Tools

Calculators, not
another tool listicle.

Each of these takes your numbers and runs a model that is documented in the accompanying post — the same arithmetic, not a simplified version of it. They run entirely in your browser. Nothing you type is sent anywhere, and none of them ask for an email.

This page used to be a list of software I recommend. That is a page an AI summary can replace in one paragraph, so it is gone. A calculator that takes your own inputs is not.

These are the demo versions

Every default in here is illustrative. The models get useful when they are fitted to your own data — your measured redemption hazard, your real margin, your actual conversion rate — because that is when the output stops being a sanity check and starts being a decision.