Fiber Internet Speed: What 1 Gbps and 10 Gbps Plans Really Deliver
Fiber plans are advertised as "up to 1 Gbps" or "up to 10 Gbps". When you actually run a test, though, you may see a few hundred Mbps, or only around 100 Mbps. That does not necessarily mean something is broken.
In this article you will learn why the maximum speed does not show up in tests, how to read your fiber results, the difference between 1G and 10G plans and what 10G needs to pay off, how building wiring and time of day affect speed, and what to keep in mind when looking at fiber speed rankings.
"Up to 1 Gbps" is the technical maximum of the standard
The "up to X Gbps" figure on a fiber plan is the theoretical ceiling of the technology. It is not a promise of the speed you will get. Service offered this way, without a guaranteed speed, is called best effort.
In Japan, for example, NTT East describes the maximum speed of FLET'S Hikari Next as the maximum value under the technical standard, not an indication of actual speeds in use. For FLET'S Hikari Cross (up to roughly 10 Gbps in both directions), it also says the service is best effort and the maximum speed is not always guaranteed. It further explains that because control information is included to maintain communication quality, the actual maximum speed ends up lower by a little over ten percent.
On a 1 Gbps plan, not reaching 1,000 Mbps is perfectly normal.
Why measured speed falls short of the maximum
Your data passes through several segments on its way from the provider's equipment outside your home to your device. If any one segment is narrower than the rest, it sets the limit for the whole path.
| Segment | What happens | How to tell |
|---|---|---|
| Fiber from the local exchange to your home (PON) | A single fiber is split by an optical splitter and shared by several homes in the neighborhood. When usage overlaps, each household's share shrinks | Speed changes a lot depending on the time of day |
| The provider's connection equipment (PPPoE network termination equipment) | With a PPPoE connection, traffic passes through network termination equipment, which tends to get congested when many users are online | Slow only in the evening, and ping gets worse too |
| Wiring inside an apartment building | When the building distributes the connection from a shared room to each unit over phone lines or LAN cables, the in-building limit is lower than with fiber to each unit | Stops at around 100 Mbps even when wired |
| Router and LAN cables | A device with LAN ports limited to 100 Mbps, or a CAT5 cable, can cap your speed | Stops right around 100 Mbps even on a wired test |
| Wi-Fi | Distance, walls, radio congestion and the Wi-Fi generation make it much slower than wired | Fast when wired, slow only on Wi-Fi |
| Device (PC or phone) | CPU performance, the LAN port standard and background updates can set the limit | Only that one device is slow |
PON (passive optical network) splits one fiber among several homes using a splitter. An NTT research and development document, for example, describes a system using a 32-way optical splitter. For step-by-step troubleshooting, see why is my internet slow.
How to read your fiber speed results
This site rates download speed using the bands below (see internet speed guidelines for the full criteria).
| Measured download | Rating | What it means for fiber |
|---|---|---|
| Under 10 Mbps | Insufficient | Low for fiber. Suspect Wi-Fi, your equipment or congestion |
| 10–30 Mbps | Standard | HD video and video calls work, but your fiber may not be performing to its potential |
| 30–100 Mbps | Sufficient | Handles 4K and several devices at once. If it stops around 100 Mbps, suspect a segment with a cap |
| 100 Mbps or more | Fast | A properly fast result for fiber |
Watch out for results that stop at almost exactly 100 Mbps no matter how many times you test. This pattern tends to appear when there is a 100 Mbps limit somewhere in a cable, the router or the building's wiring, rather than in the line itself.
