Sirnach is a municipality in the district of Münchwilen in the canton of Thurgau in Switzerland.

Sirnach has an area, as of 2009[update], of 12.41 square kilometers (4.79 sq mi).

Most of the population (as of 2000[update]) speaks German (85.5%), with Italian being second most common ( 4.7%) and Albanian being third ( 3.0%).

[6] The age distribution, as of 2009[update], in Sirnach is; 696 children or 10.0% of the population are between 0 and 9 years old and 956 teenagers or 13.8% are between 10 and 19.

In the federal election, a total of 1,860 votes were cast, and the voter turnout was 44.3%.

[13] The historical population is given in the following table:[14] As of  2007[update], Sirnach had an unemployment rate of 1.81%.

[7] From the 2000 census[update], 3,094 or 48.7% were Roman Catholic, while 1,794 or 28.2% belonged to the Swiss Reformed Church.

Of the children in kindergarten, 70 or 48.6% were female, 39 or 27.1% were not Swiss citizens and 33 or 22.9% did not speak German natively.

The lower and upper primary levels begin at about age 5-6 and last for 6 years.

At the lower primary level, there were 91 children or 44.4% of the total population who were female, 58 or 28.3% were not Swiss citizens and 63 or 30.7% did not speak German natively.

In the upper primary level, there were 131 or 49.2% who were female, 51 or 19.2% were not Swiss citizens and 61 or 22.9% did not speak German natively.

There were 117 teenagers who were in the advanced school, of which 67 or 57.3% were female, 15 or 12.8% were not Swiss citizens and 14 or 12.0% did not speak German natively.

There were 99 teenagers who were in the standard school, of which 40 or 40.4% were female, 38 or 38.4% were not Swiss citizens and 36 or 36.4% did not speak German natively.

Finally, there were 26 teenagers who were in special or remedial classes, of which 8 or 30.8% were female, 9 or 34.6% were not Swiss citizens and 12 or 46.2% did not speak German natively.