International dollar

The international dollar (int'l dollar or intl dollar, symbols Int'l$., Intl$., Int$), also known as Geary–Khamis dollar (symbols G–K$ or GK$), is a hypothetical unit of currency that has the same purchasing power parity that the U.S. dollar had in the United States at a given point in time. It is mainly used in economics and financial statistics for various purposes, most notably to determine and compare the purchasing power parity and gross domestic product of various countries and markets. The year 1990 or 2000 is often used as a benchmark year for comparisons that run through time. The unit is often abbreviated, e.g. 2000 US dollars or 2000 International$ (if the benchmark year is 2000).

It is based on the twin concepts of purchasing power parities (PPP) of currencies and the international average prices of commodities. It shows how much a local currency unit is worth within the country's borders. It is used to make comparisons both between countries and over time. For example, comparing per capita gross domestic product (GDP) of various countries in international dollars, rather than based simply on exchange rates, provides a more valid measure to compare standards of living. It was proposed by Roy C. Geary in 1958 and developed by Salem Hanna Khamis between 1970 and 1982.

Figures expressed in international dollars cannot be converted to another country's currency using current market exchange rates; instead they must be converted using the country's PPP exchange rate used in the study.

Exchange rate by country

According to IMF, below is the implied PPP rate of International dollar to local currency of respective countries in 2022:

Country	Exchange rate in 2022
Albania	40.22
Algeria	45.28
Andorra	0.59
Angola	228.27
Antigua and Barbuda	2.05
Argentina	67.72
Armenia	161.51
Aruba	1.24
Australia	1.51
Austria	0.74
Azerbaijan	0.67
Bahamas, The	0.81
Bahrain	0.19
Bangladesh	32.11
Barbados	2.31
Belarus	0.96
Belgium	0.77
Belize	1.27
Benin	202.47
Bhutan	20.14
Bolivia	2.51
Bosnia and Herzegovina	0.71
Botswana	4.69
Brazil	2.56
Brunei Darussalam	0.80
Bulgaria	0.79
Burkina Faso	192.77
Burundi	688.36
Cabo Verde	44.33
Cambodia	1332.55
Cameroon	222.10
Canada	1.26
Central African Republic	282.81
Chad	254.59
Chile	460.84
China, People's Republic of	4.10
Colombia	1424.06
Comoros	179.52
Congo, Dem. Rep. of the	1007.08
Congo, Republic of	389.73
Costa Rica	336.75
Croatia	3.29
Cyprus	0.56
Czech Republic	13.38
Côte d'Ivoire	234.62
Denmark	6.63
Djibouti	100.02
Dominica	1.68
Dominican Republic	24.08
Ecuador	0.50
Egypt	4.66
El Salvador	0.46
Equatorial Guinea	337.25
Eritrea	4.69
Estonia	0.60
Eswatini	5.91
Ethiopia	17.03
Fiji	0.83
Finland	0.82
France	0.71
Gabon	352.20
Gambia, The	17.65
Georgia	1.00
Germany	0.72
Ghana	2.71
Greece	0.54
Grenada	1.53
Guatemala	3.88
Guinea	4210.30
Guinea-Bissau	186.19
Guyana	91.64
Haiti	55.74
Honduras	11.03
Hong Kong SAR	5.54
Hungary	153.57
Iceland	148.06
India	23.43
Indonesia	4719.26
Iran	62381.74
Iraq	782.45
Ireland	0.74
Israel	3.51
Italy	0.63
Jamaica	79.79
Japan	90.39
Jordan	0.28
Kazakhstan	172.10
Kenya	43.00
Kiribati	1.09
Korea, Republic of	796.49
Kosovo	0.34
Kuwait	0.23
Kyrgyz Republic	21.74
Lao P.D.R.	3100.29
Latvia	0.53
Lesotho	6.31
Liberia	0.44
Libya	1.52
Lithuania	0.49
Luxembourg	0.85
Macao SAR	4.66
Madagascar	1199.19
Malawi	318.18
Malaysia	1.54
Maldives	7.53
Mali	203.78
Malta	0.55
Marshall Islands	1.11
Mauritania	12.21
Mauritius	16.25
Mexico	9.88
Micronesia, Fed. States of	1.11
Moldova	6.64
Mongolia	1064.79
Montenegro	0.36
Morocco	3.82
Mozambique	23.91
Myanmar	451.68
Namibia	7.18
Nauru	1.27
Nepal	33.56
Netherlands	0.76
New Zealand	1.44
Nicaragua	11.92
Niger	241.31
Nigeria	162.33
North Macedonia	20.06
Norway	11.38
Oman	0.22
Pakistan	44.27
Palau	0.96
Panama	0.45
Papua New Guinea	2.78
Paraguay	2701.54
Peru	1.83
Philippines	18.78
Poland	1.93
Portugal	0.56
Puerto Rico	0.88
Qatar	2.65
Romania	1.92
Russian Federation	32.11
Rwanda	337.15
Saint Kitts and Nevis	1.86
Saint Lucia	1.77
Saint Vincent and the Grenadines	1.46
Samoa	1.83
San Marino	0.63
Saudi Arabia	1.88
Senegal	235.10
Serbia	42.39
Seychelles	7.64
Sierra Leone	3327.59
Singapore	0.83
Slovak Republic	0.50
Slovenia	0.56
Solomon Islands	7.76
Somalia	0.41
South Africa	6.98
South Sudan, Republic of	181.08
Spain	0.59
Sri Lanka	74.82
Sudan	155.65
Suriname	7.46
Sweden	8.73
Switzerland	1.04
São Tomé and Príncipe	10.77
Taiwan	14.91
Tajikistan	2.36
Tanzania	853.89
Thailand	11.71
Timor-Leste	0.46
Togo	223.31
Tonga	1.71
Trinidad and Tobago	4.71
Tunisia	0.95
Turkey	4.23
Turkmenistan	2.21
Tuvalu	1.44
Uganda	1298.23
United Arab Emirates	2.27
United Kingdom	0.67
United States	1.00
Uruguay	30.82
Uzbekistan	2589.68
Vanuatu	121.11
Venezuela	3.52
Vietnam	7174.60
Yemen	447.06
Zambia	6.09
Zimbabwe	356.58

