Note: Changes to conversion factors

As of May 2017, changes have been made to some conversion factors used for dairy stocks, trade, and commercial use estimates published in the World Agricultural Supply and Demand Estimates report, the Livestock, Dairy and Poultry Outlook report, and the data file on the ERS Dairy Data page entitled “Commercial disappearance of milk in all products (monthly).” These changes improve estimates of aggregate milk supply and use numbers.  Note the following:

  • All available dairy stock data from the U.S. Dept. of Agriculture, National Agricultural Statistics Service are used in the calculations.  Previously, only certain major dairy products were included.  The additions include stocks of whey products, lactose, canned milk, dry buttermilk, and skim milk for animal use.
  • Conversion factors for stocks account for estimated milk solids in dairy products, not milk solids used to produce products.  Estimates of stocks on a skim-solids basis are substantially lower due to changes in conversion factors for cheese.  However, the reduction is partially offset due to the new inclusion of stocks for whey products and lactose.
  • Historical data for imports and exports of infant formula are changed based upon better information.  The largest changes related to infant formula trade will be reductions in estimates for exports of milk fat.
  • Commercial disappearance of milk in all products has been changed since its calculation depends on stocks and trade data.
  • Under the “Reference tables” heading on the Dairy Data page, a link has been provided to a new reference table entitled "Conversion factors and sources.”  The table is the same as the previous table entitled “Trade conversion factors and sources” with two exceptions:

1. A worksheet has been provided showing conversion factors for stocks and Government removals.

2. Some of the historical import and export conversion factors for preparations for infant use have been changed.


The Dairy Data Set contains files covering various facets of the U.S. dairy industry.  All of the files include data compiled from a variety of sources.


The primary sources of data for the tables:

Calculating commercial disappearance of dairy product categories 

ERS provides commercial disappearance tables for seven product categories: butter, nonfat dry milk, American cheese, other-than-American cheese, dry whey, whey protein concentrate, and lactose. Commercial disappearance tables include total commercial disappearance, domestic commercial disappearance, and the elements that go into calculating commercial disappearance numbers. Monthly data are provided from 1995 to the present.

Relationships are expressed in the following equations:

  • Total commercial supply = beginning commercial stocks + production + imports 
  • Net Government removals [1] = price support purchases through the Dairy Products Price Support Program + exports under the Dairy Export Incentive Program – unrestricted sales of Government stocks 
  •  Total commercial disappearance = total commercial supply – net Government removals – commercial ending stocks 
  •  Domestic commercial disappearance = total commercial disappearance – commercial exports 
Data sources, commercial disappearance for product categories
Commercial disappearance element Source
Commercial stocks 1 USDA, National Agricultural Statistics Service; USDA, Farm Service Agency
Production USDA, National Agricultural Statistics Service
Imports U.S. Department of Commerce, Census Bureau
USDA net government removals  
Price support purchases and unrestricted sales
USDA, Farm Service Agency
Dairy export incentive exports
USDA, Foreign Agricultural Service
Commercial exports 2 U.S. Department of Commerce, Census Bureau; USDA, Foreign Agricultural Service
1 Government stocks are subtracted from total stocks to calculate commercial stocks. NASS reported government stocks through 2007, but has since not published government stock data. A large percentage of government stocks were held by USDA Commodity Credit Corporation (CCC). After 2007, CCC stocks were subtracted from total stocks to estimate commercial stocks.
2 Commercial exports are distinguished from government exports, which include exports that received bonuses under the Dairy Export Incentive Program and foreign donations of government products.

Data sources, commercial disappearance for product categories

Import and export codes used for commercial disappearance product categories

The source for dairy trade data is the U.S. Department of Commerce, Bureau of the Census. U.S. Census Bureau data are compiled using a commodity classification system developed by the World Customs Organization: the Harmonized Commodity Description and Coding System, or simply the Harmonized System (HS). The Harmonized System is an international standard for recording world trade at 2-digit, 4-digit, and 6-digit levels of detail. The United States adopted a 10-digit code system to include greater product detail and began using it for U.S. trade on January 1, 1989. Codes used for U.S. exports are provided in the U.S. Census Bureau Schedule B. Codes used for U.S. imports are provided in the Harmonized Tariff Schedule of the United States (HTS), administered by the U.S. International Trade Commission (USITC). U.S. Census Bureau data for dairy products are reported in kilograms of product weight or liters of product volume. Since ERS commercial disappearance data are reported in pounds, data for imports and exports must be converted to product weight in pounds.

For an Excel workbook displaying import HTS numbers used for each product category, see the "HTS codes used for imports, product categories," under "Reference Tables" on the Dairy Data page. Descriptions listed are those provided by the USITC Interactive Tariff and Trade DataWeb. [2]

For an Excel workbook displaying Schedule B export codes used for each product category, see "HTS codes used for exports, product categories," under "Reference Tables" on the Dairy Data page. Export classification in Schedule B is not nearly as detailed as import classification in the HTS. Note that the distinction between American and other-than-American cheese is not precise. We have categorized HS codes according to what we believe are the predominant varieties of cheeses within each HS classification. For example, we make a simplifying assumption that all processed cheese exported is of an American type.

