How to Calculate Import Duty
US import duty is not a single tax — it's a stack of rates multiplied by your product's customs value, then layered with fees. Get any component wrong and you're either handing money to CBP unnecessarily or facing a penalty audit.
TL;DR: Import duty = (customs value × HTS MFN rate) + Section 301 if from China + MPF (0.3464%) + HMF (0.125% ocean). The calculator at the bottom does all of this for 70+ countries in under 10 seconds.
Total Import Duty =
(Customs Value × MFN Rate)
+ (Customs Value × §301 Rate) China only
+ (Customs Value × §232 Rate) steel/aluminium
+ (Customs Value × 0.3464%) MPF
+ (Cargo Value × 0.125%) HMF (ocean)
Step-by-Step: Calculating US Import Duty
Classify your product with an HTS code
The US Harmonized Tariff Schedule (HTS) assigns every imported product a unique 10-digit code. The first 6 digits follow the international HS system; the last 4 are US-specific. Your duty rate is tied to this code — misclassify and you either overpay or face a penalty audit.
Use Zentria Flow's free AI HS code tool or search USITC Dataweb. When in doubt, request a Binding Tariff Information (BTI) ruling for certainty.
Establish the customs value
The customs value is generally the transaction value — the price you paid (or will pay) for the goods, expressed in USD. For FOB terms, this is your invoice price. For CIF terms, subtract the international freight and insurance charges to get the FOB customs value.
If related-party pricing applies (buying from your own factory), CBP may scrutinize the transaction value. First-sale valuation can often reduce it legally.
Apply the MFN base duty rate
Multiply the customs value by the Most-Favored-Nation (MFN) duty rate listed in the HTS for your product. This is the standard rate for goods from WTO member countries. Rates range from 0% (many industrial goods) to 20%+ (apparel, footwear, some food products).
Check for free trade agreement rates. USMCA, CAFTA-DR, and US-Korea FTA can reduce the rate to 0% if origin requirements are met.
Add Section 301 China surcharges (if applicable)
If your goods originate in China, you must add Section 301 tariffs. Lists 1–3 carry 25%, List 4A 7.5%, and the suspended List 4B 0%; the four-year review raised some products to 25–100% (chips, EVs, batteries, medical goods). Since 24 July 2026 goods from China and 59 other economies also pay the forced-labor Section 301 tariff (10–12.5%), unless exempt or covered by Section 232.
Country of origin is determined by the last substantial transformation, not where you purchased the goods. Goods assembled in Vietnam from Chinese components may still attract §301.
Add Section 232 tariffs for steel and aluminium
Steel mill products carry a 25% tariff and aluminium products carry a 10% tariff under Section 232, applied to most countries. Some countries (Canada, Mexico under USMCA) have quota-based exemptions. This applies to the product itself, not packaging.
Downstream articles containing steel or aluminium may be subject to derivative §232 tariffs. Check if your product falls under HTS Chapter 73 or 76.
Calculate the Merchandise Processing Fee (MPF)
MPF is charged on most formal entries: 0.3464% of the customs value, with a minimum of $34.58 and a maximum of $670.86 per entry (FY2027). Informal entries up to $2,500 pay a flat $2.77. Goods qualifying under USMCA (Canada, Mexico) are exempt from MPF.
MPF is per-entry, not per-shipment. Consolidating multiple purchase orders into a single entry can reduce MPF if values are similar.
Add Harbor Maintenance Fee (HMF) for ocean imports
Ocean shipments through US commercial ports pay HMF: 0.125% of the cargo value. Air freight, truck imports from Canada/Mexico, and certain inland waterway shipments are exempt.
HMF applies to the cargo value (typically CIF), not just the customs value. For large ocean shipments, this can add hundreds of dollars.
Sum all components
Total import duty = base MFN duty + §301 (if China) + §232 (if steel/aluminium) + MPF + HMF. Add this to your product cost, freight, insurance, and brokerage to get your full landed cost.
Don't forget anti-dumping (ADD) and countervailing duties (CVD) for certain products and countries — solar panels, steel, tyres, and seafood are common targets.
Worked Example: Activewear from China
Importing $15,000 of polyester activewear tops from China via ocean freight. HTS 6110.30.30 carries a 32% MFN duty rate.
2026 Tariff Alert
Section 301 rates on Chinese goods were raised for some products in 2024–2026, the IEEPA tariffs were struck down in February 2026, and the forced-labor Section 301 tariff took effect on 24 July 2026. Always verify current rates before making sourcing decisions — static spreadsheets go stale quickly.
Example Duty Rates by Product (2026)
Frequently Asked Questions
Who pays import duty — buyer or seller?
Under standard Incoterms, the importer of record (usually the buyer) pays customs duty, MPF, and HMF. Under DDP (Delivered Duty Paid) terms, the seller pays. Always clarify Incoterms in your purchase contract before finalizing prices.
Is there a minimum order value before customs duty applies?
There is no US de minimis any more. The $800 exemption was suspended for every country on 29 August 2025 and CBP made that a regulation in 2026; Congress repeals it outright from July 2027. Every shipment owes duty; orders up to $2,500 can use an informal entry with a flat $2.77 processing fee.
How do I avoid paying import duty legally?
Legal duty reduction strategies include: using an applicable FTA (USMCA, CAFTA, etc.), bonded warehouses or Foreign Trade Zones, duty drawback on re-exported goods, first-sale valuation for multi-tier supply chains, and strategic HTS classification reviews. Never misclassify goods — penalties can exceed 4× the unpaid duty.
Does import duty apply to samples?
Samples imported for commercial purposes are dutiable at the same rate as commercial goods. However, low-value samples ($1 per item, permanently marked) may qualify as 'articles of negligible value' and enter duty-free under HTS 9811.00.60.
Related guides
Disclaimer: Rates and calculations are advisory. US Customs and Border Protection makes final duty determinations at time of entry. Consult a licensed customs broker for binding classification or valuation decisions.