Quote from: hosseinimr93 on September 21, 2020, 04:57:14 PM

Quote from: ranochigo on September 21, 2020, 04:25:18 PM

Nope. Each block theoractically can accommodate 1MB of transaction.

If I'm not wrong, theoretically the size of every block can be up to 4 MB.
The block size cannot be bigger than 1 MB if all transactions in the block include only legacy addresses. If Segwit addresses are used, the block size can be bigger than 1 MB.
Please correct me if I am wrong.

Right, 4MB maximum block size is based from the "Weight" so more SegWit transactions will make a block higher than 1MB in disk.
But the maximum block size in virtual Bytes is 1vMB.

To support ranochigo's post: Since we're talking about Electrum's fee estimation, we have to use the "1 (virtual) MB" limit when using "mempool fee estimation".
Because Electrum actually computes the vBytes of its transactions but they are being displayed as Bytes
and the servers which mostly uses Bitcoin core computes its mempool size with vBytes based from this:

Quote from: Bitcoin Core console

getmempoolinfo

Returns details on the active state of the TX memory pool.

Result:
{ (json object)
"loaded" : true|false, (boolean) True if the mempool is fully loaded
"size" : n, (numeric) Current tx count
"bytes" : n, (numeric) Sum of all virtual transaction sizes as defined in BIP 141. Differs from actual serialized size because witness data is discounted