| Tue, May 1 | Labor Day / May Day | Multiple Countries | Multiple Types |
| Tue, May 1 | Labor Day | Multiple Countries | Multiple Types |
| Tue, May 1 | May Day | Multiple Countries | Multiple Types |
| Tue, May 1 | Labour Day | Multiple Countries | Multiple Types |
| Tue, May 1 | Labor and Solidarity Day | Turkey | National Holiday |
| Tue, May 1 | National Workers Day | Saint Vincent And The Grenadines | Public Holiday |
| Tue, May 1 | Labour Day/May Day | Multiple Countries | National Holiday |
| Tue, May 1 | International Workers' Day | Eritrea | Public Holiday |
| Tue, May 1 | Spring and Labor Day | Russia | National Holiday |
| Tue, May 1 | Law Day | United States | Observance |
| Tue, May 1 | Loyalty Day | United States | Observance |
| Tue, May 1 | Feast of St Joseph the Worker | Holy See (vatican City) | National Holiday |
| Tue, May 1 | Imam Mahdi's birthday | Iran | National Holiday |
| Tue, May 1 | International Labour Day | Kosovo | Official Holiday |
| Tue, May 1 | Workers Day | Zimbabwe | Public Holiday |
| Tue, May 1 | International Labor Day | Multiple Countries | Public Holiday |
| Tue, May 1 | May 1st | Sweden | Public Holiday |
| Tue, May 1 | Worker's Day | Multiple Countries | Public Holiday |
| Tue, May 1 | Unity Day | Kazakhstan | Public Holiday |
| Tue, May 1 | Labor holiday | Serbia | National Holiday |
| Tue, May 1 | Prayer Day | Faroe Islands | Public Holiday |
| Tue, May 1 | Labor day | Multiple Countries | Multiple Types |
| Tue, May 1 | Agriculture and Labor Day | Haiti | National/legal Holiday |
| Tue, May 1 | Workers' Day | Multiple Countries | Public Holiday |
| Tue, May 1 | International Day of Solidarity of Workers | Moldova | National Holiday |
| Tue, May 1 | Maharashtra Day | India | State Holiday |
| Wed, May 2 | Labor Day Holiday | Ukraine | National Holiday |
| Wed, May 2 | Labor Day (Day 2) | Bosnia And Herzegovina | Public Holiday |
| Wed, May 2 | Day of Madrid | Spain (Madrid) | Local Holiday |
| Wed, May 2 | Labor holiday second day | Serbia | National Holiday |
| Wed, May 2 | Labour Day holiday | Multiple Countries | National Holiday |
| Wed, May 2 | Labour Day/May Day (day 2) | Montenegro | National Holiday |
| Thu, May 3 | Lag B'Omer | Multiple Countries | Multiple Types |
| Thu, May 3 | Lag BaOmer | United States | Jewish Holiday |
| Thu, May 3 | National Day of Prayer | United States | Observance |
| Thu, May 3 | Cross Day | El Salvador | Observance |
| Thu, May 3 | Constitution Day | Poland | National Holiday |
| Thu, May 3 | Constitution Memorial Day | Japan | National Holiday |
| Thu, May 3 | World Press Freedom Day | Multiple Countries | International |
| Fri, May 4 | Anniversary of the Decease of M. R. ŝtefánika | Slovakia | Observance |
| Fri, May 4 | Kent State Shootings Remembrance | United States (Ohio) | Local Observance |
| Fri, May 4 | Rhode Island Independence Day | United States (Rhode Island) | Local Observance |
| Fri, May 4 | Remembrance Day | Netherlands | Observance |
| Fri, May 4 | Literary Day | Taiwan | Observance |
| Fri, May 4 | Greenery Day | Japan | National Holiday |
| Fri, May 4 | Youth Day | China | Observance |
| Fri, May 4 | Independence Restoration Day | Latvia | National Holiday |
| Fri, May 4 | Cassinga Day | Namibia | Public Holiday |
| Fri, May 4 | No Pants Day | Multiple Countries | Unofficial |
| Sat, May 5 | Battle of Puebla | Mexico | Observance |
| Sat, May 5 | Constitution Day of the Kyrgyz Republic | Kyrgyzstan | Public Holiday |
| Sat, May 5 | Europe Day | Germany | Observance |
| Sat, May 5 | Cinco de Mayo | United States | Observance |
| Sat, May 5 | National Explosive Ordnance Disposal (EOD) Day | United States | Observance |
| Sat, May 5 | Liberation Day | Netherlands | Multiple Types |
| Sat, May 5 | Senior Citizens Day | Palau | Public Holiday |
| Sat, May 5 | Arrival Day | Guyana | Public Holiday |
| Sat, May 5 | Freedom Day | Ethiopia | Public Holiday |
