The unique Express Delivery, LLC Total Cost Calculator can give you an estimate of what you will have to pay, but its accuracy depends on the information supplied.
An example of a Tax and Duty calculation for an import from the US to the UK would be:
Purchase: Mountain tent US$350 (including local sales tax if applicable)
Merchant's domestic shipping charge = US$100
Total value for Duty US$450 * 20% Duty = Total Duty charge = US$22.50
Total value for VAT calculation is US$372.50 (purchase price + duty payable) with VAT @ 20% for the UK = US$74.50 VAT
The value obtained from the Total Cost Calculator may be higher or lower than the actual total cost due, for example, to differences between estimated and actual currency exchange rates, package weights, product classification or value, and/or volumetric weight calculations for bulky, lightweight packages. See FAQ What is 'volumetric weight'?