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Explanation of "Developments in Real Exports and Real Imports"

May 2026
Bank of Japan
Research and Statistics Department

Basic Information

Compilation section: Economic Research Division, Research and Statistics Department

Frequency of compilation: Monthly basis

Time of release: One business day after the release day of the "Trade Statistics (Provisional)"

Method of release: Bank of Japan's website

Commencement of data: January 1975 (January 2000 for Real exports by region and by goods)

1. Content

(1) Purpose and Function

Real Exports and Real Imports are calculated by dividing the Nominal Export and Nominal Import Values of goods, which are released in the Ministry of Finance's "Trade Statistics," by the Export and Import Price Indexes released by the Bank of Japan.

Real Exports and Real Imports, which are calculated by dividing the nominal value by the price index, represent movements of exports and imports in real terms by eliminating the effects of price changes.

(2) Release Data

The following series are seasonally adjusted and released on a monthly basis:

  • Real exports (CY 2020 = 100, since 1975)
  • Real imports (CY 2020 = 100, since 1975)
  • Real exports by region (CY 2020 = 100, since 2000)
  • Real exports by goods (CY 2020=100, since 2000)

Data for Real exports by region include figures for "United States," "EU,"1 "China," "NIEs, ASEAN, etc.,"2 and "Other economies." Data for Real exports by goods include figures for "intermediate goods," "motor vehicles and related goods,"3 "IT-related goods,"4 "capital goods,"5 and "other goods." For reference, Real exports excluding "other goods" are also published, given that "other goods" includes re-exported goods that are not included as goods exports in the GDP statistics.

Notes:

  1. Does not include the United Kingdom for the entire period.
  2. Includes other Asian countries such as India and Bangladesh.
  3. Includes motor vehicles, parts of motor vehicles, and power generating machine.
  4. Includes computers and units, telecommunication machinery, semiconductors,
    audio & visual apparatus, and medical and optical instruments.
  5. Includes metalworking machinery, construction machines, electrical power machinery, semiconductor machinery, and ships.

(3) Methodology

A. Real Exports

First, the total nominal value of exports is broken down into 31 items, referring to the principal commodity classifications in the "Trade Statistics" released by the Ministry of Finance. Next, they are summed up after figures in each item are deflated by the corresponding deflators. They are then seasonally adjusted and indexed so that the annual averages of those figures in the year 2020 are equal to 100.

In principle, the Export Price Index (EPI), released by the Research and Statistics Department of the Bank of Japan, is used for export deflators.

Due to data limitations and other constraints, data prior to 2000 are retroactively revised using the month-on-month rates of change in the data compiled with the eight-group deflation method, which divides the nominal export value into eight groups based on the classifications in the "Trade Statistics," deflating each group using the corresponding deflator, and then aggregating.

B. Real Imports

First, the total nominal value of imports is broken down into 28 items, referring to the principal commodity classifications in the "Trade Statistics" released by the Ministry of Finance. Next, they are summed up after figures in each item are deflated by the corresponding deflators. They are then seasonally adjusted and indexed so that the annual averages of those figures in the year 2020 are equal to 100.

The Import Price Index (IPI), released by the Research and Statistics Department of the Bank of Japan, is used for import deflators.

Due to data limitations and other constraints, data prior to 2000 are retroactively revised using the month-on-month rates of change in the data compiled with the eight-group deflation method, which divides the nominal import value into eight groups based on the classifications in the "Trade Statistics," deflating each group using the corresponding deflator, and then aggregating.

For detailed information on the correspondence between items and deflators used in the calculation of Real exports and Real imports, please refer to "Goods Classification in Real exports and Real imports [PDF 91KB]."

(4) Base Year for the Deflator

The base year for the deflator is 2020 (2020 prices).

(5) Seasonal Adjustment of Real Exports and Real Imports

The X-12-ARIMA procedure is used for seasonal adjustment. Updating the seasonal adjustment takes place every year around April by using all available time series. Until the next update, the seasonally-adjusted figures are calculated using expected seasonal factors. Details on the seasonal adjustment method of Real Exports and Real Imports are as follows:

  • The ARIMA parts of the model are: (112)(011) for Real Exports and (011)(011) for Real Imports.
  • The forecast using the ARIMA model is extended up to 48 months (backcasting is not conducted).
  • Trading days, holidays, and leap-year effects are adjusted using user-defined variables, which are based on the number of business days at customs clearance in Japan, etc.
  • Outliers are automatically detected/adjusted in estimating regARIMA models (level shifts and ramps are not adjusted).

(6) Time of Release

Data are, in principle, released at 4:00 p.m., one business day after the release of "Trade Statistics (Provisional)." Please note that the release schedule is subject to change.

2. Related Materials

Details are available in the following research paper.