You've probably noticed that I use some pretty big photos on each blog post here. That should mean big file sizes - but it doesn't have to.
When you take a high resolution digital photo and simply resize it for your web site you are NOT compressing it. Or if you are, then you are probably not compressing it as much as you could be.
Lets take the photo on this post as an example.
The original photo from http://unsplash.com is 720kb and 2511 × 1671 pixels.
I only need an image that is 790 x 420 so I will use Preview on my mac to resize and crop it.
Now the image is only 85kb. That's great but can we do any better?
Yes we can using http://compressor.io. If I upload the resized and cropped image to compressor.io I will now get an even smaller image.
Now the image is only 40.96kb
I have tried many different apps for compressing images. But none of them come anywhere near producing images as small as compressor.io will do. You may be surprised to know that the famous Smush It service from Yahoo only managed to save 1.6kb from the resized 85kb image.
Does it really matter?
Maybe saving 40kb on a single page isn't a big deal. But what if you have more photos on the page? The savings will soon really add up. Remember that the size of the assets on a page is one of the main criteria effecting your page speed and slow pages mean poor google performance.
So yes size does matter!