The state of California is bigger than the entire country of Italy. How long is your thumb? Who knows! When you don't know the true size of anything, there are sites that will tell you in a jiffy.

All of these web apps don't need you to sign up or download anything to use them. They range in purpose as well. Some let you compare sizes between different objects, others give you a ruler to measure things, and there is even some perspective in the end.

1. iRuler: Get a Ruler on Your Screen to Measure Anything

how to measure compare size of anything

There is no shortage of mobile or desktop apps to turn a screen into a ruler. But the best tool is the oldest one: iRuler. We last reviewed it back in 2009, and it still just works.

The site basically puts a ruler on your screen, adjusting to the screen size and resolution. It tries to auto-detect those two factors, but it never did it right in my tests. You need to select them manually. Once you do, you'll see a perfect ruler on the screen.

iRuler works perfectly on the desktop as well as mobile. And if you tilt the screen, it adjusts the length in portrait or landscape mode. It's a simple app that gets all the little things right. Just make sure you know the screen size and screen resolution.

2. Compare Sizes: Everyday Objects, or Custom Objects, in 3D or 2D

how to measure compare size of anything

This is the site to go to when you want to see a size comparison of objects stacked next to each other without actually finding them in person. Key in the dimensions (weight, height, width) and Compare Sizes will generate a mockup.

The site also comes with several ready templates of everyday objects, like a pack of playing cards or a CD case cover. Add the objects and compare them. You can stack them to see width, check a front view, or even rotate them in a 3D environment.

And finally, go to the item search to look up dimensions of any object online. For example, a quick search for "iPhone" will add those in a couple of clicks. It's an easy and quick way to compare phone or tablet sizes.

3. The True Size: Put One Country Map on Top of Another

how to measure compare size of anything

To really see the size of countries and continents, check out The True Size Of. The site lets you put any country's map on top of any other part of the globe.

Here's how it works. First, type in the name of the country in the top-left box, or that of a US state. You'll get a moveable map that you can drag and drop anywhere you want. You can even make multiples of the same map, to see how many Nevadas make up the whole of America. Each new map comes in a different color too, so you can distinguish them easily.

It's a fun exercise in geography that can give you answers to questions you never thought you had. Here's one for starters: How many USAs do you think we need to cover all the oceans? Try it out, you're in for a shock.

4. MAPfrappe: Draw an Outline, See It Replicated on Another Map

how to measure compare size of anything

MAPfrappe is kind of a customizable version of The True Size that lets you do size comparisons of geographical areas. This time, you get to pick or draw a part of a map. It can be something as large as the whole of the Indian subcontinent, or something as small as the Sunset Strip in LA.

In the left-hand map, draw an outline by clicking points. Then, in the right-hand map, move the map around. The outline's scale and size stay the same. But now you get to pan and zoom to any other part of the world, to see them both next to each other.

True Size is just one of the many ways to compare your country to others, and MAPfrappe lets you handle a lot more than just countries.

5. Reigarw Comparisons: YouTube Channel of Cool Size Comparisons

If you don't want to do the measure or size comparison yourself, let the experts do the heavy lifting. Reigarw is a fascinating YouTube channel that compares one thing to another, and more often than not, it's about sizes.

Apart from this, there are plenty of other cool video comparisons, like hurricane and tornado sizes, famous architecture, aircrafts, and even celebrity height.

Fair warning, this is one of those channels where you'll start watching one five-minute video, and before you know it, an hour has passed!