How to Calculate Import Tariffs Step by Step: The 2026 Guide
In 2026, calculating a US import tariff is not "look up one number." It is a layered calculation involving up to 5 tariff layers plus 2 federal fees, each with their own rules, exemptions, and country-specific carve-outs. This guide walks through the math step by step so you can do it on a napkin if you have to.
The master formula
Total Duty + Fees = (Goods Value × Σ applicable rates) + MPF + HMFWhere:
- Goods Value = transaction value (what you paid the seller)
- Σ applicable rates = sum of base MFN + Section 301 + Section 232 + IEEPA + reciprocal baseline (each layer only applies if your product and origin qualify)
- MPF = Merchandise Processing Fee (0.3464%, capped $32.71–$634.62)
- HMF = Harbor Maintenance Fee (0.125%, sea freight only)
The 6-step process
Step 1 — Determine the customs value
Use the transaction value: actual price paid plus any assists, royalties, license fees, and packing costs. Exclude international freight and insurance when listed separately on the invoice. See our Incoterms guide for what's included under each Incoterm.
Step 2 — Find your 10-digit HTS code
Your HTS code determines the base MFN duty and which tariff layers apply. Use hts.usitc.gov to look up your specific code.
Step 3 — Determine country of origin
Country of origin determines whether Section 301 (China), IEEPA (Mexico/Canada), or the reciprocal baseline applies. See our country of origin guide.
Step 4 — Identify applicable tariff layers
| Layer | When it applies |
|---|---|
| Base MFN duty | Always — from HTS column 1 |
| Section 301 | Chinese-origin goods on USTR Lists 1-4 |
| Section 232 | Steel, aluminum, autos, semiconductors, pharma — see Section 232 guide |
| IEEPA | Mexico, Canada (non-USMCA-qualifying) |
| Reciprocal baseline | Most countries; replaced by Section 232 where it applies |
| AD/CVD | Product-specific orders — see AD/CVD guide |
Step 5 — Calculate the layers
Each layer = Goods Value × rate. Sum them.
Step 6 — Add federal fees
- MPF = max(min(Goods Value × 0.3464%, $634.62), $32.71)
- HMF = Goods Value × 0.125% (sea freight only; 0 for air)
Real example: $25,000 of consumer electronics from China, by sea
| Step | Calculation | Result |
|---|---|---|
| Goods value | — | $25,000 |
| Base MFN duty | HTS 8517.13 column 1 = 0% | $0 |
| Section 301 (List 4A) | $25,000 × 25% | $6,250 |
| Section 232 | Doesn't apply | $0 |
| IEEPA | Doesn't apply (not MX/CA) | $0 |
| Reciprocal baseline (China 30%) | $25,000 × 30% | $7,500 |
| MPF | min($25,000 × 0.3464%, $634.62) = min($86.60, $634.62) | $86.60 |
| HMF | $25,000 × 0.125% | $31.25 |
| Total duty + fees | — | $13,867.85 |
| Effective rate on goods | — | ~55.5% |
Quick mental shortcuts
- For Chinese consumer goods: base MFN + 25% Section 301 + 30% reciprocal ≈ 55-60%
- For Chinese steel/aluminum: 50% Section 232 + 25% Section 301 ≈ 75% (reciprocal doesn't stack on top of Section 232)
- For USMCA-qualifying Mexican/Canadian goods: 0% on most categories
- For Vietnamese goods: base MFN + 20% reciprocal (no Section 301)
- For EU goods: base MFN + 15-20% reciprocal (+ 25% if autos)
Tools that do the math for you
- Our free import duty calculator — handles all layers automatically for the most common scenarios
- USITC's HTSUS — for the official base MFN rate and column changes
- USTR Section 301 list lookup — for the China-specific layer
- Your customs broker — should run the full calculation as part of their fee
Common mistakes
- Using FOB value instead of transaction value. If freight is bundled into the price (CIF, DDP), you need to back it out.
- Forgetting the MPF minimum. Small shipments still pay $32.71 minimum MPF.
- Stacking reciprocal on top of Section 232. Reciprocal baseline is replaced by, not added to, Section 232 for metals and autos.
- Missing AD/CVD orders. If your product is subject to an order, that rate adds 10-400%+ on top.
- Not checking USMCA qualification. The single biggest cost-saving check for Mexican/Canadian goods.
Frequently asked questions
What is the formula for calculating US import duty?
Total Duty + Fees = (Goods Value × Σ applicable rates) + MPF + HMF. Rates include base MFN, Section 301, Section 232, IEEPA, and reciprocal baseline depending on origin and product.
What value do I use for calculating duty?
Transaction value — what you paid the seller — plus assists, royalties, packing, but excluding international freight and insurance when separately stated.
Does the MPF cap apply per shipment or per entry?
Per formal entry. The $634.62 cap means high-value shipments don't pay proportional MPF.
Why does my calculator say more than yours?
Possible reasons: AD/CVD on your product, you used CIF instead of transaction value, or your HTS code is in a higher-tariff category than you think.
Do I add reciprocal baseline AND Section 232?
No, they don't stack. Reciprocal is replaced by Section 232 for steel, aluminum, autos, and most other Section 232 categories.
How do I find my specific HTS code?
Use the USITC HTS lookup at hts.usitc.gov or read our HTS code guide.