| Official Name: | Klahr, Pennsylvania |
| Settlement Type: | Census-designated place |
| Pushpin Map: | Pennsylvania#USA |
| Pushpin Label: | Klahr |
| Pushpin Label Position: | top |
| Coordinates: | 40.2978°N -78.5125°W |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Pennsylvania |
| Subdivision Type2: | County |
| Subdivision Name2: | Blair |
| Subdivision Type3: | Township |
| Subdivision Name3: | Greenfield |
| Unit Pref: | Imperial |
| Area Footnotes: | [1] |
| Area Total Sq Mi: | 0.14 |
| Area Land Sq Mi: | 0.14 |
| Area Water Sq Mi: | 0.00 |
| Area Total Km2: | 0.35 |
| Area Land Km2: | 0.35 |
| Area Water Km2: | 0.00 |
| Population As Of: | 2020 |
| Population Footnotes: | [2] |
| Population Total: | 76 |
| Population Density Sq Mi: | 562.96 |
| Population Density Km2: | 217.00 |
| Timezone: | Eastern (EST) |
| Utc Offset: | -5 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | -4 |
| Elevation Ft: | 1624 |
| Postal Code Type: | ZIP Code |
| Postal Code: | 16625 (Claysburg) |
| Area Code: | 814/582 |
| Blank Name: | FIPS code |
| Blank Info: | 42-40072 |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 2805516 |
Klahr is an unincorporated community and census-designated place (CDP) in Blair County, Pennsylvania, United States. It was first listed as a CDP prior to the 2020 census.
The CDP is in southwestern Blair County, in the southern part of Greenfield Township. It sits at the head of the valley of Smoky Run, at the base of Spruce Knob, an eastern spur of Blue Knob, the second-highest summit in Pennsylvania. Smoky Run is a southeastward-flowing tributary of Beaverdam Creek, one of the main headwater tributaries of the Frankstown Branch of the Juniata River, part of the Susquehanna River watershed.
Locust Hollow Road is the main street through Klahr, leading north 2miles to Ski Gap and southeast to Cotton Town. Claysburg is 5miles by road to the east, and Hollidaysburg is to the northeast.