240
Battery → specs
Pick any battery — its dimensions, voltage, capacity, and uses appear below.
REFERENCE TABLE · EVERYDAY
Battery Sizes Chart
Every common battery size in one chart — AAA, AA, C, D, 9V, CR2032, CR123A, CR2, 23A, 18650, and LR44 — with exact millimeter dimensions, nominal voltages, typical mAh ranges, chemistries, and what each one actually powers. Three live lookups below: battery → full specs, voltage → which batteries, and a which-is-bigger size comparison. If you only remember one rule, make it this: size tells you the fit, voltage tells you the compatibility — you need both to match.
241
Voltage → which batteries
Pick a voltage — every common battery at that voltage appears below.
242
Which battery is bigger?
Pick two sizes — the size comparison, with real volumes, appears below.
The full chart: 11 common sizes
Read across: the battery, its shape, its dimensions in millimeters, nominal voltage, typical capacity, the chemistries it comes in, and what it usually powers. Dimensions are IEC maximums — a real cell from the drawer will be at or slightly under these numbers:
| Battery | Shape | Dimensions (mm) | Voltage | Typical capacity* | Common chemistries | Typical uses |
|---|---|---|---|---|---|---|
| AAA | Cylinder | 44.5 × 10.5 | 1.5 V | 1,000–1,200 mAh | Alkaline (LR03) · NiMH 1.2 V rechargeable · lithium 1.5 V | TV remotes, wireless mice & keyboards, thermometers, small toys |
| AA | Cylinder | 50.5 × 14.5 | 1.5 V | 1,700–3,000 mAh | Alkaline (LR6) · NiMH 1.2 V rechargeable · lithium 1.5 V | Game controllers, flashlights, toys, wall clocks, remotes |
| C | Cylinder | 50.0 × 26.2 | 1.5 V | 6,000–8,000 mAh | Alkaline (LR14) · NiMH 1.2 V rechargeable | Large flashlights, portable radios, big toys, boomboxes |
| D | Cylinder | 61.5 × 34.2 | 1.5 V | 8,000–12,000 mAh | Alkaline (LR20) · NiMH 1.2 V rechargeable | Lanterns, boomboxes, high-drain flashlights, portable stereos |
| 9V | Box | 48.5 × 26.5 × 17.5 | 9 V | 400–600 mAh | Alkaline (6LR61) · NiMH rechargeable · lithium primary | Smoke & CO detectors, multimeters, guitar pedals, microphones |
| CR2032 | Coin | 20.0 × 3.2 | 3.0 V | ~225 mAh | Lithium manganese dioxide (primary, not rechargeable) | Motherboard RTC, car key fobs, watches, digital scales |
| CR123A | Cylinder | 34.5 × 17.0 | 3.0 V | ~1,500 mAh | Lithium manganese dioxide (primary, not rechargeable) | Camera flashes, tactical flashlights, home security sensors |
| CR2 | Cylinder | 27.0 × 15.6 | 3.0 V | ~850 mAh | Lithium manganese dioxide (primary, not rechargeable) | Film-era cameras, motion sensors, medical devices |
| 23A / A23 | Cylinder | 28.5 × 10.3 | 12 V | ~55 mAh | Alkaline: eight LR932 cells in series (8LR932) | Key fobs, garage door openers, RF remotes, wireless doorbells |
| 18650 | Cylinder | 65.0 × 18.0 | 3.7 V | 2,500–3,500 mAh | Lithium-ion rechargeable (NMC/NCA/LFP) | Laptop packs, power banks, vapes, high-performance flashlights, power tools |
| LR44 / 357 | Button | 11.6 × 5.4 | 1.5 V | 110–160 mAh | Alkaline (LR44) · silver-oxide 1.55 V (357/SR44) | Calculators, laser pointers, thermometers, toys, watches |
*Capacity varies by brand, drain rate, temperature, and chemistry — these are typical ranges, not label claims. Alkaline makers don’t print mAh on the package precisely because of this. The 18650 range depends on the exact cell model; anything sold as an 18650 claiming over ~3,600 mAh is mislabeled.
The names are the dimensions: how to decode a battery code
Many battery names are measurements in disguise. CR2032 decodes exactly: CR = lithium manganese dioxide chemistry, 20 = 20 mm diameter, 32 = 3.2 mm thick. Same trick for 18650: 18 = 18 mm diameter, 650 = 65.0 mm long — and its AA-sized lithium cousin is called 14500 for the same reason (14 mm × 50 mm). LR44 is the older letter code: L = alkaline, R = round. The 23A’s real name is 8LR932: it is literally eight LR932 button cells stacked in series inside one wrapper — eight × 1.5 V = 12 V — which is why a 12-volt battery only holds about 55 mAh. And 6LR61, the code behind the “9V”, counts the six 1.5 V cells inside: that’s why a 9V is called a battery (a pack of cells) while an AA is technically a single cell.
Worked example: the TV remote takes AAA. From the chart, a AAA is 44.5 mm long × 10.5 mm diameter, 1.5 V, about 1,000–1,200 mAh alkaline. An AA is 50.5 × 14.5 mm — 6 mm longer and 4 mm thicker — so an AA will not fit an AAA slot, and a AAA rattles loose in an AA slot without reliably touching the contacts: size must match exactly. By volume the AA is about 2.2× the AAA — which is roughly why it stores 2–3× the energy. Either battery type fits the remote only if the slot was made for it; when in doubt, read the diagram printed inside the battery door.
