Once you know your product's HTS code and its duty rate, calculating what you'll owe at customs is straightforward. But duty rates come in several forms — and each is calculated differently. Here's how to work it out.
The Three Types of Duty Rates
1. Ad Valorem Rates (Most Common)
An ad valorem rate is a percentage of the product's customs value. This is the most common format — for example, 5% or 12.5%.
Formula: Duty = Transaction Value × Rate
Example: You import $10,000 worth of furniture with a 5.3% duty rate. Duty = $10,000 × 0.053 = $530
2. Specific Rates
A specific rate is a fixed amount per unit of weight or quantity — for example, $0.05/kg or ¢1.5/liter.
Formula: Duty = Unit Rate × Quantity
Example: You import 500 kg of a product with a rate of ¢2.2/kg. Duty = 500 × $0.022 = $11
3. Compound Rates
Some products have compound rates that combine both an ad valorem and a specific component. For example: "6.5% + $1.25/kg"
Formula: Duty = (Transaction Value × Ad Valorem %) + (Weight × Specific Rate)
What Is "Transaction Value"?
For customs purposes, the transaction value is generally the price actually paid or payable for the goods when sold for export to the United States. This typically means the invoice price, not including freight and insurance (though customs can require CIF value in some cases). Always check with your customs broker if you're unsure.
What Else Might You Owe?
Customs duty is just one component of the total cost of importing. Depending on your shipment, you may also owe:
- Merchandise Processing Fee (MPF): 0.3464% of the entered value (min $32.71, max $634.62 per entry)
- Harbor Maintenance Fee (HMF): 0.125% of the value (for ocean shipments)
- Section 301 tariffs: Additional tariffs on goods from China
- Anti-dumping / countervailing duties: For certain products from specific countries
A licensed customs broker can provide a full landed cost estimate for your specific shipment.
Important Disclaimer
The duty calculator on LookupHTS is for estimation purposes only. Actual duty owed depends on many factors including valuation method, country of origin, FTA eligibility, and any applicable additional tariffs. Always verify with CBP or a licensed customs broker before filing.