See Issue 755 – Full file size on status bar
You can vote for it there.

Hello,
There is an option to "Show file sizes in bytes" in the Panels in the "Size" column.
But in the status bar, the total size of the selected files is still shown in KB and MB.
For example it shows "438 KB of 13.1 MB in 5 of 57".

How can I configure to show the exact size in bytes, for example "441231 bytes of 12983124 bytes in 5 of 57"?
In case there is no such option, where could I file this as a feature request?

Thanks in advance!

Turn off Show files sizes in short format preference option:
https://winscp.net/eng/docs/ui_pref_panels
You can also toggle is from context menu of Size column title.

Hi Martin,

nowadays (5.x) you show file sizes not in bytes but in rounded values of higher magnitudes.

Could you please introduce a config toggle to re-enable size values in exact bytes instead of
KiB- or MB- or GB-values.

Thanks
Thomas