Internet plan speeds are marketed in megabits per second — Mbps — and understanding what those numbers actually translate to for a working office helps you choose the right plan and avoid two common mistakes: overpaying for capacity you'll never use, and underpaying for a connection that genuinely can't keep up with what your team is doing. The speed figures on a plan are just part of the story. Understanding download speed, upload speed, bandwidth, and latency as separate concepts tells you the full picture.
Download speed vs upload speed
Download speed measures how quickly data arrives into your network from the internet. When someone on your team loads a webpage, receives an email attachment, streams a video, or pulls a file from SharePoint, they're downloading. This is the number that NBN providers highlight most prominently — because it's historically been the figure consumers care most about.
Upload speed is the reverse: how fast data leaves your network and goes out to the internet. Every outbound email with an attachment, every file pushed to OneDrive, every video call where your camera is transmitting your image, every VoIP call where your voice is being sent to the other party — that's upload. For a business, upload is happening constantly, and on many connections it deserves more attention than it gets.
Most NBN plans are asymmetric — the download speed is considerably higher than the upload. On a residential-grade NBN 250 plan, the upload speed might be 25 Mbps. On a business-grade plan at the same download tier, the upload ratio is meaningfully better. This is one of the reasons business-grade plans exist and why the price difference is justified for offices where staff are on video calls all day, syncing large files continuously, or using VoIP phones. See Caznet's Business NBN plans for the speed ratios on each tier.
Bandwidth is capacity, not speed
Speed and bandwidth are related but distinct concepts, and the distinction matters for sizing a plan correctly. Speed refers to how fast individual data travels — bandwidth is how much data can flow simultaneously.
A useful analogy: think of your internet connection as a water pipe. Speed is the pressure of the water — how fast it moves. Bandwidth is the diameter of the pipe — how much can flow at once. A 250 Mbps plan doesn't mean every device gets 250 Mbps to itself. It means all your devices share a total capacity of 250 Mbps at any given moment. When one device is downloading a large file at 200 Mbps, the remaining 50 Mbps is shared across everything else on the network.
For a busy office, the question isn't just "is this plan fast?" It's "is this plan wide enough for everyone working at the same time?" A 10-person team doing email and light cloud work might be fine on 100 Mbps. The same plan with 30 staff on video calls, cloud apps, and active file sync might be noticeably constrained.
What your business applications actually need
Breaking the bandwidth question down by application gives you a practical basis for sizing your plan. Some approximate figures for common business workloads:
- A standard-definition video call (Teams, Zoom) uses around 1.5 Mbps upload and download
- A high-definition video call uses 3–4 Mbps each way
- A VoIP phone call uses under 100 Kbps (less than 0.1 Mbps) per concurrent call
- Streaming a YouTube or training video in HD uses approximately 5 Mbps download
- Continuous cloud file sync (OneDrive, SharePoint, Dropbox) varies by file size but easily consumes 10–50 Mbps upload on a busy morning across multiple users
Add up your concurrent users doing concurrent tasks during your busiest period, and you arrive at your actual bandwidth requirement. The speed guide on our NBN page maps common staff counts to recommended speed tiers, which gives a useful starting point. If your workloads are unusually data-intensive for your team size, that guide is a floor rather than a ceiling.
Latency — the other number that matters
Speed test tools report three figures: download speed, upload speed, and latency (ping). Latency is measured in milliseconds and represents how long it takes for a packet of data to travel to a server and back. It's the round-trip time on the network.
For applications like web browsing, email, and file downloads, latency matters relatively little — a few extra milliseconds per request is invisible. For VoIP calls and video conferencing, latency is critical. A latency figure above 50ms on a VoIP call creates perceptible delay and echo. Above 100ms, calls start to feel genuinely awkward.
FTTP connections typically deliver latency below 10ms to the edge of the network. FTTN connections, which rely on a longer copper segment, tend to have higher and more variable latency. This is another dimension where a full-fibre connection outperforms copper-based NBN — and why businesses with VoIP phones should prioritise their connection type, not just their speed tier.
Latency is also affected by your provider's network architecture and how well they manage their backhaul capacity. A plan from a provider with well-managed infrastructure and low contention ratios will deliver better real-world latency than the same headline speed from a provider with a congested network path.
When your internet feels slow but the speed test says otherwise
This is one of the more common frustrations we hear from Adelaide businesses: the speed test shows 300 Mbps, but the internet feels slow. There are several common culprits.
Too many devices sharing available bandwidth is the obvious one — a speed test run on one device doesn't reflect what everyone's connection looks like simultaneously. A cheap consumer router that can't handle the connection state of 30 concurrent devices is another frequent cause — the router is the bottleneck, not the NBN plan. Wi-Fi dead spots and channel congestion create localised speed problems that don't show up when you test from the router room. Background processes consuming bandwidth — software updates, cloud backups running during work hours, antivirus scans — reduce available capacity without being visible. And if your VoIP calls are specifically choppy, SIP ALG on the router is a common culprit — see our SIP ALG article for details.
If you're not sure whether your current plan is right-sized for your team, call us. We'll talk through your staff count, applications, and peak usage patterns and give you a straight answer — without upselling you on speed you genuinely don't need.