Making sure your images load in a reasonable amount of time within your website is important both for your users looking at the website and also for search engine reasons too. When you have the ability to add images to your website yourself, using software like WordPress as I choose to use for my websites, you need to follow best practices to ensure that happens.
Here’s an example….lets imagine you’re a kitchen fitter with a gallery on your website where you want to add some ‘before’ and ‘after’ photos of your recent work. You take some photos on your IPhone at your clients house and have their permission to include these photos of their new kitchen on your website to advertise your work. Your IPhone will take photos of a reasonably high quality say approx 4000 pixels wide as a standard size. Websites can use images at far lower resolutions than those required for print and so something of that size would be significantly more than you would need for the website. If you add your images at that size, say you add 10 new photos to the gallery, then the website needs to process those large images and show them at a reduced size especially when viewing via a mobile phone. This all takes time and will make the page take a while to load up for your users to view. Google will also notice this and as it rewards websites that load quickly, this will not help with your rankings.
What can you do?
So to ensure that your images load quickly on a web page, you need to reduce the size before you upload them into the gallery, page or post. You may be able to do that via your phone or you may have Photoshop or some other software on your computer or Mac that allows you to resize things. As a guide, anything that doesn’t need to stretch full width across a screen would probably do just fine at no more than 1000px in width. So an ‘about’ image on a page, or an image for a blog post such as the one at the top of this page. Larger full width images are usually pretty crisp at around 2000px so the 4000px of the original image is way more than is required.
If you don’t have any software to resize things, there is a great website which allows you to edit images easily called Pixlr https://pixlr.com/e/. Its free, you don’t need to download anything and its got some great features. Upload your photo, edit the size to smaller and then resave. I would always recommend keeping a larger version of your original image safe in case you need to print it as then a larger higher res version would be needed. But having a lower res version for website use is fine and keeps things speedy.
Then you can be sure that using correctly sized images will load up quickly for your users and keep Google and search engines happy too!