1 Gbps vs 10 Gbps, and what you need to benefit from 10 Gbps
A 10 Gbps plan has a line limit ten times that of a 1 Gbps plan. However, unless every piece of equipment in your home supports 10 Gbps, your limit stays at 1 Gbps or below.
| Equipment | Needed for a 1 Gbps plan | Needed to benefit from 10 Gbps |
|---|---|---|
| LAN cable | CAT5e or better (1 Gbps capable) | CAT6A or better (10 Gbps capable) |
| Router | 1 Gbps LAN ports | 10GBASE-T ports (the 10 Gbps wired LAN standard) |
| PC | 1 Gbps LAN port | A 10 Gbps LAN port or LAN adapter |
| Wi-Fi | Depends on the router and device standards and distance | Using the full 10 Gbps over Wi-Fi alone is difficult. Wired connections are where the speed really pays off |
In Japan, NTT East states that to use FLET'S Hikari Cross at 10 Gbps, you need LAN ports that support 10GBASE-T and LAN cables of Category 6a or higher. Equipment rated from 100 Mbps up to 5 Gbps will still connect, but speed will be limited to that equipment's maximum.
10 Gbps makes sense if you often transfer large files, or if a large household uses the connection on many devices at the same time. If you mainly stream video and browse the web, a 1 Gbps plan that measures 100 Mbps or more is often enough. For Wi-Fi speeds, see why is my Wi-Fi slow.
Why speed differs between houses and apartment buildings
In a detached house, fiber is usually run directly from the utility pole into the home. As long as the equipment inside supports it, this setup tends to deliver speeds close to the plan's maximum.
In an apartment building, fiber is brought to a shared equipment room, and how it is distributed from there to each unit varies from building to building. In Japan, the three methods are:
- Fiber to each unit: fiber reaches every apartment. There is an optical outlet on the wall of the unit.
- VDSL: the connection is carried from the shared room to each unit over existing telephone lines. The outlet in the unit is a phone jack.
- LAN wiring: the connection is carried from the shared room to each unit over LAN cables. The outlet in the unit is a LAN socket.
VDSL and LAN wiring have lower limits than fiber to each unit. The building's management company can tell you for certain which method your building uses.
How plan names relate to building wiring
Many providers sell several fiber plans that look similar but have different maximum speeds. The difference often comes down to the type of home and the wiring method, not just the line itself. A plan for detached houses, a plan for apartments with fiber to each unit, and a plan for apartments using VDSL or LAN wiring may each list a different maximum, and you usually cannot choose one that your building's wiring does not support.
Moving an apartment building from VDSL or LAN wiring to fiber to each unit generally needs the agreement of the building's management and new equipment in the shared room. Depending on the building, it may cost money or may not be possible at all. Before upgrading your plan, check which wiring your building has, since that sets the real ceiling.
Why speed changes with the time of day
A fiber connection shares the fiber from the exchange to your home, the equipment inside your building and the provider's equipment with your neighbors and other residents. In the evening, when usage peaks, one of these can become congested, lowering download speed or raising ping.
Test in the morning, at midday and in the evening under the same conditions. If speed drops sharply only in the evening, congestion is the likely cause. In Japan, if you connect via PPPoE, switching to an IPoE connection may help. For practical steps, see how to increase internet speed.
What to keep in mind with fiber "speed rankings" and "average speed"
The web has plenty of "average speed" figures and "speed rankings" compiled from user test results. They can be useful as a reference, but keep in mind that the numbers are not measured on a level playing field.
- Different user bases: a service with many 10 Gbps subscribers and a service with many customers in VDSL apartment buildings will show different averages, regardless of how good the lines themselves are.
- Different test methods: wired and Wi-Fi results, and PC and phone results, are mixed together.
- Different test servers: the location and number of a test site's servers can change results on the same line.
- Different times of day: the average shifts depending on whether more tests were run in the evening or during the day.
For these reasons, this article does not quote rankings of specific providers. If you want to compare, the most reliable approach is to look at results for your own type of home (house or apartment, and the wiring method) and the times of day you actually use the connection.
How regulators and ISPs report typical speeds
Because advertised maximums say little about everyday performance, regulators and providers in many countries also publish "typical" or "effective" speeds. These figures usually come from repeated tests over a period of time, often taken over a wired connection so that Wi-Fi and home equipment do not skew the results. They are frequently broken down by plan speed, type of home and time of day, including the evening peak.
