Why I Built This Calculator (And Why It Almost Didn't Happen)

Okay, so here's the story of this website. Because I think it's relevant, and because I want you to know that this wasn't some corporate product plan. This was a guy in a small room at 2am, tired of having awkward conversations about money.

It started in Apartment 4. The "no closet" apartment. The garbage truck apartment. I was lying in bed at 2am, listening to the truck hit the dumpster, thinking about how I was paying $800 for a room that was objectively worse than the master suite someone else was paying $800 for.

I opened my laptop. I made a Google Sheet. I called it "Rent Math" because I'm not creative with names.

The sheet had four columns: Roommate, Room Size, Amenities, Rent Share. I put in our numbers. Room 1: 220 sq ft, private bath, $1,005. Room 2: 160 sq ft, shared bath, $733. Room 3 (me): 140 sq ft, no closet, shared bath, $640. Room 4: 180 sq ft, shared bath, $822.

I stared at the numbers. $640. I would have saved $160 a month. That's $1,920 a year. For a room with no closet.

I showed the sheet to my roommates the next day. Jen, the master suite roommate, looked at it and said "huh, that actually makes sense." We changed the rent split. I moved to a better room six months later. The sheet worked.

But the sheet was ugly. It was a spreadsheet. You had to know how to use it. You had to make a copy, modify it, understand formulas. Most people don't want to do that. Most people want a website where they put in numbers and get an answer.

So I learned to code. Not well, at first. I made a terrible version of this calculator in vanilla JavaScript. It had one input field and it broke if you put in a letter. But it worked for basic square footage splits.

Then I showed it to a friend who actually knows how to code. He laughed at it. Then he helped me rebuild it properly. Added income-based splitting. Added amenity adjustments. Added the couple settings. Made it not break when you type letters.

Then I thought: this should be a website. Not just a calculator on my laptop. A real website that anyone can use. Because the problem I had — unfair rent splits — isn't unique to me. It's universal. Every roommate situation has this problem.

So I bought a domain. Rentsplitter.org. It was available and it was perfect. I built the site in a weekend. It had the calculator, three blog posts, and a contact page that went to my Gmail.

That was two years ago. The site has grown since then. More calculators. More blog posts. More features. But the core idea is the same: remove the awkwardness from rent conversations by letting math do the talking.

The calculator doesn't care about your feelings. It doesn't care if you're the person in the master suite or the person in the closet room. It just does the math. And the math is fair.

That's why this exists. Not to make money — there are no ads, no subscriptions, no upsells. Just a tool that solves a real problem I had, that I know other people have too.

If you're using this calculator for the first time: welcome. I hope it helps. I hope it saves you an awkward conversation. I hope it saves you money. And if it does, tell a friend. That's all I ask.

— Jake

P.S. — The Google Sheet still exists. It's in my Google Drive, labeled "Rent Math v1 (archived)." I open it sometimes when I need to remember why I started this. It's terrible. The formulas are broken. The formatting is ugly. But it's where everything began. And I keep it because sometimes the ugly first draft is the most important one.