What to write in a birthday letter
Almost nobody is stuck for what they feel. They are stuck for the first line — because the first line decides whether the rest sounds like a greeting card, and everybody can hear a greeting card.
There is one rule underneath everything below, and it is not about being poetic: a detail only you could have written beats any adjective you could have chosen.
Where to start
Start with a fact, not a feeling.
A feeling has to be believed. A fact only has to be recognised — and recognition is the thing that makes someone stop reading and look up.
“I love you and I hope you have the best day” is true, and it is the sentence they will get eleven more of before lunch. “You have heard me tell the same three stories for years and you still laugh in the right places” could only have been written by one person, about one person.
So open with something small, specific, and slightly unflattering to you: a habit of theirs you pretend to be annoyed by, the thing they said once that you never repeated, what the house is like when they are in it. The feeling arrives on its own once the fact is on the page. It almost never arrives the other way round.
Three examples
Three short letters, and what each is doing.
These are the same three the builder offers as starting points. They are deliberately short, and not one of them tries to sum anybody up.
Warm and short
Another year of you, and I still think the world got lucky the day you showed up in it. Happy birthday. Eat the whole cake. I'll cover for you.
It states a compliment as though it were a fact about the world rather than an opinion about them, which is much harder to wave away. Then it undercuts itself with a joke, because four sincere sentences in a row is more than most people can receive without looking at the floor.
For a best friend
You have heard me tell the same three stories for years and you still laugh in the right places. That is the whole friendship, really. Happy birthday, you absolute menace.
One unremarkable detail — laughing in the right places at a story they have heard before — is standing in for years of friendship. It works because it could not have been written about anybody else. “You are the best friend I could ask for” could have been written about anybody.
For a parent
I never say this out loud, so I am writing it down instead. Everything steady in me came from watching you. Happy birthday. I hope today is quiet and easy and entirely yours.
The first line is the whole letter: it names the fact that this is never said out loud, which is what makes writing it down worth anything. Then it stops. It does not itemise everything they did, because a list reads as a summary and a summary reads as an ending.
Rewrite every word of them. They are here to show the shape and the length, not to be sent — a letter that arrives sounding like somebody else is worse than a short one that sounds like you.
What to leave out
Four habits that make a letter worse.
Summarising the relationship
A list of everything they have been to you reads as a retrospective, and a retrospective reads as goodbye. Pick one moment and trust it to carry the rest.
Superlatives
Best, most, always, never. They are the words we reach for before we have thought of the specific thing — and they are the words everybody else reached for too.
Apologising for the letter
“I’m not good at this” and “sorry this is cheesy” hand the reader a reason to discount whatever follows. Write the sentence you were about to apologise for, and delete the apology.
Adding a moral
The last line does not have to mean anything. “Eat the whole cake. I’ll cover for you” is a better ending than a paragraph about what this year will bring.
Length
Three sentences is a finished letter.
Length is not effort. Attention is effort, and attention shows in one specific line in a way it never does in six vague paragraphs.
If you are writing it into a gift on this site there is a second reason to keep it short: the letter is typed out a character at a time while they read it, at a speed you choose. Three sentences land like someone speaking. Six paragraphs land like homework, and they will scroll.