ただの・
Two everyday words for "only". ただの comes before a thing: "just a", and nothing more. たった comes before an amount: "a mere", and that is very little.
before an amount
Only three people came to the party.
Just a
ただの + noun
A thing or a person: ただの風邪, ただの友達.
A mere
たった + amount
A number with its counter, or これだけ. だけ or しか…ない often follows the amount: たった三人だけ.
ただの: just a
There is nothing more to it, so it reassures, or plays something down. It is what conversation says where writing has にすぎない.
It's just a cold. Please don't worry.
He and I are just friends.
It started as just an argument, but it turned into such a scene that even the police were called.
たった: a mere
The amount is small in your eyes, which can be good news or bad. Before a number, often a price, people also say たったの. Careful writing has わずか.
It's only a five-minute walk to the station.
This was only a hundred yen.
What? Is this all?
Which one?
I'm just a student.
What you are, and nothing more.
There is just one student.
How many, and that is few.
English "just" does both jobs. Japanese has a word for each.
Close neighbours
だけN5
The plain "only", after the word. After a noun it shuts everything else out: 学生だけ is "students and nobody else", not "just a student". After a verb it does the job of ただの.
I'm just a little tired.
しか～ないN4
"Only" with a negative verb: after an amount, usually less than you wanted. たった often stands in front.
We needed ten people for the meeting, but only three came.
にすぎないN2
The written "merely", after the noun. 単なる is a more formal ただの.
That is nothing more than a rumor.
でしかないN2
A blunt "nothing but", after the noun. ただの often comes with it.
To him, I'm just a friend and nothing more.
Check yourself
1Which one fits?
大丈夫、
Choose an answer to see why.
2What does the person saying this think?
お客さんは、
Choose an answer to see why.
More detail
たった今 is "just now": only this moment ago.
The train has just left.
ただの…じゃない is "no ordinary".
This is no ordinary cold. You should see a doctor.
Before a verb the word is ただ, with だけ after the verb.
I was only asking.
More sentences
There's nothing special about it. It's just something I do every day.
He was only a guest, but he behaved as if he were the master of the house.
She started this shop all by herself.
Don't give up after just one failure.