Short description of Geary-Khamis system

This system is valuing the matrix of quantities using the international prices vector. The vector is obtained by averaging the national prices in the participating countries after their conversion into a common currency with PPP and weighing quantities. PPPs are obtained by averaging the shares of national and international prices in the participating countries weighted by expenditure. International prices and PPPs are defined by a system of interrelated linear equations that need to be solved simultaneously. The GK method produces PPPs that are transitive and actual final expenditures that are additive.

Inflation adjusting

When comparing between countries and between years, the international dollar figures may be adjusted to compensate for inflation. In that case, the base year is chosen, and all figures will be expressed in constant international dollars for that specified base year. Researchers must understand which adjustments are reflected in the data (Marty Schmidt):

• Population adjustments (In which case, figures represent per capita monies)
• Currency exchange rate adjustments (In which case, figures will be expressed in one currency unit (typically US$, International $, € £ or ¥)
• Purchasing power parity adjustments and/or average commodity prices (in which case, figures are typically expressed as International $)
• Inflation adjustments (in which case, figures have been adjusted, based on changes in an inflation index such as the consumer price index, to represent currency for a "base" year, such as 2000).

Description of Geary-Khamis system

Suppose PPPj is the parity of j-th currency with a currency called international dollars, which may reflect any currency, however, US dollar is the most commonly used. Then the international price Pi is defined as an international average of prices of i-th commodity in various countries. Prices in these countries are expressed in their national currencies. Geary-Khamis method solves this by using national prices after conversion into a common currency using the purchasing power parities (PPP). Hence, the international price, Pi of i-th commodity is defined as:

$p_{i}={\frac {\left(p_{i1}q_{i1}/{\rm {PPP}}_{1}\right)+\left(p_{i2}q_{i2}/{\rm {PPP}}_{2}\right)+\cdots +\left(p_{iM}q_{iM}/{\rm {PPP}}_{M}\right)}{q_{i1}+q_{i2}+\cdots +q_{iM}}}$

This equation implies that the international price of i-th commodity is calculated by dividing the total output of i-th commodity in all selected countries, converted in international dollars, using purchasing power parities, by the total quantity produced of i-th commodity. Previous equation can be rewritten as follows:

$p_{i}=\sum _{j=1}^{M}{\left(p_{ij}/{\rm {PPP}}_{j}\right){\frac {q_{ij}}{\sum _{j=1}^{M}q_{ij}}}}$

This equation suggests that Pi is weighted average of international prices pij after conversion into international dollars using PPPj. PPPj is by Geary-Khamis system defined through this equation:

${\rm {PPP}}_{j}={\frac {\sum _{i=1}^{N}{p_{ij}q_{ij}}}{\sum _{i=1}^{N}{p_{i}q_{ij}}}}$

The numerator of the equation represents the total value of output in j-th country expressed in national currency, and the denominator is the value of j-th country output evaluated by repricing at international prices Pi in international dollars. Then PPPj gives the number of national currency units per international dollar.

Advantages of Geary-Khamis method

Geary-Khamis international dollar is widely used by foreign investors and institutions such as IMF, FAO and World Bank. It has become so widely used because it made possible to compare living standards between countries. Thanks to the international dollar they can see more trustworthy economic situation in the country and decide whether to provide additional loans (or any other investments) to said country, or not. It also offers some comparison of purchasing power parities all around the world (developing countries tend to have higher PPPs). Some traders even use Geary-Khamis method to determine if country's currency is undervalued or overvalued. Exchange rates are frequently used for comparing currencies, however, this approach does not reflect real value of currency in said country. It is better to include PPP or prices of goods in said country. International dollar solves this by taking into account exchange rates, PPP and average commodity prices. Geary-Khamis method is the best method for comparisons of agricultural outputs.

See also

• World currency
• World currency unit
• Special drawing rights

External links

• Handbook of the International Comparison Programme. Annex II – Methods of Aggregation. Statistical definition at the UN United Nations Statistics Division. 2007
• IMF – Implied PPP conversion rate/National currency per international dollar
• FAO Geary-Khamis statistical yearbook https://www.fao.org/fileadmin/templates/ess/documents/publications_studies/statistical_yearbook/gearyKhamis.pdf
• Brunt, L., Fidalgo, A., (2018) Why 1990 international Geary-Khamis dollars cannot be a foundation for reliable long run comparisons of GDP
• Deaton, A., Heston, A., (2009) Understanding PPPs and PPP-based national accounts https://www.princeton.edu/~deaton/downloads/deaton_heston_complete_nov10.pdf
• Schmidt, M., International Dollar, Geary-Khamis Dollar https://www.business-case-analysis.com/international-dollar.html
• Cuthbert, J., R., Cuthbert, M., (1988) On aggregation methods of purchasing power parities, OECD https://www.oecd.org/economy/outlook/2002058.pdf