what one active person needs, then adds headroom. That concurrency step is the whole point. Sizing on the full roll is the most common way to buy a connection two or three times larger than the building will ever fill, because a fifty-person office rarely has more than twenty people pulling data at any given second. The result is rounded up to the nearest link tier a provider actually sells.
What the results mean
- Active at peak
- How many people are genuinely moving data at the busiest moment. This is the number the link has to serve, and it is much smaller than the headcount.
- Peak demand
- Active users multiplied by per-user bandwidth. The raw requirement before any safety margin.
- Nearest link tier
- The next connection size upwards that providers actually sell. There is no point specifying 340 Mbps when the choice is between 250 and 500.
Common problems and fixes
- We bought the recommended speed and it still feels slow
- Check upload before anything else. Video calls, cloud file sync and backups all push data, and asymmetric connections give upstream a small fraction of the headline number. A 500/50 line can be saturated upstream by a dozen people on calls while the download graph looks almost idle. After that, look at Wi-Fi, which is usually the real bottleneck between the user and the router.
- Nobody knows what concurrency to use
- Take it from the network rather than guessing. Most routers and access points report connected clients over time, and the peak of that graph on a normal working day divided by the headcount is your figure. Without any data, 40% is reasonable for an office, 20% for a hotel and 60% or higher for a classroom where everyone starts the same task at once.
Frequently asked questions
How much bandwidth does a video call actually need?
Around 2 to 4 Mbps in each direction for a good one-to-one HD call, and roughly the same for a gallery view of a group, since the service composites the streams for you. The figure that matters far more than raw bandwidth is jitter and packet loss. A call on a clean 10 Mbps line beats one on a congested 500 Mbps line every time.
Should I add headroom on top of the peak?
Yes. Traffic is bursty at a timescale no average captures, and a link run at close to capacity develops queueing delay that shows up as lag on calls long before any speed test looks slow. Thirty percent is a reasonable default, more if the growth of the organisation is unpredictable.
Does this apply to a Wi-Fi network too?
The demand side does, but Wi-Fi capacity is not a single number you can divide up. It is shared airtime, so a few devices on a weak, distant signal can consume a disproportionate share and slow everyone. Size the internet link with this, then plan access point coverage separately.
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