Effective means producing the result you want; efficient means producing it without wasting time, money or effort. The two are easy to mix up, but English keeps them apart. That's why one solution can be effective but not efficient: taking a taxi to work every day gets you there on time, but it costs a lot. Taking a taxi every day is effective, but not efficient.
effective or efficient — can you pick the right one?
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an effective way/method/treatment; effective against + problem; an efficient system/worker; efficient use of + time/money/energy; energy-efficient
- This cream is very effective against mosquito bites.
- Our new dishwasher is more efficient and uses half as much water.
- She is very efficient: she answered all her emails before lunch.
What changed
First versionThe new heating system is more effective: our bills are 30% lower now.
RevisionThe new heating system is more efficient: our bills are 30% lower now.
The bills are lower, so the system uses less energy and money. That's about saving, so it's efficient. Effective would only say that the system heats the house better, and it says nothing about the bills.
Effective also has an official meaning, coming into force: The new rules are effective from 1 May, that is, they apply from 1 May. Efficient isn't used like that.
Your turn
This car is very ___: it uses only four litres of fuel per 100 kilometres.
Show the answer
efficient — Using little fuel per 100 kilometres is about saving, so it's efficient. Effective describes something that gets results at all, but here the car is judged by its fuel consumption.
Talk about a habit that helps you save time at home or at work. Say exactly what you do and how much time it saves.
Cooking meals for three days on Sunday is my most efficient habit: it saves me about an hour every evening.
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