We think that the “best conversion rate” is any number higher than what you’re currently doing. Even a one percent bump in conversion will take your business to the next level. Broadly speaking, a common conversion rate for an email opt-in landing page is between 5% and 15%. The companies with the most success tend to convert at around 20-25%. And the very cream of the crop achieves conversion rates of 30% or higher.
But, in a lot of respects, these numbers are arbitrary. You’ll get a lot of “expert advice” on the number that will show success or not. For the most part, these numbers are too general to be helpful.
All in all, it’s up to you to decide the right conversion rate for your website.
Please have a look at this tutorial on how you can optimize your conversion: https://www.leadpages.com/conversion-optimization-guide/what-is-a-good-conversion-rate