use warnings;
use strict;
use Tk;
use Tk::Checkbox;

my $mw = MainWindow->new(-title => 'CheckBox size');
my $f = $mw->Frame->pack(-side => 'top');

my $weight1 = "normal";

my $fch = $f->Checkbutton(
     -text     => "Weight",
    -variable => \$weight1,
)->pack(-side => 'left');
my $size = 16;
$fch->configure(-font => [ -size => $size ]);

my $weight2 = "Weight";
my $fch2 = $f->Checkbox(
    -variable   => \$weight2,
    -command    => sub {print "$weight2\n"},
    -onvalue    => "Weight",
    -offvalue   => "Mass",
    -size       => 25,
)->pack(-side => 'left');

MainLoop;