What to actually say
Open with this, more or less word for word: I want to bring up the rent split, because the room sizes aren't equal and I don't think the rent should be either.
I've been paying the same as you for a room that's noticeably smaller, and it's been bothering me for months — I should have brought it up sooner.
Names the fact plainly and owns the delay so it doesn't land as an ambush.
I'm not asking you to feel bad about it, I just want us to split it in a way that matches the actual size difference.
Separates the ask from blame, so it reads as a math problem instead of a character problem.
What would you think is fair, given the size difference?
Puts them on record with a number first, which is harder to reject later than a number you handed them.
If we can't agree on a number, let's just measure the rooms and split it proportionally, so it's not either of us deciding.
Offers a neutral tiebreaker so the disagreement doesn't turn into a standoff of opinions.
How it usually goes
A version of the conversation with the push-back left in, because that is the part you need to have already heard once.
What not to say
You know this isn't fair, right?
Turns it into a test of their character instead of a proposal, which forces them to either confess or fight you.
I've been letting this slide because I didn't want drama.
Sounds patient on the surface but plays as martyrdom, and roommates hear the blame hiding inside it.
Everyone who's seen this place says it's unfair.
Brings outside opinions in as ammunition, which turns a two-person conversation into two-against-one.
If they say the lease already settled it
Some people treat the signed number as sacred, as if renegotiating means someone broke a promise. It didn't — you split evenly because neither of you had measured anything yet, you just guessed. Don't argue about the old number, argue about the current facts. Say: 'The lease is just where we started before we knew the rooms were different, I'm asking to update it now that we do.' If they still won't move, ask for a smaller fix instead of the full one — a discount instead of a proportional split — because half a win beats a fight neither of you can undo in a shared kitchen.
