Adrian White, from the UK's University of Leicester, used the responses of 80,000 people worldwide to map out subjective wellbeing.
Denmark came top, followed closely by Switzerland and Austria. The UK ranked 41st. Zimbabwe and Burundi came bottom.
A nation's level of happiness was most closely associated with health levels.
Prosperity and education were the next strongest determinants of national happiness.
1st - Denmark, 2nd - Switzerland, 3rd - Austria, 4th - Iceland, 5th - The Bahamas, 10th - Canada, 23rd - USA, 41st - UK, 90th - Japan, 96th - Iran, 178th - Burundi (last)