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.
This method is very effective.
An effective treatment was found.
Often used for validity, efficacy, or being in effect. Common for medicines, tickets, contracts, and technical contexts.
This medicine is effective for colds.
This ticket is valid until tomorrow.
Literally 'has an effect'. A very common and natural way to say something is effective.
Exercise is effective for health.
Emphasizes the tangible effect, often used for medicine or immediate results.
This medicine is effective immediately.
Describing that something is effective in terms of cost, time, or resources.
Describing a person who is effective at their job or in achieving goals.
Describing that a law, contract, or rule is in effect or valid.
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.
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.
The new policy has been very effective.
We need to find a more effective solution.
This project is cost-effective.
その契約には法的効力がある。
That contract has legal effectiveness.