Alkaline battery sizes reference
All standard alkaline dry-cell batteries produce 1.5 V nominal (fresh off the shelf). Capacity varies significantly with size. The 9V (PP3) battery is six 1.5 V cells in series inside one case.
Cylindrical alkaline batteries
| Common name | IEC designation | ANSI designation | Diameter | Height | Voltage | Typical capacity | Common devices |
|---|---|---|---|---|---|---|---|
| AAA | LR03 | ANSI 24A | 10.5 mm | 44.5 mm | 1.5 V | 1,000–1,200 mAh | TV remotes, slim flashlights, small electronics, hearing aid chargers |
| AA | LR6 | ANSI 15A | 14.5 mm | 50.5 mm | 1.5 V | 2,500–3,000 mAh | Toys, flashlights, remote controls, game controllers, clocks |
| C | LR14 | ANSI 14A | 26.2 mm | 50.0 mm | 1.5 V | 7,500–8,000 mAh | Portable radios, lanterns, larger toys, musical instruments |
| D | LR20 | ANSI 13A | 34.2 mm | 61.5 mm | 1.5 V | 12,000–18,000 mAh | Camping lanterns, large flashlights, boom boxes, some power tools |
Rectangular batteries
| Common name | IEC designation | ANSI designation | Dimensions (L × W × H) | Voltage | Typical capacity | Common devices |
|---|---|---|---|---|---|---|
| 9V (PP3) | 6LR61 | ANSI 1604A | 48.5 × 26.5 × 17.5 mm | 9 V | 550–600 mAh | Smoke detectors, multimeters, guitar effects, carbon monoxide detectors |
Coin cell batteries
Coin cells use a two-part designation: the prefix indicates chemistry (CR = lithium manganese dioxide, LR = alkaline, SR = silver oxide), and the numbers encode the diameter and height in millimeters.
| Designation | Chemistry | Diameter | Height | Voltage | Typical capacity | Common devices |
|---|---|---|---|---|---|---|
| CR2032 | Lithium | 20 mm | 3.2 mm | 3 V | 220–240 mAh | Motherboard CMOS battery, key fobs, watches, glucose meters |
| CR2025 | Lithium | 20 mm | 2.5 mm | 3 V | 155–170 mAh | Key fobs, calculators, slim watches |
| CR2016 | Lithium | 20 mm | 1.6 mm | 3 V | 75–90 mAh | Key fobs (stacked pairs), thin remotes, fitness trackers |
| CR1616 | Lithium | 16 mm | 1.6 mm | 3 V | 55–60 mAh | Key fobs (Toyota/Lexus), small remotes |
| CR1632 | Lithium | 16 mm | 3.2 mm | 3 V | 120–140 mAh | Key fobs, medical devices |
| LR44 | Alkaline | 11.6 mm | 5.4 mm | 1.5 V | 110–150 mAh | Calculators, laser pointers, toys, small electronics |
| SR44 (equivalent) | Silver oxide | 11.6 mm | 5.4 mm | 1.55 V | 150–200 mAh | Watches, precision instruments (slightly higher voltage and capacity) |
Coin cell safety: Coin cells are a major choking and swallowing hazard for children. A CR2032 swallowed by a child can cause severe burns from electrolysis within 2 hours. Keep all coin cells out of reach of children and use screw-locked battery compartments where possible.
Can you substitute one size for another?
| Situation | Can substitute? | Notes |
|---|---|---|
| AA in a C or D holder (with adapter sleeve) | Yes, temporarily | Voltage is the same; capacity is much lower. Device will run for a shorter time. |
| AAA in an AA holder (with spacer) | Yes, temporarily | Same voltage; AAA has ~⅓ the capacity of AA. |
| CR2025 instead of CR2032 | Sometimes | Same diameter and voltage; CR2025 is 0.7 mm thinner. May fit loosely or not make contact. Lower capacity. |
| LR44 instead of SR44 | For most devices, yes | LR44 is 1.5 V vs SR44's 1.55 V. In precision devices (watches with quartz movement) use SR44 for accuracy. |
| AA instead of 9V | No | Different voltage (1.5 V vs 9 V) and connector. Not interchangeable. |