I see a lot of “rules of thumb” suggestions in the comments (% of income, match Google/employer, etc.). I disagree with these approaches.
I recommend that you spend the requisite time to create a detailed projection of your cash flow. Try to determine how you want to use every dollar you will ever have.
A probabilistic projection will return an optimal giving range. The range may be wide, but at the very least I think this exercise will help you identify upper and lower boundaries.
Added bonus - It’s a great way to take account of your true priorities.
I'd like to hear from people about a process they use to decide how much to give to charity. Personally, I have very high income, and while we donate significant money in absolute terms, in relative terms the amount is <1% of our post-tax income. It seems to me that it's too little, but I have no moral intuition as to what the right amount is.
I have a good intuition on how to allocate the money, so that's not a problem.
Background: I have a wife and two kids, one with significant health issues (i.e. medical bills - possibly for life), most money we spend goes to private school tuition x 2, the above mentioned medical bills, mortgage, and miscellaneous life expenses. And we max out retirement savings.
If you have some sort of quantitative system where you figure out how much to spend on charity, please share. If you just use vague feelings, and you think there can be no reasonable quantitative system, please tell me that as well.
Update: as suggested in the comments, I'll make it more explicit: please also share how you determine how much to give.