The English language has a lot of similar words amongst its ranks. But while many of these words may be similar to one another, they are not the same. They often carry slightly different meanings or they place a different emphasis on the words around them. Such is the case with our two words today, efficacy vs. efficiency.
In today’s post, I want to go over the differences between these two words. I will talk about their definitions and their functions in a sentence. I will also provide example sentences, so you can see how they work for yourselves.
The word efficacy’s origin dates back to early 16th century: from Latin efficacia, from efficax, efficacy. The word efficiency also originated in late 16th century (in the sense ‘the fact of being an efficient cause’): from Latin efficientia, from efficere ‘accomplish’
Efficacy as noun:
Efficiency as noun:
Efficiency or efficacy:
While these two words are similar, efficiency vs. efficacy have different meanings. Efficacy is about whether or not something can be done at all. Efficiency is about how something is done and if it minimizes waste. In case you are wondering how you’ll remember all of this next time you go to use efficiency or efficacy, here is a neat trick to remember the difference. Efficacy has to do with the capacity to do something. Both efficacy and capacity have the letters “CA” right next to each other. Efficacy also has to do with ability, both of which have the letter “A” in them. When thinking about efficacy, think about capacity and ability. Efficiency has to do with minimizing waste. Something that has a perfect level of efficiency will have no waste. Both efficiency and no have the letter “N” in them. When thinking about efficiency, think no waste.