AAA battery

An AAA battery measures 1.75 inches (44.5 mm) long and 0.41 inches (10.5 mm) in diameter. It is a smaller, lighter alternative to AA batteries, commonly used in compact electronics where space is limited. This page covers the exact dimensions, weight, and how AAA compares to other common battery sizes.

Dimensions

Weight

An alkaline AAA battery weighs approximately 0.4 ounces (11.5 grams), roughly half the weight of an AA battery, reflecting its smaller size and lower material content.

Battery size comparison

AAA is about 5.5 mm shorter and 4 mm narrower than AA, making it noticeably more compact. This size difference means AAA cannot be substituted for AA in most devices without a specific adapter sleeve, since the smaller diameter fails to make proper contact with AA-sized battery terminals.

Voltage and capacity

A standard alkaline AAA battery provides 1.5 volts, the same as AA, C, and D batteries, since voltage comes from the battery chemistry rather than its physical dimensions. Capacity is where AAA falls short compared to larger sizes, typically holding 500 to 1,200 mAh compared to AA’s 1,800 to 2,700 mAh, meaning AAA batteries generally need replacing or recharging more often in equivalent devices.

Common devices using AAA batteries

AAA batteries are the standard choice for compact devices like small remote controls, wireless computer mice, digital thermometers, and some hearing aids and medical devices. Their smaller size makes them the preferred option whenever device manufacturers need to minimize battery compartment space.

Frequently asked questions

What is the exact size of an AAA battery?

1.75 inches (44.5 mm) long and 0.41 inches (10.5 mm) in diameter, the standard size defined by the IEC.

Can I use AA batteries instead of AAA?

No, not directly. AA batteries are longer and thicker than AAA, so they will not fit in a battery compartment sized for AAA cells without a specific adapter.

How much does an AAA battery weigh?

About 11.5 grams (0.4 ounces) for alkaline versions, roughly half the weight of a standard AA battery.

What voltage does an AAA battery provide?

1.5 volts, the same as AA, C, and D batteries, since voltage depends on the internal chemistry rather than the physical size of the battery.

Why do AAA batteries run out faster than AA?

AAA batteries have less internal capacity due to their smaller size, typically 500 to 1,200 mAh compared to AA’s 1,800 to 2,700 mAh, so they store and deliver less total energy before needing replacement.

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