| Exabits per second (Ebit/s) | Petabits per second (Pbit/s) |
|---|---|
| 1 Exabit per second | 1000 Pbit/s |
| 2 Exabits per second | 2000 Pbit/s |
| 3 Exabits per second | 3000 Pbit/s |
| 4 Exabits per second | 4000 Pbit/s |
| 5 Exabits per second | 5000 Pbit/s |
| 10 Exabits per second | 10000 Pbit/s |
| 20 Exabits per second | 20000 Pbit/s |
| 25 Exabits per second | 25000 Pbit/s |
| 50 Exabits per second | 50000 Pbit/s |
| 100 Exabits per second | 100000 Pbit/s |
| Reference | Exabits per second (Ebit/s) | Petabits per second (Pbit/s) |
|---|---|---|
| A dial-up modem | 5.6 × 10-14 Ebit/s | 5.6 × 10-11 Pbit/s |
| Typical home broadband | 1 × 10-10 Ebit/s | 0.0000001 Pbit/s |
| Gigabit Ethernet | 0.000000001 Ebit/s | 0.000001 Pbit/s |
| Streaming a 4K film | 2.5 × 10-11 Ebit/s | 0.000000025 Pbit/s |
The exabit per second is a unit of data transfer rate equal to a thousand petabits per second. Its symbol is Ebit/s. No link, no cable and no exchange point runs at this rate; the unit describes the internet as a whole, or a large part of it, at a single instant.
Global internet traffic can be expressed this way. Worldwide traffic of several hundred exaoctets a month works out to roughly one exabit per second on average, and peak hours run higher. That figure is the sum of every packet moving on every network on the planet, and it is the only quantity anyone routinely describes at this scale.
An exabit per second is 125 petaoctets per second. Nothing generates data at that rate in one place; the number is an aggregate of billions of separate flows, most of them tiny. A single video stream is a few megabits per second, so an exabit per second is on the order of a hundred million such streams running at once.
The composition of that traffic is dominated by video. Streaming services account for the largest share, followed by social platforms, software updates and cloud synchronisation. Ordinary web browsing and messaging, which people think of as the internet, are a small fraction of the total by volume even though they occupy most of the attention.
The unit also appears in projections of aggregate capacity. The total installed capacity of all submarine cables, if every wavelength on every fibre pair were lit and used simultaneously, is in the exabit-per-second range. Actual utilisation is far below that, because capacity is built ahead of demand and because routes must carry each other's traffic when a cable fails.
The prefix exa is a thousand to the sixth power. It was adopted in 1975, when nobody expected it to describe anything but astronomical quantities, and it now describes the working throughput of a communications system built by human beings. The interval between definition and everyday use was about forty years.
One exabit per second equals 1,000 petabits per second, 125 petaoctets per second, or about 0.8674 exbibits per second.
The petabit per second is a unit of data transfer rate equal to a thousand terabits per second. Its symbol is Pbit/s. It marks the frontier of optical transmission research: the rate at which laboratories have carried data down a single strand of glass, and which no deployed system yet approaches.
The records were set by combining three techniques. Multi-core fibre puts several separate light-guiding paths inside one cladding, so that a single strand behaves like a bundle. Wavelength division multiplexing runs hundreds of distinct colours down each of those cores. Advanced modulation encodes many bits into each pulse. Multiplying the three together is what reaches a petabit per second.
Such demonstrations run over tens of kilometres of fibre in controlled conditions, not the thousands of kilometres a working sea cable must span. Distance is the hard part: signals attenuate, dispersion smears pulses together, and non-linear effects in the glass grow with power. Every kilometre added makes the same rate harder to sustain, which is why deployed cables sit two orders of magnitude below the laboratory record.
In octets a petabit per second is 125 teraoctets per second, which is roughly the storage of a hundred and twenty-five large hard drives moved every second. Nothing at either end of such a link could produce or absorb data at that rate; the figure describes the medium's capacity rather than any use of it.
At the network level the unit is used for aggregates. The total interconnect capacity of a very large data centre, the summed capacity of all the cables landing on a continent, and the peak traffic of the largest content networks are quoted in petabits per second. These are sums over thousands of links, not the rating of any one.
The trajectory is worth noting. Transoceanic capacity has grown by roughly a factor of ten every seven or eight years for several decades, driven almost entirely by better electronics and better coding rather than by more glass. If that continues, the petabit per second will describe a working cable within a generation.
One petabit per second equals 1,000 terabits per second, 125 teraoctets per second, or about 0.8882 pebibits per second.