- tbf
- group birthday card
- Sister birthday wishes
Sister birthday.
What to write.
Tell her one thing only a sibling would know, then wish her a good day. Shared history is what makes a sister's card.
The lines below are sorted by who is writing. Pick your group, add a memory, then sign.
Updated
Sister lines
Pick your group, add one memory, and sign.
From a sister
Happy birthday to the person who knows everything and tells nothing. I love you.
We have shared a room, clothes and secrets. Happy birthday, sister.
Happy birthday. You are still the first person I ring.
To my sister: thank you for lending me your life as a rehearsal for mine.
Happy birthday. Mum is still your favourite and we both know it.
Another year of you being right about most things. Happy birthday.
From a brother
Happy birthday. I will deny writing anything this nice.
To my sister: you turned out well. Do not let it go to your head.
Happy birthday. Thanks for never telling Mum about the important things.
You are the best sister I have. Do not tell the other one.
Happy birthday. I mean every word of this card, which is rare.
Growing up with you was chaos. I would not change a day of it.
From a younger sibling
Happy birthday to the sister who let me tag along. I am returning the favour by being here today.
You set the bar high and then helped me over it. Happy birthday.
Happy birthday. I stole your clothes, your music and your friends, and I am sorry about one of those.
To my big sister: thank you for the path you cleared. It made mine easy.
Happy birthday. Being the younger one was the best deal in the family.
For a sister-in-law
Happy birthday. We are glad you married into this family, and gladder every year.
To a wonderful sister-in-law: have a lovely day. Lunch soon.
Happy birthday. Thank you for making my brother bearable.
Wishing you a happy birthday and a year as kind as you are.
Happy birthday. The family got better the day you joined it.
Funny
Happy birthday. You are older, I am wiser, and neither of us has changed.
Another year, and you still owe me five pounds from 2011.
Happy birthday. I would have got you a present, but I am your present.
You are my sister, which means I am legally allowed to say you look tired.
Happy birthday. Smile. The photos go in the group chat.
Short
Happy birthday, sis.
Have a great day. Love you lots.
Happy birthday. Proud to be your sibling.
Another year of you. The best.
Happy birthday. Cake is on me.
What to leave out
Do not bring up the old argument, even as a joke. Birthdays forgive a lot, but not that.
Do not write about her age if yours is close to it. She will do the maths.
Do not sign for the whole family unless they asked. Your line is yours.
One card from the family
Brothers, sisters, parents, the cousins. One link, and it opens on her birthday.
- 01
Add her birthday.
The card opens that morning and not before.
- 02
Ask the family.
Each person gets one link and writes once, in a browser.
- 03
She reads it over breakfast.
Every line signed with a name. She keeps it.
Questions
What should I write in my sister's birthday card?
One memory only the two of you share, and one wish for her year. Sisters keep the specific cards and recycle the generic ones.
How do I write a funny birthday message for my sister?
Tease her about something small and true, then say something kind. The kind line is what lets the tease land.
What do you write for a sister-in-law?
Something warm and short. You are not expected to know her childhood, so wish her a good day and sign with your name.
Is it odd for a brother to write a long card?
No. Short is the habit, but one honest sentence from a brother is the line she will remember.
On 22 September 2026 the UK search table gave 750 searches a month for birthday wishes for sister, and the ranking pages mixed brothers and sisters together with nothing from either.
Part of group birthday card.