How to Equalize Your Post Heights
While using 2 or 3 columned layouts for your blog homepage or archive pages, if you have problems about equalizing the heights of your posts, you can set a static size to make their heights equal.
Here's an example of non-equal post heights:
In this example, the post on the left hand side is higher than the other one. So, we should use its height (790px) to equalize the post on the right hand side. To do that, navigate to "Appearance > Customize > 6.3. Post Heights" and write 790 into the "Minimum Height" field:
And here's the result:
Tip 1: Since you're doing this for your whole site, you should find the HIGHEST post and use that post's height.
Tip 2: You can use a browser extension like Page Ruler (for Chrome) to measure the post heights easily.