Output · formula · meaning: how to read the chart
| Output | Formula | What it means |
|---|---|---|
| Dimensions (mm) | cylinder: length × diameter · 9V: H × W × T | AA = 50.5 long × 14.5 wide; 9V = 48.5 × 26.5 × 17.5. |
| Typical capacity | mAh ÷ load (mA) ≈ hours of runtime | A 2,000 mAh AA feeding a 50 mA remote runs about 40 hours — rough guide only. |
| Coin-cell name code | diameter (mm) + thickness (tenths of mm) | CR2032 = 20 mm × 3.2 mm. CR = 3 V lithium. |
| Cylindrical name code | diameter (mm) + length (mm) | 18650 = 18 mm × 65 mm rechargeable lithium-ion. |
| Series voltage | cells in series × cell voltage | Four AA alkalines in a row = 4 × 1.5 V = 6 V. |
Who uses this
- Parents: the remote ate its batteries again — look up whether it’s AAA or AA before leaving for the store, and learn why the 9V in the smoke detector is a different animal entirely.
- Photographers and flashlight owners: CR123A vs 18650 vs AA — which one a light actually takes, what voltage it expects, and why stuffing a 3.7 V cell into a 1.5 V light is a bad idea.
- Key-fob and garage-door owners: finding the tiny 23A/A23 or CR2032 the fob eats, and learning the 23A is really eight button cells pretending to be one battery.
- Students and tinkerers: matching calculator, toy, and thermometer cells — LR44 vs 357 (same size, different chemistry), and why stacking two LR44s never replaces a CR2032.
Accuracy & limitations
Dimensions are IEC maximums — real cells run at or slightly under them, and brand tolerances vary (the CR123A runs about 33.4–34.5 mm tall by manufacturer). Protected 18650s (with built-in protection circuits) are several millimeters longer than the bare 65 mm and may not fit tight flashlights. Capacities are typical ranges, not guarantees: they shift with brand, drain rate, temperature, and age, which is why alkaline makers don’t print mAh on the label. Rechargeable NiMH AA/AAA cells are 1.2 V, not 1.5 V — fine in most low-drain devices, occasionally fussy in voltage-sensitive ones. This page is a reference — always match both the physical size and the voltage printed in the device’s battery compartment, and never mix chemistries in one device.
Cite this reference chartBright Side Kit. “Battery Sizes Chart.” brightoolbox.com, 2026.
Bright Side Kit. "Battery Sizes Chart." https://brightoolbox.com/battery-sizes-chart/ Accessed October 22, 2026.Frequently asked questions
Can I use rechargeable 1.2V NiMH batteries instead of 1.5V alkaline?
Usually yes for low-drain devices — TV remotes, wall clocks, thermometers, and mice run happily on 1.2 V NiMH cells, and rechargeables save real money in things you power often (game controllers, toys). Some voltage-sensitive devices (certain cameras, sensors, flash units) expect the full 1.5 V and report “low battery” early on 1.2 V cells — those are the cases to keep alkalines for. Either way, never mix rechargeable and alkaline cells in the same device: their voltages and discharge curves differ, and the weaker one can leak or reverse.
Why is a 9V called a "battery" but an AA is a "cell"?
Because it’s literally true: the 9V’s IEC code is 6LR61, and the 6 counts the six 1.5 V cells stacked in series inside the wrapper. A “battery” is technically a pack of cells; an AA or AAA is a single cell, so engineers call them cells and the language leaked. The 23A is the same idea taken further — eight button cells in one wrapper to make 12 V. (This page calls everything “batteries” anyway, because that’s what everyone says at the store.)
Do coin cells expire?
Lithium coin cells like the CR2032 last up to about 10 years in storage — their self-discharge is under 1% a year, which is why the spare in the junk drawer usually still works. Alkaline button cells (LR44) fade faster, and once a cell is in a device it drains with use regardless of the date. Store spares cool and dry, and keep button cells away from small children — swallowed cells are an emergency; child-resistant battery compartments are the standard for a reason.
Can I use an 18650 in an AA flashlight?
No — different size, different voltage. An 18650 is 18 × 65 mm and 3.7 V; an AA is 14.5 × 50.5 mm and 1.5 V — it won’t fit, and the higher voltage can fry a light built for alkalines. The lookalike you’re thinking of is the 14500: literally AA-size lithium-ion (14 × 50 mm) — but it’s still 3.7 V, so only use one if the flashlight’s manual explicitly allows it. When a light says “takes 18650,” it needs exactly that size and voltage.
Can I stack two LR44s instead of a CR2032?
No — they’re completely different sizes. An LR44 is 11.6 × 5.4 mm; a CR2032 is 20 × 3.2 mm: wider, thinner, and a different holder entirely. Two LR44s also add up to 3 V, which tempts people, but a CR2032 holder physically cannot close on stacked LR44s and the contact geometry is wrong. Match the code on the old battery, not the voltage math — LR44, 357/SR44, and AG13 are the same size (interchangeable); CR2032 is its own world.
My smoke detector chirps even with a new 9V battery — why?
Three usual suspects: (1) the battery isn’t seated right or the compartment door isn’t fully closed — reseat it and make sure it latches; (2) you used the wrong type — most detectors want alkaline, not rechargeable, whose voltage profile can read “low” to the detector; (3) the detector kept the old error — pull the battery, hold the test button 15–20 seconds to drain the residual charge, then reinstall. If it still chirps, check the manufacture date: detectors expire after 8–10 years and chirp on purpose at end of life — no new battery fixes that; replace the unit.