Batteries come in different sizes so they can fit different devices and provide different amounts of energy. The letters—such as AA or C—tell you the battery’s size and type.
Common battery sizes
- AAA: Small and thin. Often used in TV remotes and small toys.
- AA: Bigger than AAA. Common in toys, clocks, and wireless devices.
- C: Wider and larger than AA. Often used in bigger toys and some flashlights.
- D: The largest of these four. Often used in large flashlights and devices that need to run for a long time.
For these common batteries, a larger size can usually hold more energy, so it may power a device for longer. But the actual amount of energy depends on the battery’s brand and whether it is alkaline, rechargeable, or another kind.
Do bigger batteries have more voltage?
Not necessarily! Many regular AA, AAA, C, and D batteries provide about 1.5 volts, even though they are different sizes. Rechargeable versions are often rated around 1.2 volts.
Other battery types
9-volt batteries are usually rectangular and are used in things like smoke alarms. Small, flat coin batteries power devices such as watches and some toys. These are different shapes and may have different voltages.
How to choose the right one
- Check the label or instructions on the device.
- Use the exact battery size it asks for.
- Never force a battery into a space where it does not fit.
- Ask an adult for help replacing batteries, and do not mix old and new batteries.
Remember: Battery size tells you how big it is, but the device’s instructions tell you which one to use.