1 kid.
No need to estimate - we budget and our allocations are tracked per person. Of course, I’m typing this at work so I don’t have the budget in front of me, but a quick and dirty estimate shows that she easily costs $17,000… and I know I’m forgetting some items.
Even more, we let Sophia know how much she costs us, which has proven to be extremely useful. “You want us to buy you that poster? Really - the $52.77/day we spend to maintain your existence in our household isn’t enough? Mind explaining your reasoning, honey?”
This strategy has dramatically cut down on the “I wants” and “Can I have’s” we were peppered with when she was younger.