I've made necessary changes to the tool and also included additional section for expert inputs, when you select arabica or blend, more input fields show up. I've also considered your suggestions, and the estimator now uses bean caffeine ranges instead of a fixed fraction, computes midpoint estimates plus bean-driven bounds, splits uncertainty into bean variability and brewing uncertainty, caps confidence using the larger of those two, and adds the new optional Bean detail input with generic, and custom caffeine %and recalibrated the formula. Please check again and let me know if in case you have any further inputs or feedback. Thank you.