Thank you, and how is this value calculated?
For example, miningpoolstats adds up the hashrate of all the pools in their list and gets the total hashrate. And if the pool is not in the list, then its hashrate is not taken into account.
https://miningpoolstats.stream/bitcoinAs a miner, I was more interested in profit and uninterrupted operation of the equipment than calculation hashrate

But now I want to know a little more.
The client knows the difficulty and it knows how long it takes to find a block over the last 24 hours.
After that math:
Hashrate = ( (blocks solved in last 24 hrs / 144) * difficulty * 2^32 ) / 600
So you get that last rolling 24 hours of hashrate.
Not it's not perfect, but it's close enough.
There could be an unlucky few hours which would cause the hashrate to show lower or a lucky few hours that would show it to be higher.
In the end over the long run you can do the math yourself. You can change the 24 hours to 48 and the 144 to 288 and so on.
-Dave