Translation guide
How to refer to or address your grandfather in Japanese, depending on formality, family context, and whether you're talking about your own or someone else's.
My grampa (humble)
Grampa! (addressing your own)
Your grampa (polite)
You want to call your grandfather directly, like 'Grandpa' in English.
The most common, affectionate way to address your own grandfather. Used by children and adults within the family.
Grandpa, do you want to eat this?
A more casual, slightly rough but still affectionate form. Often used by boys or in very informal settings.
Hey Gramps, how are you?
A baby-talk or very cute form, often used by small children or when speaking to small children about their grandfather.
Grandpa, pick me up!
You are talking about your own grandfather to someone outside your family, like a teacher or colleague.
The standard humble/polite term for your own grandfather when speaking to outsiders. Use this in formal contexts.
You are talking about a friend's or colleague's grandfather.
You are talking about or addressing an old man who is not your relative.
Using おじいちゃん to refer to someone else's grandfather sounds childish or overly familiar. Use おじいさん instead.
I met my friend's grampa. (unnatural)
My grandfather will be 80 this year.
Polite way to refer to someone else's grandfather. Also used to address an elderly man in general.
Mr. Tanaka's grandfather is very healthy, isn't he?
Very polite and respectful, sometimes used in formal letters or when speaking to someone of higher status about their grandfather.
Please give my regards to your grandfather.
Can be used to address or refer to an elderly man politely, similar to 'mister' or 'sir' for an old man.
Let's ask that old man for directions.
I met my friend's grandfather. (natural)
In some families, grandchildren call their grandfather by his first name + おじいちゃん or just by a nickname. This is less common but possible.