Translation guide
How to express that something works well, produces the intended result, or is effective in Japanese.
Describing that a method, medicine, policy, etc. is effective or works.
The most common and neutral way to say something is effective. Used for methods, measures, medicines, etc.
この方法はとても効果的です。
This method is very effective.
効果的な治療法が見つかった。
An effective treatment was found.
Often used for validity, efficacy, or being in effect. Common for medicines, tickets, contracts, and technical contexts.
この薬は風邪に有効です。
This medicine is effective for colds.
この切符は明日まで有効です。
This ticket is valid until tomorrow.
Literally 'has an effect'. A very common and natural way to say something is effective.
運動は健康に効果がある。
Exercise is effective for health.
Emphasizes the tangible effect, often used for medicine or immediate results.
この薬はすぐに効き目がある。
This medicine is effective immediately.
Describing that something is effective in terms of cost, time, or resources.
Means efficient, focusing on the ratio of input to output. Often used for work, systems, or energy.
このシステムは非常に効率的だ。
This system is very efficient.
Literally 'cost-effectiveness is high'. Used in business or policy contexts.
このプロジェクトは費用対効果が高い。
This project is cost-effective.
Describing a person who is effective at their job or in achieving goals.
Means competent, capable. Used for people who perform well.
彼は有能なリーダーだ。
He is an effective leader.
Colloquial way to say someone is capable or gets things done.
田中さんは本当に仕事ができる。
Tanaka-san is really effective at work.
Describing that a law, contract, or rule is in effect or valid.
Same as above, but specifically for validity. Also used for tickets, passports, etc.
この法律はまだ有効です。
This law is still in effect.
Refers to legal force or efficacy. More formal and technical.
効果的 (kōkateki) is about producing a good result, while 有効 (yūkō) often implies validity or official efficacy. For medicine, both can be used, but 有効 is more technical. For methods, 効果的 is more natural.
この方法は効果的だが、公式には有効と認められていない。
This method is effective, but it is not officially recognized as valid.
効率的 (kōritsuteki) means efficient, not just effective. If you want to say something works well without focusing on resource use, use 効果的 or 効果がある.
新しい政策は非常に効果的だった。
The new policy has been very effective.
もっと効果的な解決策を見つける必要がある。
We need to find a more effective solution.
その契約には法的効力がある。
That contract has legal effectiveness.