Most offices need less bandwidth than they are sold, and more upload than they expect. Add up what happens at the same moment in your busiest hour (HD video calls at roughly 2–4 Mbps each, a VoIP call at about 0.1 Mbps, plus backups and large file transfers), roughly double it for headroom, and buy it symmetrical so upload keeps up. Then make sure you can upgrade quickly rather than buying years of headroom up front.
Bandwidth is the easiest thing to oversell, because more always sounds safer and nobody gets blamed for buying too much. But an oversized circuit is money leaving every month for capacity that never gets used.
Start with concurrent use, not headcount
Twenty staff does not mean twenty simultaneous heavy users. Ordinary office work (email, documents, browsing, most cloud apps) is bursty and light: short spikes, then very little. The load comes from specific activities happening at the same moment, not from the number of desks. So the question is not "how many people?" but "at the busiest moment of a normal week, what is running?"
What common activities use
Approximate figures per user or session. They vary by application and settings, so treat them as planning ranges, not guarantees.
| Activity | Approximate bandwidth | Notes |
|---|---|---|
| Email, browsing, documents, typical SaaS | Light and bursty | Well under 1 Mbps on average per user |
| VoIP phone call | About 0.1 Mbps each way | Needs consistency far more than volume |
| HD video call | About 2–4 Mbps each way | Group calls and screen sharing push toward the top of the range |
| 4K video streaming | About 15–25 Mbps | Download only; relevant for media or training rooms |
| Cloud backup and file sync | Whatever it is allowed | Will fill a circuit if not scheduled or capped |
| Large file transfers | Whatever it is allowed | Sets your ceiling; see the table below |
What speed does to large files
For businesses that move big files (design, video, CAD, imaging, legal discovery), time is the better way to think about bandwidth. Theoretical best case for a 10 GB file, before protocol overhead and the far end's own limits:
| Circuit speed | 10 GB transfer time |
|---|---|
| 100 Mbps | about 13–14 minutes |
| 500 Mbps | about 2.7 minutes |
| 1 Gbps | about 80 seconds |
| 10 Gbps | about 8 seconds |
If your team sends several of those files a day on deadline, the difference between rows is real money. If you send one a week, it is not.
Why upload matters more than the headline number
Consumer-style connections give you a large download and a small upload. The moment you host anything, run VoIP, live on video calls or back up to the cloud, upload becomes your bottleneck. A symmetrical 200 Mbps circuit will often outperform an asymmetric "500 Mbps" one with a small upload for business workloads. When comparing quotes, write down the upload figure for each. It is frequently the number that decides it. Our comparison of DIA, shared fiber and coax explains why the products differ.
A worked sizing example
A hypothetical 30-person office, used to show the method.
| Busiest-hour activity | Estimate |
|---|---|
| 12 video calls at up to 4 Mbps | 48 Mbps |
| 15 VoIP calls at 0.1 Mbps | 1.5 Mbps |
| 30 people on email and SaaS, allow 1 Mbps each | 30 Mbps |
| One 5 GB upload to a client, finished within 10 minutes | about 67 Mbps |
| Total at peak | about 147 Mbps |
Roughly doubling for headroom gives about 300 Mbps, symmetrical. That is a sensible starting point for this office, and a good deal less than the gigabit it might be offered by default. If cloud backups run during the day, schedule them overnight or cap them, or add their rate to the total.
Bandwidth is not the only thing that matters
Latency and jitter
Calls and video depend on delay and its consistency more than on raw capacity. A modest circuit with low, steady latency will sound better than a large one that is congested. Dedicated circuits with an SLA put latency in writing; shared services do not.
Your own network
Many "slow internet" complaints are not the circuit at all. Common culprits: Wi-Fi that is overloaded or poorly placed, an old switch, or a firewall whose real-world throughput with security features turned on is far below its headline number. Before buying a bigger circuit, test speed with a cable plugged directly into the network edge. If that is fast and desks are slow, the fix is inside your office.
Special cases that change the answer
Security cameras
Cloud-connected cameras upload continuously, around the clock. Each HD camera typically sends a few megabits per second, depending on resolution and settings, so a building with twenty cameras can have a steady upload load before anyone arrives. Check your camera system's settings for its actual rate and add it to the total.
Remote staff connecting to the office
If people at home connect by VPN to files or systems in the office, their downloads are your office's uploads. A team working from home can load the office circuit's upload direction more than the same team working at their desks.
Guest Wi-Fi
A waiting room or event space with guest Wi-Fi adds unpredictable demand. Cap it at the firewall so a guest streaming video cannot slow your own calls.
Hosting
If you serve anything to the outside world, from a client portal to a file server, the demand is set by your users rather than your staff, and upload is the number that matters.
Measure before you buy
If you already have a connection, the best sizing data is your own. Ask whoever manages your firewall or router for a month of utilisation data, in both directions, broken down by hour. Look at the busiest hour of the busiest day, not the average. If the peak sits well below your current circuit, a bigger one will not help and the problem may be inside the office. If it sits at the ceiling for long stretches, you have found the bottleneck.
Signs you are under- or over-buying
- Under: calls break up at predictable times of day, uploads crawl while downloads look fine, utilisation graphs sit near the top during working hours.
- Over: utilisation rarely rises above a small fraction of the circuit, even at peak. Ask whoever manages your firewall for a month of usage data; most firewalls record it.
Some carriers also offer burstable billing, where you commit to a base rate and can burst higher, paying for peaks usually measured at the 95th percentile. It suits traffic that is spiky and hard to predict.
Plan for growth without prepaying for it
Bandwidth needs usually grow: more people, more video, more cloud applications, more cameras. That is a reason to buy a circuit that can grow, not one that is already sized for the future. When comparing quotes, look at three things beyond today's price:
- The port size. A 300 Mbps service delivered on a 1 Gbps port can usually be upgraded without new equipment. One delivered on a smaller port may need a site visit.
- Upgrade terms. Whether an upgrade mid-term is allowed, how fast it happens, and whether it restarts your contract.
- The price of the next tier. Ask for it now, so you know what growth will cost.
If you expect a large jump, such as a new team or a move to cloud-hosted video editing, say so at quote stage. It may change which carrier or product is the best fit.
A workable approach
- Add up your realistic simultaneous heavy usage at the busiest hour.
- Add comfortable headroom, roughly double, so peaks do not hurt.
- Confirm the circuit is symmetrical, or that its upload covers your needs.
- Check what an upgrade costs and how quickly it can happen.
That last point matters most. On fiber, moving from 200 Mbps to 500 Mbps is often a configuration change rather than a new install. Buying a right-sized circuit you can grow beats buying three years of headroom up front.
Questions to ask your carrier
- What are the upload and download speeds, separately, and are they guaranteed or "up to"?
- How quickly can I upgrade, and does an upgrade restart my contract term?
- Is there a latency commitment on this circuit?
- Do you offer burstable billing, and how are bursts measured?
- What speed does your equipment hand off to mine, and will my firewall keep up?
- What port size is this delivered on, and what does the next speed tier cost?
Get it sized and priced
Tell us your headcount, what runs on the connection and what frustrates people today, and we will suggest a size and price it across several carriers for your address. If a smaller circuit will do, we will say so. It is free with no obligation, and we usually respond the same day. See Dedicated Internet Access, shared fiber, or voice and UCaaS if phones are part of the picture. Send us the details, or call 478-758-8091 or text (347) 870-0965.
