GDP 計算ツール
The detailed guide below is currently available in English.
The expenditure approach
GDP can be read from who buys the output: households (consumption), firms (investment), and governments purchase what is produced at home, while exports add foreign demand and imports subtract spending that leaked abroad. Adding the pieces, GDP = C + I + G + (X − M), accounts for every final good and service exactly once — imports are already inside C, I, and G, so they are backed out through net exports.
Nominal versus real GDP
The headline figure sums everything at today's prices, which makes it nominal. If prices rise while nothing else changes, nominal GDP rises too. Statisticians therefore compute real GDP by valuing each year's output at the prices of a fixed base year; the gap between the two is the GDP deflator, a broad measure of inflation.
よくある質問
What counts as investment in GDP?
Business equipment, structures, and inventories — spending that creates future productive capacity. Buying existing shares or a used house is a transfer of ownership, not new output, so it is excluded.
Why are imports subtracted?
Imported goods are part of consumption, investment, and government purchases when bought, but they were not produced domestically. Subtracting them leaves only home-produced output in the total.
Can net exports be negative?
Yes. A trade deficit simply means the country spent more abroad than it sold abroad; the negative net-export figure reduces GDP but does not make the calculation invalid.