[AnotherMarc]

It's hard to say if it's a good offer without knowing how well you're currently being paid compared to market for the salary, and what you would bring to the company. That said, 5% for a senior executive is pretty typical, I think. And I would expect a seed stage company to pay less in salary for a CTO/VPE than a more established company would for the same sort of role (regardless of titles).

You already got some good advice about how to consider equity as part of your total compensation, but that's not what you asked. Hopefully, you've already done some thinking about how much (or little) to value equity yourself. In a vacuum, 5% seems OK for a CTO. If the technology is a critical piece to their business and you have unique expertise in it, you should probably expect more.

[rahimnathwani]

Yours is the only response that has attempted to answer the question which was asked. As you say, the others have focused on how to value the offer, i.e. to compare the salary+equity with an equivalent salary-only offer.

For the OP, Angel List may be a good source of comparative data. It has job postings with salary and equity ranges for similar positions.