tried it to the US and it is not quite accurate. Leaves out a lot of exemptions, fees are incorrect, and generally is too vague. Rates are also sometimes based on mode of transportation. What comes in as personal baggage on a trip is a lot different than mail for example. Products are also many times are classified based on interpretation from the officer calculating the duty. not so cut and dry as this calculator has you thinking. Something like a bicycle can have numerous duty rates based on frame material, country of origin, size, use (road/mtn), kids or adults, wheel size, etc.....
Your best bet is to call your local customs office and ask. Stop relying on unauthorized internet calculators and forums to get answers. There are a lot of myths & assumptions out there and what happens to some is not necessarily what may happen to you.