Images are incredibly important on any social media profile, whether it’s the ones you use for your profile and cover images, or the ones you share. Last year, more than a third of the links shared on Twitter and more than half of the posts on Facebook News Feed were images.

Images are popular because they are eye-catching and instantly gratifying. However, when uploading images, the content is not the only thing to consider; you also need to think about the file size of the image and its shape.

Here are some ways to optimize the images you display on the top five social networking sites: Facebook, Google+, Twitter, LinkedIn, and Pinterest.

General

Regardless of which site you upload an image to, make sure the file name is relevant to the image. So if the image shows a red dress from your summer collection, call the image red-summer-dress.jpg. Naming your images appropriately will increase the chance that they will show up in the right image searches.

You’ll notice that I named the image file as JPEG. There are a number of image files you can use (JPEG, GIF, or PNG), but using a JPEG is the best option. JPEG files can be greatly compressed, but still have decent quality. Use GIF files for thumbnails and never large images. Use PNG files as an alternative to either of the other two.

Most importantly, make sure all your images are eye-catching and relevant. Post regularly and respond to comments your images receive. Find out which images get the most likes, +1s, and shares and when, then discover the best strategy for leveraging popular images.

Content you post on any social networking site will appear in the feeds of your friends, followers, and connections with a thumbnail version of your profile photo next to it. Make sure that even as a thumbnail, your profile picture is easy to spot.

Keep in mind that social media sites are constantly changing, so while the sizes of the images in this post are accurate (as of 5/29/2013), be sure to check online.

Facebook

Facebook cover photos are the first thing visitors to your Page will see, so make sure they grab their attention. The Facebook cover photo frame is 815px wide by 315px tall. Your profile cover image must clearly relate to your business and must not be misleading or infringe someone else’s copyright. Covers cannot display more than 20% text and cannot contain text that asks users to share the image.

The Facebook profile photo overlaps the cover photo near its bottom right corner. It is 160 x 160 px, but the image you upload to fill the space must be larger than 180 x 180 px. I would advise using your company logo as your profile picture, but try to get creative with your cover photo. If you have time, change it every month or use it to announce new sales or products you have. However, be sure to follow Facebook’s rules.

Timeline images display at up to 403 x 403 px in preview and 960 x 720 px in lightbox. Images up to 2048 x 2048 px can be uploaded. If an image is 403px wide and 603px wide, 200px will be removed from the preview, which would look horrible if those 200px are critical. Don’t expect your page visitors to click through the previews if they can’t see the full image, they will only enlarge the images that intrigue them.

Google+

Google+ cover photos are significantly larger than their Facebook counterparts, measuring 2120 x 1192 px. However, when a user visits your page, they only see the bottom third of the image and have to scroll up to see the rest. You need to make sure that the bottom third of your cover image contains all the necessary details to grab the visitor’s attention.

Current Google+ photos are circular, rather than square, which is great for businesses with circular logos as it reduces negative space, but not so great for those with square logos. If your company has a square logo, find out how best to fit it into the circular frame.

It’s especially important that you optimize SEO for all images on your Google+ page, as well as those you share, because Google indexes everything on your social networking site, making it more likely to show up in Google Search. If a search for your business can lead someone to your Google+ page, it gives them the opportunity to engage and interact with you and the images you post.

Twitter

Unlike Facebook and Google+, Twitter allows you to create and upload a background to your profile page. When you create and upload your background page, make sure all important content is visible by placing it on the left and right edges, so it’s not obscured by your stream, navigation bar, uploaded images, or header image.

Your header image is 520 x 260px, but keep in mind that your 81 x 81px profile image sits pretty much in the middle – you don’t want your profile image blocking out part of your header image, especially if you’ve put your contact details there.

When you post an image to Twitter, there are three different Twitter cards you can use: the Large Image Summary Card features a prominent image, with the corresponding article summary below it; the Photo Card is ideal if you only want to post a photo; use a gallery card for image collections.

In broadcast, a tweet with an image will have a small photo icon at the bottom, with “View Photo” next to it. An image within an expanded tweet is 375 x 375 px, while an article preview image is 120 x 120 px. All the images you tweet can be seen in an image gallery on your profile.

LinkedIn

Your company’s LinkedIn profile page has a series of tabs with customizable banners at the top. The home page banner and the Products and Services banner are 646 x 220 px in size. Treat your homepage banner like Facebook or Google+ cover images: use an eye-catching image that is relevant to your business. Get creative with your Products and Services banner. Why not update it regularly with new products or special offers?

The Careers cover photo is slightly larger at 974 x 238 px, giving you even more room to play. Change the Racing photo from time to time to keep your page fresh. All banners are limited to a maximum size of 2 MB.

interest

Of all the social networking sites on this list, Pinterest is the most image-focused. Pinterest is all about discovering cool and interesting images and pinning them to your own boards. The better the images you pin to your own boards, the more likely people are to follow you.

If you’re a company with tangible products, find interesting ways to post them on your boards. You can even add pricing and availability information to the products you pin on Pinterest using rich pins.

Images you post to Pinterest can be any length, but when previewed they must be 192px wide. When stretched, a pin can still be infinite in length, but is limited to 600px in width. The profile photo frame on Pinterest is 160 x 165 px. It’s also important to choose the right 222 x 150px cover image for each of your boards – it should be the most eye-catching on the board or the one you want the most people to pin.