| Algonquin Township | |
| Settlement Type: | Township |
| Coordinates: | 42.1967°N -88.2781°W |
| Subdivision Type: | Country |
| Subdivision Name: |  United States |
| Subdivision Type1: | State |
| Subdivision Type2: | County |
| Subdivision Name2: | McHenry |
| Subdivision Type3: | Township |
| Subdivision Name3: | Algonquin |
| Established Title: | Established |
| Established Date: | November 6, 1849 |
| Leader Title: | Supervisor |
| Leader Name: | Randy Funk |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 48.03 |
| Area Land Sq Mi: | 46.42 |
| Area Water Sq Mi: | 1.61 |
| Area Water Percent: | 3.35 |
| Elevation Ft: | 902 |
| Population As Of: | 2020 |
| Population Density Sq Mi: | 1904.2 |
| Population Total: | 87633 |
| Timezone1: | CST |
| Utc Offset1: | -6 |
| Timezone1 Dst: | CDT |
| Utc Offset1 Dst: | -5 |
| Area Code Type: | Area codes |
| Area Code: | 815, 779, 847, 224 |
| Website: | www.algonquintownship.com |
| Pop Est Footnotes: | [1] |
| Blank Name: | FIPS code |
| Blank Info: | 17-111-00698 |
Algonquin Township is located in McHenry County, Illinois, with the township office in the city of Crystal Lake. As of the 2020 census, its population was 87,633 and it contained 33,960 housing units. It is the largest township by population in McHenry County.
According to the 2010 census, the township has a total area of, of which (or 96.65%) is land and (or 3.35%) is water.[2]