Measuring correctly
How to test fiber internet speed: a gigabit checklist
To measure a fiber line's real speed, connect your computer to the router with a gigabit-capable Ethernet cable, take Wi-Fi out of the picture and run a multi-connection test while nothing else is using the line. The measured speed is only as fast as the slowest link: on a 1000 Mbps line the best wired reading is about 941.5 Mbps.
- 941.5 Mbps
- Best wired reading on a 1000 Mbps line
- 94.1 Mbps
- Best wired reading on a 100 Mbps line
- 17.6%
- Fixed-line measurements with upload close to download
Checklist before a fiber test
- Connect your computer to the router with an Ethernet cable. On most devices Wi-Fi can't fill a gigabit line.
- Make sure the cable is at least Cat5e; it's printed on it. An old or damaged cable can drop the link to 100 Mbps.
- Check that the router port you use is gigabit. On some routers one of the ports is slower.
- Confirm your network card connects at gigabit: on Windows it's in the network adapter status, on a Mac in Network settings.
- Make sure nothing else at home is downloading, streaming or backing up; even on gigabit these lower the result.
- Keep only the speed test tab open and make sure the device isn't in battery saver.
We explain why these steps matter separately: the effect of Wi-Fi, the limits of your device and the other details of a good test.
The test server must be gigabit too
A speed test can't report more than the server it measures against can deliver. Testing a gigabit line with a single connection or a small server shows the server's limit, not the line's. HIZTESTI uses several parallel connections. Our servers differ in capacity: the measurement server in İzmir has 10 Gbps, the one in Denizli 1 Gbps. When testing a gigabit line, pick İzmir from the server list; a 1 Gbps server hits the same ceiling as your line.
The closer the server, the cleaner the measurement. A distant server doesn't just raise ping; at high speeds it can also slow the transfer down.
On fiber, check upload too
Fiber's clearest difference is upload speed. On copper and cable TV lines upload is a small fraction of download; fiber plans are often symmetric. Only 17.6% of HIZTESTI's fixed-line measurements have upload close to download. If your plan is symmetric but the test shows low upload, it's worth asking your provider. We explain why upload matters in why upload speed matters.
How to judge the result
- If a 1000 Mbps plan measures above 900 Mbps over a cable, your line is running at full capacity.
- If the result gets stuck around 94.1 Mbps, there's a 100 Mbps link in the chain: a port, cable or network card.
- If the wired result is good but Wi-Fi is noticeably lower, that's expected; see the Wi-Fi guide to improve it.
- If wired results drop in the evening, the cause may be congestion rather than the line; see why the internet slows in the evening.
Run a test first to see where your result sits. Start a speed test
The data in detail: charts and diagrams
The gigabit chain: the slowest link sets the result
Distribution of fixed-line download speeds
| Mbps | Share of measurements |
|---|---|
| 0–10 | 14.9% |
| 10–25 | 18.1% |
| 25–35 | 10.2% |
| 35–45 | 8.2% |
| 45–55 | 9.5% |
| 55–75 | 8.2% |
| 75–90 | 6% |
| 90–100 | 6% |
| 100–110 | 2.5% |
| 110–180 | 4.7% |
| 180–200 | 1.8% |
| 200–300 | 3.4% |
| 300–500 | 2.8% |
| 500–900 | 3.1% |
| 900–1000 | 0.7% |
| 1000+ | 0% |
HIZTESTI measurements · 1 Jul – 28 Sep 2026 · fixed line
Frequently asked questions
- Why doesn't my fiber speed test show 1000 Mbps?
- Because of the addressing every packet carries, the best wired reading is about 941.5 Mbps. If you're far below that, the cable, port, network card or Wi-Fi is the slowest link in the chain.
- Can I get gigabit speeds over Wi-Fi?
- On most devices, no. New routers and devices can get close, but distance and walls cut speed quickly. Test over a cable to see your full plan.
- Which cable is good enough for gigabit?
- Cat5e or better (Cat6, Cat6a) is enough for gigabit. The cable type is usually printed on the jacket.
- Is ping lower on fiber?
- Often yes; a fiber access line avoids the error-correction delay copper lines (ADSL/VDSL) add. Distance to the server still decides ping the most.
Sources
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