Such reports are a better guide than the headline number, but they still describe an average across many homes, not your own line. Treat them as a sanity check, and rely on your own wired tests at different times of day to judge what your connection actually delivers.
When you are thinking about switching
If your connection stays slow even after you have checked the equipment in your home, changing your provider or line may be an option. Keep in mind that in an apartment building with VDSL or LAN wiring, changing provider does not change the building's internal limit.
When comparing options, look at the connection technology each one uses to reach your home and how it performs at peak hours, not only the advertised maximum. Before signing up, confirm prices and coverage on each provider's official pages.
Test your own fiber connection
Use this site's speed test to compare a wired PC with Wi-Fi. Testing at different times of day will also show the effect of congestion.
This site has no ads or third-party trackers and runs on the open-source LibreSpeed (LGPLv3). It automatically picks the test server with the lowest ping from our own server in Sapporo and 37 public mirrors around the world (from Honshu, usually "Tokyo").
FAQ
- What is a normal fiber internet speed in Mbps?
On this site's scale, a wired download of 100 Mbps or more is rated "Fast". 30–100 Mbps is rated "Sufficient" and handles 4K video and several devices at once. Testing over Wi-Fi often gives lower results than wired.
- Why do I only get 100 Mbps on a 1 Gbps fiber plan?
Typical causes are a CAT5 LAN cable, a router or PC whose LAN port is limited to 100 Mbps, or VDSL or LAN wiring in an apartment building. In Japan, a government trial found that about 13% of monitors on 1 Gbps plans were capped at 100 Mbps.
- Will a 10 Gbps plan make my internet faster?
Unless your LAN cable (CAT6A or better), router and PC all support 10 Gbps, it will make little difference. If the cause of slow speeds on your current 1 Gbps plan is inside your home, fixing that first is the quicker route.
- Are fiber speed rankings useful?
They can show rough trends, but the users' plans and homes, wired versus Wi-Fi, and the time of testing are not consistent. Looking at results from conditions close to your own home and usage times is more reliable.
- Why is my fiber slow only in the evening?
The fiber, building equipment and provider equipment are shared with your neighbors, so they tend to get congested in the evening when usage peaks. PPPoE connections are said to be prone to congestion at the network termination equipment. Check whether your provider supports IPoE.
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Start the speed testRelated guides
- GuidelinesWhat Is a Good Internet Speed? How to Read Speed Test Results
What download, upload, ping and jitter mean on a speed test, with tables of good internet speeds by activity and connection type, and what to do next.
- Slow connectionWhy Is My Internet So Slow? 10 Causes and How to Narrow Them Down
Ten common reasons your internet or Wi-Fi is slow, and a step-by-step way to find the cause by testing wired, at different times and on other devices.
- Slow connectionHow to Increase Internet Speed: 11 Fixes, Biggest Impact First
11 ways to increase internet and Wi-Fi speed, ordered by impact: which symptom each fixes, cost and time, when 10G helps, and how to check the result.
Sources
- NTT East, "FLET'S Hikari Cross" (Japanese, retrieved 2026-11-12)
- NTT East, "FLET'S Hikari Next" for detached houses (Japanese, retrieved 2026-11-12)
- NTT East, "FLET'S Hikari Next" for apartment buildings (Japanese, retrieved 2026-11-12)
- NTT East, "What is IPoE? Differences from PPPoE, IPv6 and IPv4" (Japanese, retrieved 2026-11-12)
- NTT R&D, "Optical power budget extension technology for long-reach GE-PON systems" (Japanese, retrieved 2026-11-12)
- Sanwa Supply, "How to choose a LAN cable" (Japanese, retrieved 2026-11-12)
- Ministry of Internal Affairs and Communications, Guidelines on Quality Measurement Methods for Fixed Broadband Services (Japanese, September 2024 PDF, retrieved 2026-11-12)