If you are in X, you can get it from xwininfo. Also if in X, the X11::Protocol module may help.

Here are a couple of other snippets which may( or may not :-) ) work for you :

#!/usr/bin/perl
use Term::ReadKey;
($wchar, $hchar, $wpixels, $hpixels) = GetTerminalSize();

print "$wchar\t$hchar\t$wpixels\t$hpixels\n";
[download]

#!/usr/bin/perl

@x = qx(stty -a);
  @y = split(/;/, $x[0]);

print "screen size is $y[1] $y[2]\n";

########################################### 
#Also, you can specify 'size' to avoid parsing; 
($rows, $cols) = split ' ', qx"stty size </dev/tty 2>/dev/null";

print "screen size is $rows x $cols\n";
[download]