The phrase "actual extent of" is correct and usable in written English.
It can be used when discussing the true or real scope or range of something, often in contexts like research, analysis, or evaluation.
Example: "The actual extent of the damage caused by the storm was much greater than initially reported."
Alternatives: "true scope of" or "real range of".
Yet the actual extent of commercial surveillance on Facebook remains murky.
Consequently, the actual extent of youth violence in London cannot be accurately established.
The actual extent of the "secrecy" of the family courts has been poorly understood.
The ceremony and self-celebration notwithstanding, the actual extent of the blogging community's power is still unclear.
That is why it is so important that five Sunni-dominated states have signed up for the attacks against Isis, whatever the actual extent of their participation.
Official information was being released slowly, leaving the actual extent of the damage unclear after the quake, which had a preliminary magnitude of 6.8.
But the chief inspector warned that the Home Office had not yet established the actual extent of sham marriage immigration abuse in Britain despite recent work to set up a new intelligence system.
But the intelligence community was deeply divided over the actual extent of Iraq's weapons development; the question of Russia's responsibility for cyberattacks in the 2016 election has produced no such tumult.
Though the F.B.I. estimates that the value of this black market is as much as $6 billion a year, we do not really know the actual extent of the trade in illicitly obtained antiquities.
When owners of rights make arrangements for such exploitation by others, the remuneration that they receive in exchange is often in the form of a royalty, usually based on the actual extent of the exploitation.
However, upper bound crack growth properties are required to accurately predict the actual extent of cracking.
