How to Calculate Import Duty and Tariff Cost
Import duty is not a single number you look up — it is the result of several inputs applied in order. This guide walks through each input, shows the normal calculation sequence, and works a fully labelled example using clearly assumed rates.
Reviewed by Onno C. P. Boots, publisher of UtilityPilot · Last reviewed: 4 September 2026
The inputs you need
- Product classification — the HS/HTS code that sets the duty rate.
- Country of origin — where the goods were made, which can change the rate.
- Importing country — the country charging the duty.
- Customs value — the value duty is charged on (see the customs value guide).
- Duty rate — the percentage or specific rate from the tariff schedule.
- Additional tariffs — anti-dumping, safeguard or trade-remedy measures, where they apply.
- Import VAT/GST — a separate tax charged on top of duty in many countries.
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The normal calculation sequence
- Classify the product to get the duty rate.
- Establish the customs value (often transaction value, sometimes plus freight and insurance, depending on the country).
- Apply the duty rate to the customs value to get the duty amount.
- Add any additional tariffs that apply.
- Work out the import-tax base, then apply import VAT/GST.
- Add the duty, additional tariffs and import tax to get total border charges.
Duty vs import tax
Duty is a charge tied to the product’s classification and origin. Import VAT or GST is a consumption tax charged on the value of the goods, usually calculated on a base that already includes the duty. They are separate charges with separate rules, and confusing the two is one of the most common estimating errors.
Worked example (assumed figures)
The rates below are illustrative assumptions, not current official rates. Always verify the applicable duty and tax rates with the official tariff authority for your import.
| Customs value | 10,000 |
| Assumed duty rate | 5% |
| Duty amount (5% of 10,000) | 500 |
| Assumed additional tariff (2%) | 200 |
| Import-tax base (10,000 + 500 + 200) | 10,700 |
| Assumed import tax (10% of 10,700) | 1,070 |
| Total border charges (500 + 200 + 1,070) | 1,770 |
The sequence matters: because import tax here is charged on a base that already includes duty and the additional tariff, changing the duty rate changes the tax as well.
Common mistakes
- Applying duty to the invoice price when the country requires freight and insurance in the customs value.
- Forgetting import VAT/GST, which is often larger than the duty itself.
- Charging import tax on the goods value only, when it should sit on a duty-inclusive base.
- Using an out-of-date or wrong-origin duty rate.
- Ignoring additional trade-remedy tariffs that apply to specific goods and origins.
What UtilityPilot can calculate
Enter a customs value and a verified duty rate into the tariff calculator and UtilityPilot applies the sequence above, showing duty, additional tariffs and import tax separately. If you do not yet have a classification, start with the HS finder.
What you must verify
The duty rate, any additional tariffs and the import-tax treatment all depend on your exact classification, origin and destination. Verify them with the official authority; UtilityPilot does not supply live official rates or issue binding decisions.
Official sources
UtilityPilot summarises these authorities in its own words. Always verify duty rates and classifications directly with the relevant authority before filing a customs entry.
- USITC Harmonized Tariff Schedule — The official US HTS: full national tariff lines and general duty rates. (United States)
- U.S. Customs and Border Protection — Entry procedures, valuation, additional duties and rulings guidance. (United States)
- European Commission TARIC — EU integrated tariff: duty rates, measures and trade-defence duties by CN code. (European Union)
- UK Trade Tariff — UK commodity codes, duty rates, VAT and preferential rates. (United Kingdom)
Source registry last updated: 4 September 2026
UtilityPilot helps you organise and estimate import costs. It does not issue binding customs classifications and does not supply live official tariff rates. Verify the final classification and duty rate with the official authority or a licensed customs broker.