| Călmățuiul Sec | |
| Pushpin Map: | Romania |
| Subdivision Type1: | Country |
| Subdivision Name1: | Romania |
| Subdivision Type2: | Counties |
| Subdivision Name2: | Olt, Teleorman |
| Subdivision Type3: | Villages |
| Subdivision Name3: | Mihăești, Călmățuiu de Sus |
| Length: | 48km (30miles) |
| Mouth: | Călmățui |
| Mouth Coordinates: | 44.0132°N 24.8089°W |
| Progression: | Călmățui→ |
| Basin Size: | 167km2 |
| Custom Label: | River code |
| Custom Data: | XIV.1.31.2 |
The Călmățuiul Sec is a left tributary of the river Călmățui in Romania. It flows into the Călmățui in Balta Sărată.[1] Its length is 48km (30miles) and its basin size is 167km2.