| Sat, May 5 | Children's Day | Multiple Countries | National Holiday |
| Sat, May 5 | World Naked Gardening Day | Multiple Countries | Unofficial |
| Sun, May 6 | National Nurses Day | United States | Observance |
| Sun, May 6 | Mother's Day | Romania | Observance |
| Sun, May 6 | Day of Gorans | Kosovo | Observance |
| Sun, May 6 | Mothers' Day | Multiple Countries | Observance |
| Sun, May 6 | Martyr's Day | Lebanon | Observance |
| Sun, May 6 | St. George's Day | Bulgaria | National Holiday |
| Sun, May 6 | Martyrs' Day | Syria | Public Holiday |
| Sun, May 6 | International No Diet Day | Multiple Countries | Unofficial |
| Mon, May 7 | Labour Day | Multiple Countries | Public Holiday |
| Mon, May 7 | May Day | Multiple Countries | Multiple Types |
| Mon, May 7 | Soldiers' Day | El Salvador | Observance |
| Mon, May 7 | Defender of the Fatherland Day | Kazakhstan | Public Holiday |
| Mon, May 7 | Early May Bank Holiday | United Kingdom | Bank Holiday |
| Tue, May 8 | Victory Day | Multiple Countries | Public Holiday |
| Tue, May 8 | Victory in Europe Day | Multiple Countries | Multiple Types |
| Tue, May 8 | WWII Victory Day | Multiple Countries | Multiple Types |
| Tue, May 8 | End of World War II | Slovakia | National Holiday |
| Tue, May 8 | Truman Day | United States (Missouri) | State Holiday |
| Tue, May 8 | Primary Election Day West Virginia | United States (West Virginia) | State Holiday |
| Tue, May 8 | End of the Second World War | Multiple Countries | Multiple Types |
| Tue, May 8 | World Ovarian Cancer Day | Multiple Countries | International |
| Tue, May 8 | Commemoration National Heroes WWII | Turkmenistan | Public Holiday |
| Tue, May 8 | Congress | Armenia | Observance |
| Tue, May 8 | Matsu's Birthday | Taiwan | Observance |
| Tue, May 8 | Parents' Day | South Korea | Observance |
| Tue, May 8 | Time of Remembrance and Reconciliation for Those Who Lost Their Lives during the Second World War | Multiple Countries | International |
| Tue, May 8 | Day of liberation | Norway | Observance, Flag Day |
| Tue, May 8 | Teacher's Day | Multiple Countries | Multiple Types |
| Wed, May 9 | Victory Day | Multiple Countries | Multiple Types |
| Wed, May 9 | Liberation Day | - (Guernsey, Jersey) | Multiple Types |
| Wed, May 9 | Victory Day / Memorial Day | Ukraine | National Holiday |
| Wed, May 9 | Victory and Peace Day | Armenia | National Holiday |
| Wed, May 9 | Remembrance Day | Uzbekistan | Public Holiday |
| Wed, May 9 | Europe Day | Kosovo | Official Holiday |
| Thu, May 10 | Ascension Day | Multiple Countries | Public Holiday |
| Thu, May 10 | Mother's Day | Multiple Countries | Observance |
| Thu, May 10 | State Holiday | United States (South Carolina) | Multiple Types |
| Thu, May 10 | Mothers' Day | Multiple Countries | Observance |
| Thu, May 10 | Constitution Day | Micronesia | Public Holiday |
| Sat, May 12 | St Andrew's Day | Georgia | Public Holiday |
| Sat, May 12 | World Migratory Bird Day | Multiple Countries | International |
| Sat, May 12 | Daylight Saving Time ends | Morocco | Clock Change/daylight Saving Time |
| Sat, May 12 | International Nurses Day | Multiple Countries | International |
| Sun, May 13 | Mother's Day | Multiple Countries | Observance |
| Sun, May 13 | Mothers' Day | Multiple Countries | Multiple Types |
| Sun, May 13 | Father's Day | Romania | Observance |
| Sun, May 13 | Mother´s Day | Cuba | Observance |
| Sun, May 13 | Day of the National Emblem and Flag of Belarus | Belarus | Observance |
| Sun, May 13 | Yom Yerushalayim (Jerusalem Day) | Israel | National Holiday, Hebrew |
| Mon, May 14 | Ascension Day | Multiple Countries | Public Holiday |
| Mon, May 14 | National Holiday | Paraguay | National Holiday |
| Mon, May 14 | National Unification Day | Liberia | Public Holiday |
| Mon, May 14 | Gospel Day | Tuvalu | Public Holiday |
| Mon, May 14 | Kamuzu Day | Malawi | Public Holiday |
| Tue, May 15 | Teacher's Day | Multiple Countries | Multiple Types |
