Free tools, and they're correct
No signup, no email wall, nothing uploaded anywhere. They run in your browser, which is also why they work when your connection does not.
Why these exist
A calculator that is approximately right is worse than none, so the rules behind each one are printed with the answer and dated. Check them. That is the point.
Or let the product do all of this for you.
- Free to start
- No card
- Talk to a person any time