# item.guide
Side-by-Side Comparison Cylindrical Cells

21700 vs. 26650

Comparing 2 standards across 4 specifications. 4 key differences identified.

Comparing:
21700
26650
21700 →

A 21700 Li-ion cell measures 21.1mm in diameter and 70.4mm in length. Offering 4000 to 5000 mAh capacity at 3.6V nominal, it provides up to 50% more energy density than an 18650 cell.

View full 21700 spec sheet →
26650 →

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.

View full 26650 spec sheet →

Specification Comparison Table

4 Parameters
Parameter / Spec
21700
26650
Diameter
21.10 mm 26.00 mm
Overall Length
70.40 mm 65.00 mm
Nominal Capacity
4000–5000 mAh —
Chemistry
— Lithium-ion (Li-ion or LiFePO4, varies by product)

Other Alternatives to Compare

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