The UN announces the ranking on March 20 every year to mark the International Day of Happiness.
Thailand’s household happiness was reported in the 2012 survey at 7.17 from a possible total of 9 points.
The northeastern province of Yasothorn is champion among Thai provinces nationwide, receiving 8.35 points, followed by Surin, Trang, Nakhon Phanom and Pathum Thani.
People in the seaboard province of Samut Songkram are least happy.
Permanent Secretary for Public Health Narong Sahamethapat said the ranking was aimed at encouraging countries to concentrate on the people’s happiness and sustainable quality of life in their economic development.
According to the survey among 156 countries worldwide in 2010-2012, Denmark ranked first while Thailand was 36th worldwide and second in Southeast Asia after Singapore which ranked 30th.
Elements contributing to happiness include income, employment, good relationships and trusting people in a community, values inclined to happiness and religion, physical and mental health, family relationship, education, and equality among men and women and social status.
A joint survey by the National Statistics Office and the Mental Health Department in 2012 found Thailand's happiness level at 7.17 from 9 points among Thai people aged above 15, and family was the most significant factor contributing to happiness.
Ten provinces with the highest level of happiness were Yasothorn, 8.35 points, Surin, 8.03 points, Trang, 7.83 points, Nakhon Phanom, 7.96 points, Pathum Thani, 7.85 points, Yala, 7.83 points, Petchabun, 7.77 points, Nan, 7.77 points, Pichit, 7.75 points, and Chaiyaphum, 7.75 points.
Three provinces where people were least happy were Samut Songkram, 5.39 points, Pattani, 6.06 points and Sa Kaeo, 6.10 points.
Dr Narong said factors contributing to happiness among Thai people were family gatherings, good health, regular exercise, belief in religious teachings and meditation, sufficient income, stable jobs, being free of debt, and possessing land for farming.