Calculating commercial disappearance of milk in all products

Four tables are provided for commercial disappearance of milk in all dairy products:

  • Milk-equivalent milk-fat basis
  • Milk-equivalent skim-solids basis
  • Milk fat
  • Skim solids 

Calculation of estimated commercial disappearance of milk in all products is very similar to the calculation for product categories. An exception is the deduction of farm use to estimate milk marketings.

Milk marketings = Milk production – farm use

Total commercial supply = Beginning commercial stocks + milk marketings + imports 

NASS publishes farm use data on an annual basis. To estimate monthly farm use of milk, ERS prorates the annual number grounded on the number of days in each month. For each month in the current year, ERS assumes that farm use is equal to the estimated monthly farm use from the previous year.

Milk is made up of water, milk fat, and skim solids (protein, lactose, ash, and trace elements). Milk equivalents are measured on both a milk-fat basis and a skim-solids basis. The milk-fat and skim-solids content of milk varies from year to year, month to month, cattle breed to cattle breed, and even cow to cow. Most farm milk in the United States averages about 87.5 percent water, 8.8 percent skim solids, and 3.7 percent milk fat.

To account for the supply and use of milk in all products, it is necessary to either account for the equivalent amount of milk or milk solids associated with commercial stocks, imports, exports, and net Government removals of the products. Conversion factors associated with milk fat and skim solids are used for this accounting.

Conversion Factors 

For stocks and Government removals, milk-fat and skim-solids percentages are estimated for each product reported by USDA’s National Agricultural Statistics Service and Farm Service Agency. For imports and exports, milk-fat and skim-solids percentages are estimated for each HS code, based upon information from several sources. To estimate the farm milk equivalent (m.e.) on milk-fat and skim-solids bases, estimated milk fat and skim solids are divided by estimates of milk fat and skim solids in U.S. farm milk, which vary from one month to the next.

National milk fat test data for each month are provided by NASS. A national solids-nonfat (SNF) test based on USDA data does not exist. Therefore, an estimate is created using data reported by USDA’s Agricultural Marketing Service (AMS) and the California Department of Food and Agriculture (CDFA). AMS reports a monthly weighted-average SNF test for Federal milk marketing orders with component-based pricing. California is not included under a Federal Milk Marketing Order but publishes its own SNF test each month. Therefore, a weighted average of the United States SNF test is calculated based on the California data and NASS milk production data:

Weighted monthly U.S. SNF test = { [ (CA monthly SNF test CDFA )  x (CA monthly milk production NASS ) ]

+ [ (Federal Milk Marketing Order monthly SNF test AMS) x ((US monthly milk production NASS )

– (CA monthly milk production NASS))]} / {US monthly milk production NASS }

For an Excel workbook with conversion factors for stocks, Government removals, imports, and exports—as well as the sources for the conversion factors—see "Conversion factors and sources" under "Reference Tables" on the Dairy Data page

As an example, to convert 4,000 kilograms of cheddar cheese imports or exports into a skim-solids basis milk equivalent in a month when skim solids in farm milk equal 8.7 percent, the following formula would be used:

(Product quantity [KG or Liters] x (Metric Conversion Factor) x (Skim percentage)

/ (SNF Test) = Skim-solids basis milk equivalent (4,000 kg of cheese) x (2.204623 pounds/kg) x (29.9 % of skim solids in cheddar cheese)/ (8.7 % of skim solids in farm milk) = 30,307 pounds of m.e. on a skim-solids basis                                 

This number is divided by one million, as commercial disappearance numbers on milk-equivalent bases are published in million pound units.

Commercial Exports, DEIP, and Donations 

Dairy exports through the Dairy Export Incentive Program (DEIP) or U.S. Government donations must be subtracted from total exports reported by the U.S. Census Bureau in order to represent an accurate commercial export figure. ERS has obtained DEIP amounts and U.S. Government donations on a monthly basis starting in 2004. For years before 2004, ERS has only annual estimates of DEIP and Government donations (Government-related exports). Therefore, prior to 2004, ERS has made the simplifying assumption that monthly Government-related exports are the same proportion of total exports for each year. 


The timing of updates is linked to releases of reports by the sources listed above.  Updated monthly tables are usually posted the day after the USDA World Agricultural Supply and Demand Estimates publication. Quarterly U.S. milk production and related data are updated soon after revised data for the last month of the quarter are available.

Historic data

Previously published historical dairy data are available in a Dairy Yearbook accessible through the USDA Economics, Statistics and Market Information System (ESMIS), a collaborative project between the Albert R. Mann Library at Cornell University and several USDA agencies. The Yearbook contains data on production, supply and use of milk and manufactured dairy products, wholesale and retail price indexes, prices received by farmers, milk production costs, and regional shares of U.S. milk production, among other information. The Yearbook was last updated in September 2005. Data contained in archived Yearbooks may not be comparable to the dairy data tables due to subsequent changes in the methodology used to calculate supply and use.

[1] The Dairy Products Price Support Program and the Dairy Export Incentive Program ended on September 30, 2013. 

[2] While the ITC descriptions provided by the USITC Interactive Tariff and Trade DataWeb are useful, they are not as accurate or complete as those in the actual tariff schedule. In the Excel workbooks, DataWeb descriptions are provided instead of the actual HTS descriptions in the interest of brevity.

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Last updated: Thursday, July 13, 2017

For more information contact: Jerry Cessna and Jonathan Law

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