26650
Cylindrical Cells · 3 specs
Direct Answer
A 26650 Li-ion cell measures 26mm in diameter and 65mm in length, used in high-drain devices like flashlights, power tools, and RC-hobby battery packs. The format is produced in multiple chemistries with different nominal voltages, so '26650' alone does not guarantee a specific voltage.
Source: IEC 61960 · Last reviewed Aug 28, 2026
Specs
| Diameter | 26.00 mm |
| Overall Length | 65.00 mm |
| Chemistry | Lithium-ion (Li-ion or LiFePO4, varies by product) |
One Size, More Than One Chemistry
Unlike most cylindrical lithium cell formats, '26650' describes only the physical envelope -- 26mm diameter, 65mm length -- not a single fixed chemistry or voltage. Most 26650 cells are conventional lithium-ion (nominally around 3.6-3.7V), built for either high energy density or high discharge current depending on the product line, but the same physical size is also widely used for lithium iron phosphate (LiFePO4) cells, which are nominally 3.2V. A buyer matching a replacement cell by size alone can easily end up with the wrong voltage for their device.
The 26650's larger volume compared to an 18650 or 21700 makes it popular in applications that value raw capacity or discharge current over compactness: high-powered flashlights, radio-control hobby battery packs, and some power tools. As with other high-capacity lithium cylindrical formats, advertised capacity figures for 26650 cells vary widely between manufacturers and are frequently inflated beyond what the cell's physical volume can realistically hold, so treat any single advertised mAh figure with caution.