Batteries, sorted

What battery do I need?

Pick your device, type the code off the old battery, or measure it. We'll show the size, voltage, other names it's sold under, and how to swap it safely, with every number linked to the maker's datasheet.

Find my battery Battery size chart

Specs from maker datasheets
Every number sourced and dated
Free, no sign-up

Hands slide two fresh AA batteries into the back of a TV remote on a sunny living room coffee table, an open box of batteries and a mug beside it (AI-generated image)

The everyday six

Full size chart →

Maximum sizes from Energizer datasheets.^{[1 · Oct 29, 2026]}^{[2 · Oct 29, 2026]}^{[3 · Oct 29, 2026]}^{[4 · Oct 29, 2026]}^{[5 · Oct 29, 2026]}^{[6 · Oct 29, 2026]}

A woman reaches up to a white ceiling smoke alarm in a bright hallway, holding a fresh 9V battery (AI-generated image)

Smoke alarms

Chirping? Check the label first.

Alarms run on a 9V, AA batteries or a sealed 10-year battery. Change a replaceable battery at least once a year, and replace a sealed 10-year alarm when it chirps.^{[7 · Oct 29, 2026]}^{[8 · Oct 29, 2026]}

Smoke alarm battery guide

Hands open a car key fob on a kitchen counter with a small screwdriver, showing the coin cell inside, a new coin cell beside it (AI-generated image)

Coin cells

CR2032, CR2025 or CR2016?

Same 20 mm width, same 3 V. The last two digits are the thickness: 3.2, 2.5 or 1.6 mm. Buy the one printed on the old cell.^{[6 · Oct 29, 2026]}^{[9 · Oct 29, 2026]}^{[10 · Oct 29, 2026]}

Compare coin cells Key fob guide

In the garage

Car battery? Match the group size.

BCI group sizes set a battery's case size, terminal position and type.^{[11 · Oct 29, 2026]}^{[12 · Oct 29, 2026]} Check your current battery's label or owner's manual for yours.

SizeGroup number, e.g. 24F, 35, 48 (H6), 94R
Posts"R" means reversed terminals
CCACold cranking amps at 0°F
TypeFlooded, EFB or AGM

Group size chart

A man in a flannel shirt and work gloves lifts a car battery out of the engine bay of a silver car in a tidy home garage (AI-generated image)

Hands put clear tape over the end of a used battery next to a clear zip bag of old batteries ready for a recycling drop-off (AI-generated image)

Done with it?

Bag it or tape it, then drop it off.

Lithium, rechargeable, coin and car batteries don't belong in the trash. Bag each battery or tape its terminals and take it to a recycler.^{[13 · Oct 29, 2026]}^{[14 · Oct 29, 2026]}

Safety and recycling

Battery guides

Sources: 1. Energizer E91 AA alkaline datasheet (PDF). 2. Energizer E92 AAA alkaline datasheet (PDF). 3. Energizer E93 C alkaline datasheet (PDF). 4. Energizer E95 D alkaline datasheet (PDF). 5. Energizer 522 9V alkaline datasheet (PDF). 6. Energizer CR2032 lithium coin datasheet (PDF). 7. Kidde, What type of battery does my alarm use?. 8. NFPA, Changing clocks and batteries. 9. Energizer CR2025 lithium coin datasheet (PDF). 10. Energizer CR2016 lithium coin datasheet (PDF). 11. Battery Council International, BCI group sizes. 12. Interstate Batteries, Battery glossary. 13. US EPA, Used household batteries. 14. The Battery Network, What to recycle. Checked Oct 29, 2026. Inch conversions are our own arithmetic from the millimeter figures. Brand names and trademarks belong to their owners; specs are restated in our own words and tables, not reproduced.