Translation guide
The most common and natural way to say 'smartphone' in Japanese is スマホ (sumaho), a shortened form of スマートフォン (sumātofon). While スマートフォン is the full word, スマホ is overwhelmingly used in everyday conversation. Other terms like 携帯 (keitai) or 電話 (denwa) may be used in context, but they are broader and less precise.
smartphone (formal/full word)
Used in formal contexts, product names, or when clarity is needed.
Referring to a smartphone as a physical object or device.
The standard, everyday word for smartphone. It's a contraction of スマートフォン and is used in almost all casual and semi-formal situations.
I bought a new smartphone.
My smartphone screen cracked.
The full, formal word for smartphone. Often used in official documents, product specifications, or when speaking very politely. In daily conversation, it can sound a bit stiff.
The latest smartphone was announced.
Short for 携帯電話 (keitai denwa), meaning 'mobile phone'. This term is broader and can refer to any mobile phone, including older feature phones (flip phones). It's still used, especially by older generations, but it doesn't specifically mean 'smartphone'. Use with caution if you need to be precise.
May not clearly indicate a smartphone; could be interpreted as a feature phone.
I forgot my mobile phone.
Literally 'telephone'. In context, it can mean 'smartphone' when the phone function is implied, but it's very ambiguous. Only use when the context makes it clear you're talking about a smartphone.
Very ambiguous; could mean landline or any phone. Not recommended for clarity.
I left my phone at home.
Referring to the smartphone ecosystem, apps, or using a smartphone for specific functions.
Again, スマホ is the go-to word. It's used naturally when talking about using apps, browsing the internet, etc.
I look at the map on my smartphone.
I made a reservation using a smartphone app.
Used in more formal contexts, such as business or technical discussions about smartphone platforms.
スマホ is the casual, everyday abbreviation and is by far the most common. スマートフォン is the full word, used in formal or technical contexts. 携帯 (keitai) is a broader term for mobile phone, not specifically a smartphone, and is becoming less common among younger speakers. If you want to be clearly understood as referring to a smartphone, stick with スマホ.
Charge my smartphone.
The smartphone penetration rate is high.
Review my mobile phone plan.
In casual conversation, スマホ is almost always the best choice. You can use it in most situations without sounding too informal. Even in semi-formal settings like talking to a store clerk, スマホ is perfectly acceptable. Reserve スマートフォン for very formal writing or when you need to emphasize the technical aspect.
We are developing services for smartphones.