A baseline would be making up for the employee's salary reduction with equity. If you're taking VC money then you have some dollar value per share to work from, otherwise base it on 3-5x annual revenue linearly projected from historical monthly revenue.

Formula: (Fair total dollar compensation - agreed salary) / (dollars / share) * 4 yr vesting

A sliding scale for salary : equity is built in and you can compensate based on hire desirability or local market conditions by weighting dollars per share appropriately. This system is fair as long as both the employer and employee agree upon the share value (some information asymmetry there benefiting employers that decent companies will try to correct for).

Saying this as startup first engineer ;)

PGs comments on equity resonate with me, and actually align with what I would have wanted. One of the replies to my original comment actually has the article.

I think the amounts should flow from the right attitude: that they are joining the team to help it succeed, rather than they are being hired to perform a task.