The government says it has hit its target of being able to carry out 500,000 coronavirus tests a day across the UK by the end of October.
The data for 31 October showed just over 525,000 tests could be done – a doubling of capacity in two months.
However, just under 300,000 tests were actually carried out.
Officials said the labs did not work at full capacity as there needed to be flexibility to cope with demand surges or staffing and equipment problems.
The target was set by ministers in early summer as part of the expansion of the Test and Trace system.
By mid-June labs had the capacity to carry out 200,000 tests a day, but during the rest of the summer capacity increased more slowly.
When schools went back after the summer, the labs struggled to cope with demand, leading to the rationing of tests and delays processing tests.
Prime Minister Boris Johnson said it was an important milestone.
"We're now testing more than any other country in Europe."
He said a big push will now be made on getting those who test positive to self-isolate.
"At the moment, alas, the proportion the proportion of people who are self-isolating in response to the urgings of NHS Test and Trace is not yet high enough."
Support payments of £500 have been introduced to encourage those on low incomes to isolate – figures suggest fewer than one in five people complete their self-isolation fully.
How has it been achieved?
The government has used a combination of a network of purpose-built lighthouse labs that are capable of processing tens of thousands of tests a day.
Six of these are now open – with the most recent launched in Newport at the start of October.
The existing labs have also increased capacity in recent weeks by opening extra space and bringing in extra equipment that has meant more of the processing is automated.
Around two-thirds of the capacity is provided in these labs.
Hospitals have also been given resources to carry out extra tests.
Along with universities and private labs, these account for most of the rest of the capacity with more than 100 different labs involved.
There are also contracts with foreign labs to process tests when the need arises – these are thought to amount to no more than 20,000 tests a day.
Why aren't 500,000 tests being processed?
Officials say it is only natural that all the capacity is not being used up.
They say there needs to be flexibility in the system to cope with surges in demand or problems occurring with equipment or staff.
This means labs are expected to work at around 80% of capacity.
Working at or close to capacity means it can take longer for test results to be returned, although latest figures show the system is still struggling to deliver the 24-hour processing the prime minister promised in the summer.
Tests done at regional drive-thru centres, for example, are processed in an average of 39 hours at the moment.