In this “Dear Splitwise”, we return to the always tricky issue of live-in significant others.
Dear Splitwise,
If my roommate has his girlfriend move in, what would be a fair price for him to pay me additionally? My roommate currently pays $435.00 for his share of the rent out of $995.00 per month. Electric is a total of $210.00 (which we split two ways) and cable is $60.00 each. He only wants to pay $50.00 more per month, which is way too cheap. What would be a fair amount for her share of rent and utilities per month? He’s trying to justify the low amount by saying she’s not going to use TV even though there is TV with cable in his room.
Thanks,
-Soon to be Third Wheel
Hi Third Wheel,
Good question. New live-in significant others can cause lots of stress, and I’m sure other readers share your question.
I’ll assume that your current prices are fair and that the size of your common spaces is “average” – roughly the size of both bedrooms combined. I’ll also assume that his girlfriend is really “moving in,” i.e. does not have her own place.
If she did have her own place, then $65 per month would be about right. It’s not fair to make someone contribute to two different rents just because they are dating. Our research shows that for significant others who technically have their own place (but stay over all the time) a half-share of the utilities is a good compromise. In your case, you would have 2.5 people paying utilities, of which she was half-a-person. So she would chip in $65, or one-fifth share of the $330 in utility bills, with no change in rent prices.
However, you indicated that she is moving in full time. If this is true, his rent should go up to $525 per month, and yours should go down to $470 per month. Why? She will be sharing the common spaces (kitchen, living room) as an equal participant, so the couple should pay a bit more than if there was only one person in the bedroom. This is based on a “price-per-sq-ft” approach of our rent calculator, documented here (and in a rent FAQ here). In this case, the cable and electric bills should be split equally three ways ($110 per person per month), unless there is a vast difference in usage.
I hope this helps and that you won’t have to use the Splitwise Noise Calculator once she moves in!
-Splitwise
With contributions from Benjamin Schenker
The Splitwise Blog 
I have a question about my situation. I’m renting a teeny room and i have a private bathroom with shower too. I’m separated from the rest of the apartment with an accordion room divider. I have a small refrigerator and a microwave in a closet. I don’t have use of any of the common areas at all, in fact, that is the agreement from moving in. My landlord charges $875 for the room and now she is suggesting we split the electric bill have way. I agreed to contribute $50 monthly. What contribution should i fairly pay on an electric bill that is $126 monthly for a three bedroom apartment with huge living room – but I’m only renting & using my room and private bathroom?