Translation guide
Describes a person, thing, or information that cannot be trusted or depended on. Japanese uses different words depending on whether you mean a person's character, the accuracy of information, or the dependability of a system.
Describing a person who cannot be trusted to keep promises, tell the truth, or act responsibly.
The most common and natural way to say someone is unreliable. Literally 'does not become a reliance'. Used for people who are not dependable.
彼は頼りにならない。
He is unreliable.
Describing information, data, news, or a source that may be false, inaccurate, or not trustworthy.
General term for information or sources that are not trustworthy. Used for news, statistics, websites, etc.
その情報は信頼できない。
That information is unreliable.
Describing a device, system, method, or plan that does not work consistently or cannot be depended on.
頼りにならない is about dependability (can you count on them to do something?), while 信用できない is about trustworthiness (can you believe what they say?). Use 頼りにならない for a flaky friend, and 信用できない for a liar.
彼は時間を守らないから頼りにならない。
He's unreliable because he's never on time.
彼は嘘をつくから信用できない。
He's unreliable because he lies.
The direct translation '信頼できない' is not always natural for people. For describing a person's character, '頼りにならない' or '当てにならない' are more common in everyday speech.
That person doesn't keep promises, so they're unreliable.
Emphasizes that the person cannot be trusted or believed. Often used when someone has lied or broken trust.
彼の言うことは信用できない。
What he says is unreliable (can't be trusted).
Similar to 頼りにならない but slightly more casual. Means 'can't be counted on'.
彼は当てにならないから、自分でやったほうがいい。
He's unreliable, so you'd better do it yourself.
Means irresponsible, half-hearted, or sloppy. Implies the person doesn't take things seriously.
彼は仕事がいい加減だ。
He is unreliable in his work (does sloppy work).
This site uses unreliable sources.
Means uncertain or unreliable. Often used for information that is not confirmed or is vague.
その噂は不確かな情報に基づいている。
That rumor is based on unreliable information.
Means suspicious, dubious, or shady. Used for sources or information that seem unreliable or questionable.
そのニュースは怪しい。
That news is unreliable (suspicious).
Means unstable or unreliable. Commonly used for internet connections, software, machinery, etc.
このアプリは不安定でよく落ちる。
This app is unreliable and often crashes.
Can also be used for things or methods that are not dependable.
この天気予報は当てにならない。
This weather forecast is unreliable.
Literally 'low reliability'. A more technical way to describe systems or data.
このシステムは信頼性が低い。
This system is unreliable (has low reliability).