For debug purposes, replace your sub with: 
sub callback {
    my ( $sftp, $data, $offset, $size ) = @_;
    my $percent = ($offset/$size)*100;
    print "offset=$offset\n";
    print "size=$size\n";
    print "percent=$percent\n";
}

[download]
Then post your results.

In reply to Re: Strange math issue with Net::SFTP by toolic
in thread Strange math issue with Net::SFTP by vendion

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