UK broadband traffic growth has plummeted since lockdown daysUK broadband traffic growth has plummeted since lockdown days

Openreach's latest numbers suggest the UK's data boom is well and truly over. In 2020, when Brits were forbidden from venturing outdoors (even though it was probably the safest place to be), data traffic carried by the country's dominant wholesale provider unsurprisingly exploded, with people forced to choose between talking to relatives and going online. Some 22,000 petabytes had surged through UK broadband infrastructure in 2019. A year later, the annual amount had more than doubled, to about 50,000 petabytes, implying homes quickly ran out of conversation.

But it has taken another four years for the figure to double yet again. It finally surpassed 100,000 in 2024 and reached 103,590 petabytes for the whole year, according to data Openreach – a wholly owned division of BT Group – shared this week. On average, that means data traffic grew by about 13,398 petabytes a year between 2020 and 2024, a huge drop compared with the increase of 28,000 petabytes that occurred in 2020.

Calculating the exact changes that have happened in each of the intervening four years is tricky because of some obfuscation by Openreach. For a start, in its latest statement, it puts last year's increase at 10.5%, implying the petabyte total in 2023 was about 93,747. But the figure Openreach provided last year was actually 94,722. The growth rate based on that is 9.4%, more than a full percentage point lower.

Even more confusing are the figures for 2021 and 2022. In its update two years ago, Openreach said it had carried 64,364 petabytes over its networks in 2022. But this implies a jump of 47%, a network-shaking 30,358 petabytes, a year later. It subsequently transpired that Openreach had oddly neglected to include 22,537 petabytes of full-fiber data in the 2022 amount. Adding that in lowers the growth rate between 2022 and 2023 to just 9%. (This was the only data point Openreach shared regarding the full-fiber correction. Light Reading used to that calculate a revised total of 86,901 petabytes and then deducted 64,364 from this to arrive at a full-fiber amount.)

Funny numbers

The company has not, however, provided any kind of full-fiber correction for 2021, when it originally said that 62,000 petabytes were carried. Again, this implies a massive increase of 40%, or 24,901 petabytes, between 2021 and 2022 before the growth rate plummets to 9% the following year. Openreach previously told Light Reading the full-fiber base was too small before 2021 to make a significant difference to data-traffic statistics.

But it's inconceivable it was too small in 2021, which Openreach finished with about 1.5 million full-fiber connections, compared with roughly 2.7 million a year later. And if the 2021 traffic number ignores full fiber, the total of 62,000 petabytes is probably wrong, as the erratic percentage changes seem to imply. A very crude but generous estimate of the real petabyte total, based on connections that year and the likely appetite of early full-fiber adopters for data usage, produces a growth rate of 49%, an increase of 24,454 petabytes and a much smoother trajectory over the 2020 to 2024 period.

(Source: Openreach data, Light Reading calculations)

As big a surge in a single year as this might sound, it is not as big as the increase that happened in 2020, and the UK was under lockdown not only for several months of 2020 but also for much of 2021. What remains the same in all the various extrapolations is the off-a-cliff drop in last year's annual petabyte increase compared with the figure for 2020, down from 28,000 additional petabytes then to fewer than 8,900 in 2024.

And while that number remains about 1,000 petabytes higher than the increase in 2023, some flattening of traffic levels in future would be no surprise. Increases are likely to have been driven by the UK's recent boom in fiber adoption, which has already happened in other parts of the world. BT's latest numbers show there were 5.5 million Openreach customers on full-fiber connections at the end of September, up from fewer than half a million five years earlier. With the parallel take-up of smart TVs and video-streaming services, many households now watch shows via broadband rather than broadcast technology.

Indeed, Openreach's second-busiest day of 2024 was December 26, when eight Premier League soccer matches were streamed on Amazon Prime. The busiest, though, was December 1. Openreach attributed that to a surge in online shopping for late Black Friday deals as well as a content update for the Fortnite online game.

Whatever lies ahead, BT does not anticipate the need for much additional spending to cope with the volumes of data that Openreach must carry. "Peak capex" was passed in the 2024 fiscal year (ending in March 2024), when BT spent about £5 billion (US$6.2 billion), says Allison Kirkby, BT's CEO, who expects free cash flow to soar from £1.3 billion ($1.6 billion) then to as much as £3 billion ($3.7 billion) in 2030 as she slashes various costs. That would obviously be great for shareholders, but it is not the message employees and Openreach suppliers will want to hear.