How to Split the AC Bill With Roommates (2026)

It’s 92 degrees outside. Your roommate keeps the AC at 68. You’re fine at 74 and you barely use it because you work all day at a coffee shop. The bill just came in: $187. They want to split it evenly. You do not.

If you’re trying to figure out how to split the AC bill with roommates without it turning into a passive-aggressive thermostat war, here’s the short answer: split it by actual usage, not by the lease. Even split sounds fair until one person treats the apartment like a meat locker and the other is paying for their habit.

What’s the fairest way to split an AC bill?

Three methods work in real apartments. Pick the one that matches how different your usage actually is.

Even split works only if both roommates are home a similar amount AND prefer similar temperatures. If you both WFH and both like it at 72, just split it. Done.

Usage-weighted split is for when one person is home way more. If your roommate is home 6 days a week and you’re gone 4 of them, a 60/40 split for the cooling portion of the bill is the right answer. Bills typically jump $80–$150 in July and August — that’s the part that gets weighted.

Per-degree split is the nuclear option for thermostat fighters. Whoever wants it below 72 pays a bigger share. You agree on a baseline (say, 74), and the person who insists on colder pays the difference. It sounds petty but it ends the fight permanently.

How much does AC actually add to the electric bill?

A central AC unit running constantly in a 2-bedroom adds roughly $80 to $200 to your monthly electric bill in peak summer, depending on the climate and unit efficiency. Window units run about $30 to $60 per unit per month. The point: it’s not pocket change. It’s worth getting the split right before August hits.

If you want to actually measure it, compare your May bill (AC off) to your July bill (AC on). The difference IS the cooling cost. Everything else — fridge, lights, devices — stayed roughly the same. That delta is what you negotiate over, not the whole bill.

What if one roommate blasts the AC and the other doesn’t care?

This is the most common version of the fight, and it’s the one where even splits feel insulting. You have two options.

Option one: the heavy user pays more. Set a baseline temp (74 is common), and whoever drops it below pays a premium — say, an extra 60/40 weight on the cooling portion. If your roommate keeps it at 68 all summer, they’re paying for the cold they wanted.

Option two: smart plug + window unit. Buy a portable AC for the cold-loving roommate’s room. They pay for it, they pay to run it, and the common areas stay at a temp everyone can live with. Costs $200 upfront, saves months of resentment.

If your roommate also won’t pay their share on time, that’s a separate problem — here’s how to ask your roommate to pay you back without being weird.

How do you bring up the AC bill split without a fight?

Don’t wait until the $200 bill lands. That conversation goes badly every time because someone is already on the hook.

Bring it up before the heat wave. Something like: “Hey, last summer the electric jumped to like $190. Can we figure out a split now so it’s not weird later?” That works because nobody’s defensive yet. Nobody owes anything.

If they push back on a weighted split, the move is simple math: pull up the May bill and the July bill, show the difference, ask them how often they’re home vs. you. Numbers are harder to argue with than feelings.

homies takes the math out of it

homies tracks shared bills automatically and lets you split each one differently — even on the same account. AC bill 60/40? Wi-Fi 50/50? Groceries by who actually shops? You set it once, and the app sends reminders, splits the charge, and shows who owes what. No spreadsheets, no Venmo requests, no fight about who left the thermostat at 68.

rooming, minus the drama. Join the waitlist at joinhomies.app.