The population of Grenola is 216 people, with 92 households and 64 families. There are 128 housing units, giving the population density of 466.7 people per square mile. The city has a high proportion of White people, with 97.7% being White, 1.9% Asian, and 0.5% of people of two races. There are several schools in the area, including Grenola High School.
The Grenola Baptist Church was part of the Disciples of Christ organization until 1950. The church reported on its membership every year to the denomination's headquarters in Topeka. In 1908, there were 137 members, and in 1918, a high was 96. In 1924, the congregation grew to 229, with pastor Enos O. Wonder. There were 62 additions to the church, and in 1950, it had 130 members. After World War II, the church's membership fell to 130. In 1954, the church sold its parsonage to student pastors.
The first digit of the Grenola city ZIP code designates the country area, which ranges from zero for the Northeast to nine for the far West. The second and third digits indicate the sectional center facility, and the last two digits are the city's postal code. A Grenola city map shows where the town is located. The map is a reference, and is not intended for detailed navigation.