The best font size to use in your email marketing can vary depending on a few factors, such as the font style and design of your email, the purpose of your email, and your target audience.

However, a general rule of thumb is to use a font size between 14 and 16 pixels for the main body text of your email. This font size is large enough to be easily readable on a range of devices, including mobile phones and tablets, while also being small enough to fit more text into your email.

For headings and subheadings, you can use larger font sizes to create visual hierarchy and draw attention to important information. A font size of 20-24 pixels is typically appropriate for headings, while subheadings can be slightly smaller, around 18-20 pixels.

It’s also important to consider the font style you are using, as some fonts may appear smaller or larger than others even if they are set to the same font size. Sans-serif fonts, such as Arial and Helvetica, are generally more readable on screens than serif fonts, such as Times New Roman.

Ultimately, the best font size to use in your email marketing will depend on your specific design and messaging goals, so it’s important to test different font sizes and styles to see what works best for your audience.