Why does the fee I set in electrum not match the actual fee?

[markcolls]

I set a fee of 27 sat/byte in electrum, but it came out as 15.5 sat/byte. This happens every time with electrum. How do I correctly set fees in electrum?

[winrate.io]

Do you only have this issue with electrum or does this apply on others as well?

[TryNinja]

Your fee is correct. You chose a fee of 27 sat/vByte, which equals to the 15.5 sat/byte you see. If you use a different block explorer, like Blockstream.info, it will show up in the correct unit, which is the one that matters (sat/vByte).

Take a look at this thread for a better explanation: Fee and Size are different at wallet and explorer

[pooya87]

It is probably because the other place you are checking your transaction on (like a block explorer) is not computing the fees correctly or you aren't paying attention to the unit that was used. There is fee per virtual size (sat/vbyte) value and fee per size (satoshi/byte) value. We have been useing the former to set fees and compare them in bitcoin for the past 3 years.
Can't say more without knowing where you get 15.5 from.

[nc50lc]

I set a fee of 27 sat/byte in electrum, but it came out as 15.5 sat/byte. This happens every time with electrum. How do I correctly set fees in electrum?

Aside from TryNinja's (correct) answer: that will only happen when you're using SegWit.
The reason why those explorers can't compute the same fee as Electrum does is because they're not taking the virtual size in consideration.
And SegWit transaction's "virtual size" is lower than its "size", so the fee per Byte will always be computed lower than fee per virtual Byte when it comes with SegWit.

But when it comes with prioritization, miners will take what you've set in Electrum because it's actually "sat/vByte" although it's displayed as "sat/byte".