the difference between きっと and 必ず

What do きっと and 必ず（かならず）mean?

I can remember when I first was introduced to the difference between きっと and 必ず. Someone offered to drop me off somewhere and pick me up later. However, they needed to be home at a certain time so they told me I would need to be ready for them at 10:00 pm. I said, 「間に合うように、きっと10時までに用事を終わらせます。」” I will be sure to finish my business by 10 in order to be on time.” He said ‘No’, not 「きっと」,「必ず」. In my mind that meant the same thing but he was serious and 「必ず」was more serious. Both of the words translated to ‘definitely’ but they are not exactly the same.

What is the Difference?

きっと and 必ず are used in a lot of the same situations but can have a slightly different meaning or be completely different. In the situation, I described I could have used either one but 必ず is used to show more certainty than きっと. If you have high expectations for something you would use きっと. On the other hand, if you are highly certain or know something to be the fact you would use 必ず.

https://japaneseuniverse.com/2024/02/18/pac-man-in-japaneseconcepts-behind-development-to-global-icon/

Hoping and being Certain

Ok, so let’s say you have been waiting all day for your friend. She told you she would come to see you later. It is starting to get late but she is nowhere in sight. You are sure she has not forgotten about you and you say to yourself 「きっと来る」.

In this example, きっと is used to show you hope your friend will come and that you trust she will come. You really don’t know for sure though as she may decide she has better things to do and not show up. If you said 「必ず来る」” (my friend) will definitely come” then it sounds like you know something that will make it inevitable that your friend will show up eventually.

Definitely and Highly Likely

Another example of how these two words differ. Anyone that has a cat knows they have very specific routines. If you have a cat that always wants to be fed after waking up you could say 「うちの猫は起きると必ず『ご飯チョウダイ』とおねだりする」” My cat always begs for food when he wakes up”.

Now, again cats are also spontaneous creatures and you don’t always know what they are planning but you can often figure it out. Let’s say the cat likes to wake you up in the morning but does not necessarily do it every morning. After turning out the lights you see a silhouette of something small with pointy ears in the doorway looking in your direction and you realize you did not play with your cat that day. You are sure that he will wake you up tomorrow and say, 「明日きっと起こしに来る」” He is definitely going to wake me up tomorrow.”

If you want to learn more Japanese I reviewed a dictionary of grammar series which I personally recommend and use myself.

I also have several other posts on various topics on Japanese Universe if you are interested.