Crudely, if my aunt had a dick she'd be my uncle.

In terms of feedback: - need BTC prices pre 2014 to really feel the pain - The date format for earliest date available is different to the date format then used in the input below

You are 100% right about pre-2014 BTC. Any suggestion where to download trusted prices?

Regarding the date format - it can really cause confusion. Let me explaine. The "calculator" date format is "YYYY-MM-DD" (ISO 8601). But the input field's date format adapts based on your device settings. For better UX.