The size of an HTML email can impact both deliverability and subscriber engagement. An email that requires long time to load can lead to lost interest, that’s why it’s important to optimize your emails for better performance.

Acceptable email download speeds according to Email on Acid are:

• 3G connection: Less than 4 seconds
• 4G connection: Less than 3 seconds
• LTE connection: Less than 2.5 seconds
• Desktop connection: Less than 2 seconds

So how can you test your email load speed? The best way to do this, without the need to use third-party vendors or paid software, is to use Google Chrome DevTools.

Testing email download speed in Google Chrome

The first thing you will need to do is to send the email to yourself, and remember to include the View Email as Web Page link in the email body. Click on this link and open your email in Google Chrome Browser.

Next, you will need to open Chrome DevTools. There are several ways to do this:

• press F12
• right-click any element on the page and select Inspect
• press Command+Option+C (Mac) or Control+Shift+C (Windows)

In the DevTools UI, click on the Network tab:

Next, click on No throttling and choose a preset:

Then, refresh the whole page either by clicking the refresh button next to the URL or by pressing F5. You will see how the email loads with all its content elements listed and their download times measured. At the bottom, you will find the final load speed:

Although the available presets do not have an option to use 4G or LTE, you can measure the download speed for 3G and compare it to the benchmark.

If the load time of your email is above the benchmark, you can optimize it by reducing the size of the images (anything above 200KB is considered a large image in email marketing) and by removing unused styles or any unnecessary characters from your code.