Every country has different rules on this:

 

1. Most countries have a value threshold before duty applied. For example, the threshold for the USA is $800 USD, and Canada is $20 CAD. 

 

2. The % duty charged depends on the item and the country. There is a free tool you can use to calculate how much duty will be applied to your items. This tool asks for a product description or ‘HS’ code. The code for each product is included with our export documentation, it is referred to as a commodity code on our documents.

https://www.simplyduty.com/import-calculator/