The Dumping Margin is the amount by which the "normal value" of a product exceeds the "export price" (or "constructed export price") at which it is sold in the United States, expressed as a percentage of the U.S. price. It is calculated by the Commerce Department under 19 U.S.C. § 1677b and 19 CFR § 351.401–351.414.
The basic formula is:
Dumping margin = (Normal Value − Export Price) ÷ Export Price
Normal value is determined in one of three ways, applied in order:
- Home-market sales — Price in the exporter's home market, if a viable market exists (typically when home-market sales are at least 5% of U.S. sales)
- Third-country sales — Price to a comparable third country, if home market is not viable
- Constructed value — Cost of production plus reasonable selling expenses and profit
For non-market economies (currently China, Vietnam, and a handful of others), Commerce uses surrogate-country pricing or cost data instead — driving the substantial separate rate margins seen in many China cases.
The dumping margin is calculated separately for each "mandatory respondent" (usually the two or three largest exporters). Non-mandatory respondents that cooperate may receive a weighted-average all-others rate. Companies that don't cooperate may receive an "adverse facts available" rate — sometimes 100%+ — based on petition data.
Margins are expressed in ad valorem percentages and are recalculated annually during the administrative review.