| Yottaoctets per second (Yo/s) | Gigabits per second (Gbit/s) |
|---|---|
| 1 Yottaoctet per second | 8 × 1015 Gbit/s |
| 2 Yottaoctets per second | 1.6 × 1016 Gbit/s |
| 3 Yottaoctets per second | 2.4 × 1016 Gbit/s |
| 4 Yottaoctets per second | 3.2 × 1016 Gbit/s |
| 5 Yottaoctets per second | 4 × 1016 Gbit/s |
| 10 Yottaoctets per second | 8 × 1016 Gbit/s |
| 20 Yottaoctets per second | 1.6 × 1017 Gbit/s |
| 25 Yottaoctets per second | 2 × 1017 Gbit/s |
| 50 Yottaoctets per second | 4 × 1017 Gbit/s |
| 100 Yottaoctets per second | 8 × 1017 Gbit/s |
| Reference | Yottaoctets per second (Yo/s) | Gigabits per second (Gbit/s) |
|---|---|---|
| A dial-up modem | 7 × 10-21 Yo/s | 0.000056 Gbit/s |
| Typical home broadband | 1.25 × 10-17 Yo/s | 0.1 Gbit/s |
| Gigabit Ethernet | 1.25 × 10-16 Yo/s | 1 Gbit/s |
| Streaming a 4K film | 3.125 × 10-18 Yo/s | 0.025 Gbit/s |
The yottaoctet per second is a unit of data transfer rate equal to a thousand zettaoctets per second, or eight yottabits per second. Its symbol is Yo/s. It is the largest transfer rate the metric system named for thirty years, and it stands at the point where the question stops being one of engineering and becomes one of physics.
The physical limits are real and can be stated. Any communication channel has a capacity set by its bandwidth and its signal-to-noise ratio, a result Claude Shannon proved in 1948. Pushing a rate higher means using more bandwidth, more power, or more parallel channels, and each of those has a cost that grows without limit as the rate does.
Energy sets the sharpest bound. Thermodynamics requires a minimum energy to distinguish one state from another at a given temperature, and although practical systems are many orders of magnitude above that floor, the floor is not zero. At a yottaoctet per second even the theoretical minimum becomes a substantial power, and every real system multiplies it by a large factor.
There is also a limit from the medium itself. A single optical fibre has a capacity ceiling set by non-linear effects in the glass, which grow with the light power carried, so raising the power eventually degrades the signal rather than improving it. Reaching a yottaoctet per second would require something like a hundred billion fibres running at today's records simultaneously, which is a construction problem rather than a communication one.
None of this makes the unit meaningless. It is properly defined, it converts by the same rule as every other, and it appears in discussions of theoretical limits and in complete tables of the prefix system. A measurement system that stopped naming quantities at the point where engineering stops would be less useful, not more.
Since 2022 the metric system has had ronna and quetta above yotta, so this is no longer the top of the ladder. That extension was driven by data quantities rather than by rates, and nothing in transmission has yet given a reason to write a rate above this one.
One yottaoctet per second equals 1,000 zettaoctets per second, 8 yottabits per second, or about 0.8272 yobioctets per second.
The gigabit per second is a unit of data transfer rate equal to one thousand million bits per second. Its symbol is Gbit/s, often written Gbps. It names the standard of wired local networking and, increasingly, of domestic fibre connections.
Gigabit Ethernet was standardised in 1998 for optical fibre and in 1999 for ordinary twisted-pair copper, and the copper version is what made it universal. It runs a hundred metres over the same cabling that carried the hundred-megabit standard before it, which meant buildings could be upgraded by replacing equipment rather than wiring. That single property fixed the gigabit as the default connection for a generation.
In octets a gigabit per second is 125 megaoctets per second. That is roughly the speed of a good mechanical hard drive and well below a modern solid-state drive, which is why gigabit networking is no longer the bottleneck it once was: the network can now outrun the storage at one end or the other in many common setups.
Domestic fibre services advertise a gigabit routinely, and the figure has become a marketing threshold more than a technical one. Practically no household can saturate it — a gigabit is enough for around two hundred simultaneous high-definition video streams — and the benefit in daily use is not throughput but the absence of congestion, which keeps latency low and steady.
Above the gigabit the ladder continues in the same steps. Ten-gigabit Ethernet is standard between servers and switches in data centres; twenty-five, forty, hundred and four-hundred-gigabit links join racks, buildings and cities. Each is a multiple of the same unit, and each is still counted in bits per second because that is what the optics and the copper actually carry.
Wireless has followed. The later wireless local network standards quote peak rates above a gigabit per second, though those figures assume a single device, ideal conditions and the full width of the channel. Real wireless throughput in a normal home is typically a third to a half of the advertised peak, and the gap widens with every additional device.
One gigabit per second equals 1,000,000,000 bits per second, 125 megaoctets per second, or about 0.9313 gibibits per second.