Type what you are importing in everyday words. Each page gives the 6-digit HS code by fabric and by knit or woven, the full UK, US and EU tariff lines, and the reasoning customs uses, with official sources. Then see the import duty for that garment in 60 countries.
The first 6 digits are the same in every country that uses the Harmonized System. Countries then add their own digits: the UK and EU use 8 or 10 (CN8 / commodity code), the US uses 8 for the duty rate (HTS) and 10 for statistics. For garments, two things decide the code: whether the fabric is knitted (Chapter 61) or woven (Chapter 62), and which fibre is the largest by weight.
Indicative classification from the official UK, US and EU tariffs and published customs rulings, as checked on the date shown. It is not a binding ruling: the importer is responsible for the code declared, and a binding tariff information (BTI/ATaR) or a CBP ruling gives certainty.