This is a debatable topic. There’s no exact guide for us to follow. But, the rule of thumb is that each photo should be lesser than 100Kb.
Google says that high page loading time decreases sales. Sites loading between 1 to 3 secs have 32% higher bounce rate than the sites which load under 1 minute.
Shoppers are really having no time nowadays.
Do you see the increase in bounce rate?
Understand the effect of high bounce rate
Bounce rate means the number of people come to your site and doesn’t do anything (no link click, no button click, nothing) and leave your site divided by the total number of people who come to your site.
Case 1: Site loading speed is 3 secs
Suppose your current bounce rate is 20%. You get 1,000 visitors every month and with 20% bounce rate means 200 people leave your site straight away. Now, only 800 people are left to buy your product.
Case 2: Site loading speed is 5 secs
Now, your bounce rate will be increased by 90%. So, 90% of 200 is 180. Which means that total people who’ll leave your site are now 480.
Out of 1,000 visitors you get, 480 straight away leave your site.
Now only 520 are left to buy your product.
How photos affect the loading speed and bounce rate?
Photos are a lot heavier than text.
In 1 KB of text, you can put 1,024 characters. Can 1 KB of the photo has this many characters? No.
Photos are heavier so they take time to load and page loading time increases.
Page loading time increases which increase the bounce rate.
So, there’s a direct relation between the size of the photos and bounce rate. Heavier the photo, higher the bounce rate.
But why are product photos necessary?
75% of Online Shoppers Rely on Product Photos When Deciding on a Potential Purchase. Source
Do you see it? I don’t think that I need to explain to you anymore.
Good Visual Content is 40% More Likely to Get Shared on Your Social Accounts. Source
What is the ideal size of the e-commerce photos?
My company and I edit e-commerce photos (yes, we make your e-commerce photos better by editing them).
From my experience, you should not worry if the total size of the photo is less than 100KB. You also need to make sure that your photo is looking equally beautiful even if it’s only 100KB.
But why 100KB?
Typically, a product has 5 photos. If each photo is 100KB then the total size would be 500KB.
Average net connection speed in the US is 2.33MB per second so loading 500Kb will take less than 0.3 sec. [Source]
The speed also varies by the cities. Kansas City has the fastest net and the average downloading speed there is 19.8MB. [Source]
How can you make photos lesser than 100KB in size?
The answer is “Export As” in Photoshop.
I use this feature all the time. I simply go to File > Export > Export As
I decrease the quality to 50% and dimension to 800 pixels wide.
This normally make the photo only 40-60KB in size which I consider a perfect size.