Type B vs Type O Plugs: Differences & Compatibility

Type B vs Type O plugs are not compatible: an adapter is needed in both directions. Type B is a 3-pin, grounded plug rated 15A at 100-127V, while Type O is a 3-pin, grounded plug rated 16A at 220-240V. The two differ mainly in voltage, amperage and pin design, which is what decides compatibility — whether a Type B plug fits a Type O socket, and vice versa. Compare this with type K versus type O plug shape and socket design compared.

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Not Compatible Adapter needed in both directions Compatible Adapters	Type B	Type O
Standard	NEMA 5-15	TIS 166-2549
Pin Configuration	Two flat parallel pins plus round grounding pin (4.8mm diameter)	Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin)
Grounding	Grounded	Grounded
Pin Count	3	3
Amperage	15A	16A
Voltage Range	100-127V	220-240V

Key Differences Between Type B and Type O

Here's how Type B and Type O compare, point by point.

Grounding: Both Type B and Type O are grounded.
Pin Size and Shape: Type B: Two flat parallel pins plus round grounding pin (4.8mm diameter). Type O: Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin).
Application: Type B is typically used for heavy-duty appliances such as hair dryers, kettles, and heaters. Type O is typically used for heavy-duty appliances such as hair dryers, kettles, and heaters.

Type B and Type O Compatibility

Type B in Type O Sockets: Generally no. A Type B plug (Two flat parallel pins plus round grounding pin (4.8mm diameter)) does not fit a Type O socket (Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin)) without a travel adapter. Next, check is a type A plug compatible with a type M socket.

Type O in Type B Sockets: Generally no. A Type O plug (Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin)) does not fit a Type B socket (Two flat parallel pins plus round grounding pin (4.8mm diameter)) without a travel adapter.

If you're planning a trip, tell us which country you're visiting and we can confirm whether you need a Type B or Type O travel adapter.

Type B vs Type O plug comparison: Type B and Type O wall sockets and plugs side by side, with the verdict and which way each plug fits, a specification table, key differences and how to tell them apart. Verdict: Not Compatible. — Type B vs Type O Plug: Differences and Compatibility (Infographic)

Does a Type B plug fit into a Type O socket?

Generally no. A Type B plug (Two flat parallel pins plus round grounding pin (4.8mm diameter)) does not fit a Type O socket (Three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin)) without a travel adapter.

Are Type B and Type O plugs the same?

No. Type B follows the NEMA 5-15 standard and Type O follows TIS 166-2549 — they differ in voltage rating.

Which countries use Type B and Type O plugs?

Type B plugs are used in 54 countries, including United States of America, Japan, Vietnam, Thailand, Canada. Type O plugs are used in 1 countries, including Thailand. 1 countries use both, including Thailand. You might also want does a type C plug fit into a type L socket.

How can you tell a Type B plug from a Type O plug?

A Type B plug has two flat parallel pins plus round grounding pin (4.8mm diameter), and is grounded. A Type O plug has three round pins in triangular pattern (4.8mm diameter power pins, 4mm grounding pin), and is grounded. The quickest tell is pin size and spacing — compare the two pin configurations above.