What internet speed does my business actually need?
A simple way to size bandwidth by headcount and workload - and why upload speed and contention matter more than the headline number.
By the Telappliant team
Bandwidth is easy to overbuy and easy to underbuy, and the headline download figure is the least useful number in the quote. Here is a straightforward way to size a business connection without guessing.
The three numbers that matter
- Download: how quickly your users pull data down, which is the number providers advertise
- Upload: how quickly you push data up, which decides call quality, cloud backup windows, file sharing and remote desktop
- Contention: how many other customers share the same capacity, which is why an 80Mbps line can feel slow at 4pm
A quick sizing method
Start with a working allowance of 3 to 5Mbps per concurrent user for ordinary cloud work: email, Microsoft 365, browsing and a video call. Add 100 to 150Kbps per concurrent voice call. Then add headroom for the scheduled jobs nobody counts: cloud backup, endpoint patching, image deployment and CCTV upload. Finally, double the upload allowance if you run remote desktops, transfer large media or design files, or back up to the cloud during the day.
Worked examples
- 8 people, cloud email and calls, no heavy files: 100 to 300Mbps FTTP is comfortable
- 25 people, Microsoft 365, VoIP and cloud backup: 500Mbps to 1Gbps FTTP, or a 100 to 200Mbps leased line if uptime matters
- 60 people, remote desktops, CAD or media, multi-site: a symmetrical leased line from 200Mbps upwards, with failover
- Any site where an outage stops trading: a dedicated line with an SLA, plus a diverse backup circuit
Why symmetry matters more than the headline speed
Consumer and FTTC-style products are asymmetric: a large download figure with a small upload. Every modern workload is bidirectional. A 900/110 line and a 500/500 line look very different on paper, and the 500/500 line will feel faster for calls, backup and remote access.
Do not buy speed to fix a reliability problem
If calls break up or the cloud stalls intermittently, more bandwidth usually changes nothing. The cause is normally jitter, packet loss, a saturated upload, an overworked router or a missing quality-of-service policy. Measure before you upgrade: a week of monitoring costs nothing and often saves a contract.
What to check before signing
- The committed rate, not the up-to figure
- The contention ratio, or whether the bandwidth is dedicated
- The service level: target fix time, service credits and out-of-hours cover
- Whether the price includes the router, installation and any excess construction charges
- Contract length and what an in-life upgrade costs
Next steps
Frequently asked questions
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