Cách 1
<script type='text/javascript'>
//<![CDATA[
// Change Blogger popular post thumbnail size
// Put this code before </body>.
// See http://bloggersviet.blogspot.com/2015/01/resize-blogger-popular-post-thumbnails.html
$(".PopularPosts img").each(function () { $(this).attr("src", $(this).attr("src").replace(/\/s[0-9]+(\-c)?\//, "/s200-c/")) });
//]]>
</script>
Cách 2
<script type='text/javascript'>
//<![CDATA[
// Change Blogger popular post thumbnail size
// Put this code before </body>.
// By Taufik Nurrohman
function resizeThumb(size){var popularPost=document.getElementById('PopularPosts1');var image=popularPost.getElementsByTagName('img');for(var i=0;i<image.length;i++){image[i].src=image[i].src.replace(/\/s72\-c/g,"\/s"+size+"-c")}}resizeThumb(200);
//]]>
</script>
Cách 3 ( Thay đổi cho cả Youtube Thumbnails)
<script type='text/javascript'>
//<![CDATA[
// Change Blogger popular post thumbnail size
// Put this code before </body>.
// By http://bloggersviet.blogspot.com/2015/01/resize-blogger-popular-post-thumbnails.html
$(document).ready(function(){$('#PopularPosts1 img').attr('src',function(i,src){return src.replace('s72-c','s200-c')})});$(document).ready(function(){$('#PopularPosts1 img').attr('src',function(i,src){return src.replace('default.jpg','mqdefault.jpg')})});
//]]>
</script>
Thay đôi kích thước 200 cho phù hợp với bạn