Guide
Contracted vs. real bandwidth: how to measure the gap.
Signing up for '300 Mbps' isn't a promise of exactly 300 Mbps at all times. It's a theoretical maximum capacity subject to network conditions, time of day, and the service contract itself.
What "up to 300 Mbps" actually means
Most residential internet plans are sold with the word "up to" before the number, even though it isn't always emphasized in advertising. That word matters: the advertised figure is the link's maximum capacity under ideal conditions, not a constant guarantee. In practice, factors like congestion on the shared network in your area, distance to the provider's node, the condition of the wiring, and even the time of day can make the real speed fluctuate below that maximum.
Factors that widen the gap between contracted and real
| Factor | Typical impact |
|---|---|
| Shared network congestion (cable, DOCSIS) | Can drop speed 10-30% during peak hours |
| Distance to the exchange (DSL) | Can reduce max available speed by up to 50% |
| Wi-Fi vs. wired Ethernet | 10-70% loss depending on distance, walls and interference |
| Network protocol overhead (TCP/IP) | 3-5% constant loss, even under ideal conditions |
| Remote server capacity | Can cap the final speed even if your connection is fast |
How to reliably measure your real speed
Connect a device directly to the router with an Ethernet cable, close other apps consuming bandwidth (streaming, automatic backups, updates), and use a reliable measurement tool. Repeat the test at least three times throughout the day — early morning, during work hours, and during the evening peak — to get a representative average instead of a single figure that may not reflect your usual experience.
What to do if the gap is too large
Most telecom regulators expect providers to deliver a minimum percentage of the contracted speed, typically between 70% and 80% during peak hours, not 100% at all times. If your consistent measurements show a speed well below that threshold — not a single isolated test, but a repeated pattern over several days — that's when it makes sense to contact your provider with concrete data, instead of a generic "slow internet" complaint.
The difference between plan speed and useful throughput
Even if your provider delivers exactly the contracted speed, that Mbps figure doesn't translate directly into real MB/s of download — you need to divide by 8 and then subtract the typical efficiency for your connection type. You can calculate this concretely with the download time calculator, which already factors in these efficiency rates by connection type.
Verifiable sources
The current broadband definition and regulatory expectations around minimum delivered speed come from the US Federal Communications Commission (FCC), a reference frequently cited across the telecommunications industry in the region.