It seems like Facebook has a lot of rules – in particular the one stating that some photos can’t be more than 20% text. So it’s a good idea to teach children how to calculate 20% of the area of a photo.

After all, Facebook is here to stay. And it’s likely that your kids will be playing in that sandbox someday (if not already).

First find your dimensions.

Remember the area formula of a rectangle?

A = l x w

All you have to do is plug in your length and width, right?

That may be easier said than done.

These days, we don’t measure pictures in inches. We measure them in pixels.

You can get this information from various sources. But I’m going to use the website WebResizer.

1. Go to their website and click on “Resize Photos Now.”

2. In the “Upload an image” box, click on “Choose File” and select your image.

3. Click on, “upload image” and look at the dimensions underneath the photo.

By the way, Heather at Freebies4Mom.com was the inspiration of this post – and so I’m using one of her images as an example.

Calculate the area – and 20% of it.

Now that you have the length and width, multiply them to get the total area of the image.

In Heather’s image, the area is 300 × 300 = 90,000.

Multiply your area by 0.2. This will give you 20% of the area. This is the legal amount of text you’re allowed to have (for Facebook, these days, anyway).

For us, 90,000 × 0.2 = 18,000.

See how much text you have.

Use the crop function in WebResizer and watch as the crop dimensions change.

In Heather’s Freebies4Mom.com ad, there are three main pieces of text. Here are the screenshots and dimensions of each…

For the main text at the top, the area is 300 × 50 = 15,000:

For the lower left the area is 70 × 50 = 350:

And for the lower right, the area is 80 × 20 = 160:

So our total area is 15,000 + 350 + 160 = 15,510.

Which means Heather should be in the safe zone of 18,000 square pixels.

How much is considered text?

I’m not sure if it’s a human or a computer that measures the area for Facebook approval.

Either way, if you were to use the crop box just slightly larger on the top text, you would immediately hit the 18,000 square pixels limit. Like this:

For this measurement, Heather’s at 300 × 60 = 18,000.

Add to that the 350 square pixels in the bottom left and the 160 square pixels in the bottom right, and she’s in clear Facebook violation.

Math or eyeballing?

So at first this seems like a pretty straightforward exercise.

Heather at Freebies4Mom.com shouldn’t have a problem posting this ad on Facebook. If you do the math, it is within the guidelines of the 20% text rule.

But if the Facebook image auditor measures differently than she does, he will reject this ad. Then the question becomes, “Can she appeal it if it gets rejected?”

Teach it to your kids.

Have your kids visit various Facebook pages and audit them to see if they’re in violation of the 20% text rule.

Oh – and this exercise is in alignment with the Geometry and Ratios & Proportional Relationships domains of the Common Core State Standards!

Heather at Freebies4Mom.com was the inspiration of this post. I used one of her images as the example. She has tons of free stuff everyday, so head over there to get some. Because – after all – free is zero. And zero is math!

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