Grossaffoltern has a population (as of December 2018) of 3,018.
 As of 2010, 4.6% of the population are resident foreign nationals.
 Over the last 10 years (2000–2010) the population has changed at a rate of -0.2%.
 Migration accounted for 0.3%, while births and deaths accounted for 1.8%.

Most of the population (as of 2000) speaks German (2,700 or 96.4%) as their first language, French is the second most common (23 or 0.8%) and English is the third (16 or 0.6%).
 There are 12 people who speak Italian.

As of 2008, the population was 50.6% male and 49.4% female.
 The population was made up of 1,336 Swiss men (48.0% of the population) and 72 (2.6%) non-Swiss men.
 There were 1,317 Swiss women (47.3%) and 5 (0.2%) non-Swiss women.
 Of the population in the municipality, 846 or about 30.2% were born in Grossaffoltern and lived there in 2000.
 There were 1,283 or 45.8% who were born in the same canton, while 413 or 14.8% were born somewhere else in Switzerland, and 169 or 6.0% were born outside of Switzerland.

As of 2000, children and teenagers (0–19 years old) make up 25.5% of the population, while adults (20–64 years old) make up 60.7% and seniors (over 64 years old) make up 13.8%.

As of 2000, there were 1,135 people who were single and never married in the municipality.
 There were 1,421 married individuals, 136 widows or widowers and 108 individuals who are divorced.

As of 2000, there were 1,105 private households in the municipality, and an average of 2.5 persons per household.
 There were 256 households that consist of only one person and 79 households with five or more people.
 In 2000, a total of 1,075 apartments (91.9% of the total) were permanently occupied, while 63 apartments (5.4%) were seasonally occupied and 32 apartments (2.7%) were empty.
 As of 2009, the construction rate of new housing units was 1.8 new units per 1000 residents.
 The vacancy rate for the municipality, in 2010, was 2.27%.

The historical population is given in the following chart:
Grossaffoltern has a population (as of December 2018) of 3,018.  As of 2010, 4.6% of the population are resident foreign nationals.  Over the last 10 years (2000–2010) the population has changed at a rate of -0.2%.  Migration accounted for 0.3%, while births and deaths accounted for 1.8%.
Most of the population (as of 2000) speaks German (2,700 or 96.4%) as their first language, French is the second most common (23 or 0.8%) and English is the third (16 or 0.6%).  There are 12 people who speak Italian.
As of 2008, the population was 50.6% male and 49.4% female.  The population was made up of 1,336 Swiss men (48.0% of the population) and 72 (2.6%) non-Swiss men.  There were 1,317 Swiss women (47.3%) and 5 (0.2%) non-Swiss women.  Of the population in the municipality, 846 or about 30.2% were born in Grossaffoltern and lived there in 2000.  There were 1,283 or 45.8% who were born in the same canton, while 413 or 14.8% were born somewhere else in Switzerland, and 169 or 6.0% were born outside of Switzerland.
As of 2000, children and teenagers (0–19 years old) make up 25.5% of the population, while adults (20–64 years old) make up 60.7% and seniors (over 64 years old) make up 13.8%.
As of 2000, there were 1,135 people who were single and never married in the municipality.  There were 1,421 married individuals, 136 widows or widowers and 108 individuals who are divorced.
As of 2000, there were 1,105 private households in the municipality, and an average of 2.5 persons per household.  There were 256 households that consist of only one person and 79 households with five or more people.  In 2000, a total of 1,075 apartments (91.9% of the total) were permanently occupied, while 63 apartments (5.4%) were seasonally occupied and 32 apartments (2.7%) were empty.  As of 2009, the construction rate of new housing units was 1.8 new units per 1000 residents.  The vacancy rate for the municipality, in 2010, was 2.27%.
The historical population is given in the following chart:
Grossaffoltern