| Tue, May 15 | Teacher´s Day | Colombia | Observance |
| Tue, May 15 | Independence Day | Paraguay | National Holiday |
| Tue, May 15 | Peace Officers Memorial Day | United States | Observance |
| Tue, May 15 | Family Day | Multiple Countries | Observance |
| Tue, May 15 | Feast Day of St Isidore | Spain (Madrid) | Local Holiday |
| Tue, May 15 | International Day of Families | Multiple Countries | International |
| Tue, May 15 | Europe Day | Moldova | Observance |
| Wed, May 16 | Ramadan begins | Multiple Countries | Multiple Types |
| Wed, May 16 | Ramadan starts | Multiple Countries | Multiple Types |
| Wed, May 16 | SPLA Day | South Sudan | Public Holiday |
| Wed, May 16 | General Prayer Day | Greenland | Public Holiday |
| Thu, May 17 | Orthodox Ascension Day | Romania | Observance, Orthodox |
| Thu, May 17 | Constitution Day | Nauru | Public Holiday |
| Thu, May 17 | Liberation Day | Congo Democratic Republic | Public Holiday |
| Thu, May 17 | Galicia Literature Day | Spain (Galicia) | Local Holiday |
| Thu, May 17 | World Information Society Day | Multiple Countries | International |
| Thu, May 17 | 17 May Constitution Day (1814) | Norway | National Holiday, Flag Day |
| Fri, May 18 | National Defense Transportation Day | United States | Observance |
| Fri, May 18 | International Museum Day | Singapore | Observance |
| Fri, May 18 | Day of Revival, Unity, and the Poetry of Magtymguly | Turkmenistan | Public Holiday |
| Fri, May 18 | Flag Day/University Day | Haiti | National/legal Holiday |
| Fri, May 18 | Bike to Work Day | Multiple Countries | Unofficial |
| Sat, May 19 | Commemoration of Atatürk, Youth and Sports Day | Turkey | National Holiday |
| Sat, May 19 | Armed Forces Day | United States | Observance |
| Sat, May 19 | Europe Day | Ukraine | Observance |
| Sat, May 19 | Pentecost Eve | Multiple Countries | Multiple Types |
| Sun, May 20 | Pentecost | Multiple Countries | Multiple Types |
| Sun, May 20 | Shavuot | Multiple Countries | Jewish Holiday |
| Sun, May 20 | Whitsunday | Multiple Countries | Multiple Types |
| Sun, May 20 | Whit Sunday | Multiple Countries | Observance |
| Sun, May 20 | Restoration of Independence Day | East Timor | Public Holiday |
| Sun, May 20 | World Autoimmune Arthritis Day | Multiple Countries | International |
| Sun, May 20 | Independence Day | Cuba | Observance |
| Sun, May 20 | Shavuot (Pentecost) | Israel | National Holiday, Hebrew |
| Sun, May 20 | Whit Sunday/Pentecost | Spain | Observance |
| Sun, May 20 | National Day | Cameroon | Public Holiday |
| Mon, May 21 | Whit Monday | Multiple Countries | Public Holiday |
| Mon, May 21 | Pentecost Monday | Switzerland (All Except Vs) | Common Local Holidays |
| Mon, May 21 | Discovery Day | Cayman Islands | Public Holiday |
| Mon, May 21 | Navy Day | Chile | National Holiday |
| Mon, May 21 | Battle of Las Piedras | Uruguay | Observance |
| Mon, May 21 | Saint Helena's Day | Saint Helena | Public Holiday |
| Mon, May 21 | World Day for Cultural Diversity for Dialogue and Development | Multiple Countries | International |
| Mon, May 21 | Victoria Day | Canada (All Except Ns , Nu , Qc) | Common Local Holidays |
| Mon, May 21 | National Patriots' Day | Canada (Quebec) | Local Holiday |
| Mon, May 21 | Independence Day | Montenegro | National Holiday |
| Tue, May 22 | Unity Day | Yemen | Public Holiday |
| Tue, May 22 | Buddha's Birthday | Multiple Countries | Multiple Types |
| Tue, May 22 | National Maritime Day | United States | Observance |
| Tue, May 22 | Harvey Milk Day | United States (California) | Local Observance |
| Tue, May 22 | International Day for Biological Diversity | Multiple Countries | International |
| Tue, May 22 | Independence Day (day 2) | Montenegro | National Holiday |
| Wed, May 23 | Labor Day / May Day | Jamaica | Public Holiday |
| Wed, May 23 | Constitution Day | Germany | Observance |
| Wed, May 23 | Emergency Medical Services for Children Day | United States | Observance |
