U.S. R&D expenditures can be compared with those of other countries to illustrate the relative position of the United States in this area and its impact on economic and other national goals noted earlier. Statistics in this section cover available data from MSTI (OECD 2023c) and are reported in U.S. dollars using purchasing power parity (PPP). PPP converts different currencies to a common currency while adjusting for differences in price levels between economies, allowing for cross-country comparisons.

Based on internationally comparable estimates, the United States reached $806.0 billion in gross domestic expenditures on R&D (GERD) in 2021 ($709.7 billion in constant U.S. PPPs), up 10% from 2020 (6% in constant PPPs).^{​U.S. GERD as reported by OECD differs slightly from the U.S. total domestic R&D performance tabulated earlier in this report. For consistency with international standards for the measurement of GERD, OECD includes U.S. domestic expenditures on capital for R&D, excludes depreciation on U.S. domestic R&D capital, and makes certain adjustments for foreign sources of funding of domestic R&D.U.S. GERD as reported by OECD differs slightly from the U.S. total domestic R&D performance tabulated earlier in this report. For consistency with international standards for the measurement of GERD, OECD includes U.S. domestic expenditures on capital for R&D, excludes depreciation on U.S. domestic R&D capital, and makes certain adjustments for foreign sources of funding of domestic R&D.} China, the second-highest performer of domestic R&D in recent years, totaled $667.6 billion in 2021 ($620.1 billion in constant PPPs), up 14% from 2020 (10% in constant U.S. PPPs) (OECD 2023c). Other top R&D performers include Japan ($177.4 billion), Germany ($153.7 billion), South Korea ($119.6 billion), the United Kingdom ($97.8 billion), and France ($77.2 billion) in current U.S. PPP dollars (Figure RD-8, Figure RD-9; Table SRD-1).

The distribution of R&D within countries presents some cross-sectional features. The business sector is the largest performer and funder of R&D across the top R&D-performing countries (Table RD-4). Across all countries with available statistics, Israel, Taiwan, and Ireland had the largest shares of R&D performed by the business sector (Table SRD-2). The government sector in many countries, including Germany and China, performed a higher share of R&D than the U.S. government sector (15% in Germany and China, compared with 8% in the United States, based on OECD GERD estimates). The R&D performance share of higher education was at least 20% in the European Union (EU-27), the United Kingdom, and France, compared with single-digit shares in China and South Korea. Table RD-4 also shows that government funded approximately 30% of R&D in Germany and France, driving the EU-27 overall share funded by this sector to 31%, compared with 20% and 19%, respectively, for the United States and China.^{​For international comparative measures of other forms of R&D support by governments such as tax incentives, see the OECD INNOTAX Portal (OECD 2023f).For international comparative measures of other forms of R&D support by governments such as tax incentives, see the OECD INNOTAX Portal (OECD 2023f).}

Based on available statistics across countries, the global total for R&D expenditures was $2.6 trillion in U.S. current PPP dollars in 2021. This includes all 37 OECD members plus another 7 economies (Argentina, China, Romania, Russia, Singapore, South Africa, and Taiwan) available in the OECD R&D database (Table SRD-1).^{​The global total is based on 2021 or, for countries with missing data in the OECD database, the latest available year. In contrast with previous editions of this report, comparable data on R&D were not available from the United Nations Educational, Scientific and Cultural Organization database, where most non-OECD R&D statistics were obtained.The global total is based on 2021 or, for countries with missing data in the OECD database, the latest available year. In contrast with previous editions of this report, comparable data on R&D were not available from the United Nations Educational, Scientific and Cultural Organization database, where most non-OECD R&D statistics were obtained.} The global total for the same set of economies in 2018 was $2.1 trillion, for a CAGR of 7.8% in U.S. current PPP dollars from 2018 to 2021 (OECD 2023c).

Overall, the top 5 R&D-performing economies (the United States, China, Japan, Germany, and South Korea) accounted for 73% of the 2021 total, the top 10 for 85%, and the top 20 for 93% (Figure RD-8; Table RD-5; Table SRD-1).^{​For methodological information on updated country statistics, see OECD (2023g).For methodological information on updated country statistics, see OECD (2023g).} The EU-27 accounted for 18% of global GERD in 2021 (OECD 2023c). China’s GERD grew annually by double digits (nominal CAGR) in 2000–10 (20.5%) and in 2010–21 (11.0%), exceeding the rate of GDP growth over each of these periods, measured in U.S. current PPP dollars based on OECD MSTI statistics (Table RD-5). For the United States, the CAGR for GERD between 2000 and 2010 was 4.3%, compared with a growth rate of 3.9% for GDP over that period. For 2010–21, U.S. GERD grew 6.4% annually in nominal CAGR terms, faster than the nominal GDP growth rate of 4.1%.

The GERD-to-GDP ratio facilitates comparisons of national investment in R&D relative to the size of the economy across countries and time (Figure RD-8, Figure RD-10). This indicator may be grouped into three size categories. Only two countries, Israel and South Korea, had R&D intensities above 4.0% in 2021 (Table SRD-1). Eight economies had intensities between 3.0% and 4.0%, including Taiwan (3.8%), the United States (3.5%), Japan (3.3%), and Germany (3.1%). And multiple countries had intensities above 2.0%, including the United Kingdom at 2.9%, China at 2.4%, France at 2.2%, and Singapore at 2.2%. The EU-27 had a ratio of 2.2% in 2021, compared with 1.9% in 2010.