Uttwil is a municipality in the district of Arbon in the canton of Thurgau in Switzerland.
Uttwil has an area, , of . Of this area, or 52.8% is used for agricultural purposes, while or 30.6% is forested. Of the rest of the land, or 16.1% is settled (buildings or roads), or 0.9% is either rivers or lakes and or 0.2% is unproductive land.
Of the built up area, industrial buildings made up 8.3% of the total area while housing and buildings made up 0.7% and transportation infrastructure made up 0.7%. Power and water infrastructure as well as other special developed areas made up 2.5% of the area while parks, green belts and sports fields made up 3.9%. Out of the forested land, 29.0% of the total land area is heavily forested and 1.6% is covered with orchards or small clusters of trees. Of the agricultural land, 36.2% is used for growing crops, while 16.6% is used for orchards or vine crops. All the water in the municipality is in lakes.
Uttwil has a population () of . , 13.9% of the population are foreign nationals. Over the last 10 years (1997–2007) the population has changed at a rate of 18.7%. Most of the population () speaks German (94.2%), with Italian being second most common ( 2.0%) and Albanian being third ( 1.0%).
the gender distribution of the population was 50.9% male and 49.1% female. The population was made up of 710 Swiss men (43.0% of the population), and 130 (7.9%) non-Swiss men. There were 712 Swiss women (43.1%), and 99 (6.0%) non-Swiss women.
In there were 20 live births to Swiss citizens and 2 births to non-Swiss citizens, and in same time span there were 11 deaths of Swiss citizens and 2 non-Swiss citizen deaths. Ignoring immigration and emigration, the population of Swiss citizens increased by 9 while the foreign population remained the same. There were 2 Swiss men who emigrated from Switzerland to another country, 6 Swiss women who emigrated from Switzerland to another country, 10 non-Swiss men who emigrated from Switzerland to another country and 7 non-Swiss women who emigrated from Switzerland to another country.