| Wed, May 23 | International Day to End Obstetric Fistula | Multiple Countries | International |
| Wed, May 23 | Vlach’s National Day (for Vlach community) | Macedonia, Republic Of | Optional Holiday |
| Wed, May 23 | World Turtle Day | Multiple Countries | Unofficial |
| Thu, May 24 | Independence Day | Eritrea | Public Holiday |
| Thu, May 24 | The Battle of Pichincha | Ecuador | National Holiday |
| Thu, May 24 | Commonwealth Day | Belize | Public Holiday |
| Thu, May 24 | Bermuda Day | Bermuda | Public Holiday |
| Thu, May 24 | Culture and Literacy Day | Bulgaria | National Holiday |
| Thu, May 24 | Saints Cyril and Methodius' Day | Macedonia, Republic Of | National Holiday |
| Fri, May 25 | Independence Day | Jordan | National Holiday |
| Fri, May 25 | National Heroes Day | Turks And Caicos Islands | Public Holiday |
| Fri, May 25 | National Day/May 1810 Revolution | Argentina | National Holiday |
| Fri, May 25 | Africa Day | Multiple Countries | Public Holiday |
| Fri, May 25 | National Missing Children's Day | United States | Observance |
| Fri, May 25 | African Liberation Day | Multiple Countries | International |
| Fri, May 25 | Liberation and Resistance Day | Lebanon | Observance |
| Fri, May 25 | Africa Freedom Day | Zambia | Public Holiday |
| Fri, May 25 | African Union Day | Ghana | Public Holiday |
| Fri, May 25 | National Wine Day | Multiple Countries | Unofficial |
| Sat, May 26 | National Sorry Day | Australia | Observance |
| Sat, May 26 | Independence Day | Multiple Countries | Public Holiday |
| Sat, May 26 | Mother's Day | Poland | Observance |
| Sun, May 27 | Trinity Sunday | Multiple Countries | Christian |
| Sun, May 27 | Orthodox Pentecost | Multiple Countries | National Holiday, Orthodox |
| Sun, May 27 | Trinity | Czech Republic | Christian |
| Sun, May 27 | Mother's Day | Multiple Countries | Multiple Types |
| Sun, May 27 | Cultural Workers and Folk Artists Day | Ukraine | Observance |
| Sun, May 27 | Kiev Day | Ukraine | Observance |
| Sun, May 27 | Carpet Day | Turkmenistan | Observance |
| Sun, May 27 | Mother Day | Bolivia | Observance |
| Sun, May 27 | Children's Day | Nigeria | Observance |
| Sun, May 27 | Dniester Day | Moldova | Observance |
| Mon, May 28 | Hamburger Day | Multiple Countries | Unofficial |
| Mon, May 28 | Memorial Day | Multiple Countries | Multiple Types |
| Mon, May 28 | Spring Bank Holiday | Multiple Countries | Public Holiday |
| Mon, May 28 | Orthodox Pentecost Monday | Multiple Countries | National Holiday, Orthodox |
| Mon, May 28 | Jefferson Davis Birthday | United States (Mississippi) | Local Observance |
| Mon, May 28 | Holy Spirit Monday | Greece | Public Holiday |
| Mon, May 28 | Orthodox Pentecost holiday | Ukraine | National Holiday, Orthodox |
| Mon, May 28 | Republic Day | Multiple Countries | Multiple Types |
| Mon, May 28 | Derg Downfall Day | Ethiopia | Public Holiday |
| Tue, May 29 | International Day of United Nations Peacekeepers | Multiple Countries | International |
| Tue, May 29 | Day of Vesak | Multiple Countries | International |
| Tue, May 29 | Democracy Day | Nigeria | Public Holiday |
| Wed, May 30 | Harvest Festival | Malaysia | Common Local Holidays |
| Wed, May 30 | Mothers' Day | Nicaragua | Observance |
| Wed, May 30 | Indian Arrival Day | Trinidad And Tobago | Public Holiday |
| Wed, May 30 | Day of the Canary Islands | Spain (Canary Islands) | Local Holiday |
| Wed, May 30 | Anguilla Day | Anguilla | Public Holiday |
| Thu, May 31 | Corpus Christi | Multiple Countries | Multiple Types |
| Thu, May 31 | Harvest Festival Day 2 | Malaysia | Common Local Holidays |
| Thu, May 31 | Royal Brunei Armed Forces Day | Brunei | Public Holiday |
| Thu, May 31 | Canaries day observed | Spain (Canary Islands) | Local Holiday |
| Thu, May 31 | Day of Castile-La Mancha | Spain (Castile-la Mancha) | Local Holiday |
| Thu, May 31 | World No Tobacco Day | Multiple Countries | International |
