How to Split Utilities Between Roommates (When One Works From Home)
How to split utilities between roommates fairly when one person works from home, with a real electric-bill example and honest math.
The question of how to split utilities between roommates gets a lot simpler when everyone’s out of the apartment nine hours a day. It gets complicated fast the moment one roommate starts working from home full-time and the electric bill jumps $60 in a month that nobody else’s habits changed. Splitting that bill three ways like nothing happened isn’t fair to the other two. Making the WFH roommate eat the whole increase isn’t fair either, since they’re still using the same fridge, the same water heater, the same base electrical load everyone else benefits from.
The baseline-plus-surcharge model for how to split utilities between roommates
The model that holds up best is baseline plus surcharge: figure out what the bill costs when nobody’s home all day, split that evenly since it’s the fixed cost of running the apartment, then split whatever’s above that baseline based on who’s actually driving the increase. It sounds more formal than it is. In practice it’s two numbers and a conversation, not a spreadsheet.
The mistake most households make is either ignoring the change entirely (splitting the new, higher bill evenly, which quietly overcharges the roommates who didn’t change anything) or over-correcting (making the WFH roommate pay the entire increase, which ignores that a fridge, router, and water heater run all day regardless of who’s home). Baseline-plus-surcharge sits between those two and is easy enough to explain to a roommate who’s skeptical of the whole idea.
A real jump: $90 to $150
Say the electric bill ran $90/month for three roommates before anyone worked from home, split evenly at $30 each. Then one roommate, call him Marcus, starts working from home full-time. The bill jumps to $150. Splitting the new total evenly would mean Marcus’s roommates suddenly pay $50 each for a change in usage that has nothing to do with them, which is where the resentment starts.
A fairer approach: treat the original $90 as the shared baseline, and split it evenly since that’s the cost of running the apartment regardless of who’s home. The $60 increase is the usage-weighted surcharge, and Marcus, whose AC and monitor are running eight extra hours a day, absorbs most of it. A reasonable split of the increase is 70/15/15:
- Baseline ($90 split evenly): $30 each
- Increase ($60 split 70/15/15): Marcus $42, roommate B $9, roommate C $9
- Final totals: Marcus $72, roommate B $39, roommate C $39
Marcus pays more than double what he used to, which is honest given he’s the one driving the increase, but his roommates aren’t stuck absorbing a bill spike they didn’t cause either. Track this for two or three months and you’ll have real numbers instead of a guess, which makes the percentage easier to defend if anyone questions it later.
Don’t nickel-and-dime the kilowatt-hours
Here’s the honest part most guides skip: you cannot and should not try to calculate this to the cent. Trying to figure out exactly how many kilowatt-hours Marcus’s monitor used versus his laptop charger is a waste of an evening and it will make your household feel like it’s run by an auditor. Pick a round percentage split for the increase, revisit it if the bill changes significantly (new season, new WFH schedule), and let small month-to-month variation go. The goal is a split that feels roughly fair and takes five minutes to apply, not one that’s mathematically perfect and takes a spreadsheet to maintain.
What actually needs adjusting vs. what doesn’t
Internet usually stays split evenly no matter who’s home, since everyone streams and browses regardless of location. Water rarely changes enough to bother adjusting unless someone’s doing several extra loads of laundry a week. Electricity is the one that actually moves when someone’s home all day running AC or heat, so it’s the one worth the baseline-plus-surcharge treatment. If you’re also untangling the rest of the household’s shared costs, how to split rent and utilities without fights covers the full system, and if rent itself needs a similar fairness pass because the rooms aren’t equal, splitting rent by room size walks through that formula.
If you’re the one tracking the baseline and the surcharge every month by hand, that’s exactly the kind of recurring math SPLIIT is built to hold onto instead of you. Set the split once, log the bill each month, and everyone sees their share automatically — it’s free on iOS and Android.
Bring it up before the bill, not after
The best time to propose this split is when someone announces they’re going full-time remote, not two months later when the bill has already spiked twice and someone’s already annoyed. A short, direct message works: “Since you’re home all day now, want to figure out a fair way to split the electric bill? I don’t think even splits make sense anymore, but I also don’t think you should eat the whole increase.” That framing puts you on the same side of the problem instead of accusing anyone of running the AC too much.
Grocery costs tend to shift with WFH schedules too, since the person home all day ends up cooking more, so it’s worth reading how to split groceries with roommates if that’s the next friction point in your house. Utilities are rarely the only thing that needs recalibrating once someone’s schedule changes; they’re just usually the first one anyone notices. If you’d rather just settle the numbers than keep having the conversation, SPLIIT is free on iOS and Android and it’ll keep the baseline and the surcharge straight for you every month.