| Official Name: | Chehel Sar |
| Native Name: | چهل سر |
| Settlement Type: | village |
| Pushpin Map: | Iran |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | Razavi Khorasan |
| Subdivision Type2: | County |
| Subdivision Name2: | Mahvelat |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Shadmehr |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Mahvelat-e Shomali |
| Population As Of: | 2006 |
| Population Total: | 172 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
| Coordinates: | 35.0372°N 58.8919°W |
Chehel Sar (Persian: چهل سر) is a village in Mahvelat-e Shomali Rural District, Shadmehr District, Mahvelat County, Razavi Khorasan Province, Iran. At the 2006 census, its population was 172, in 47 families.