Most founders calculate ramen profitability wrong so i built a calculator that fixes the math

Something that bothered me for a while: almost every "ramen profitability calculator" I found online just does total expenses ÷ ARPU. That's it.

But that number has three holes in it:

1. Payment processing: Stripe takes 2.9% + $0.30 per transaction before you see anything. On a $29/mo plan that's $1.14 gone per customer per month before you've paid for a single thing.

2. Variable infrastructure costs: Your database reads, API calls, storage these scale with users. A new customer isn't free to serve.

3. Taxes: If your effective rate is 20-25%, you need to earn significantly more gross revenue to take home your actual survival number. Most calculators just ignore this entirely.

The real formula needs to: compute net contribution margin at the unit level, then gross up your personal expenses to their pre-tax equivalent, then divide.

I built a free calculator that does exactly this: outputs real minimum MRR and exact customer count with a full cash flow waterfall breakdown.

Just launched it on Product Hunt today if anyone wants to check it out or upvote: https://www.producthunt.com/products/ramen-profitability-calculator

Curious what did your ramen number look like before vs after accounting for all three of these? Mine was off by more than I expected.