One bill, one rule, one total
A utility bill is easier than rent in one way and harder in another. The total is printed. The fair share is not. Electric, gas, water, and internet arrive as one number for the whole apartment, and the people inside used them differently. If you argue from memory, you will argue about showers and laptop chargers. If you argue from a rule you picked while everyone was calm, you will argue about whether the rule still fits. That second argument is shorter.
Write the bill's total, the dates it covers, and the due date at the top of the note. A $146.28 electric bill for September 2 through October 1 is a different object from "the electric bill." The cents matter because four people splitting a rounded $146 will not match the amount that leaves the account. Use the Bill Split calculator with tip at 0 percent and the tax field at $0 unless the bill itself shows a tax you are splitting separately. The bill total is the number the company will collect.
Decide which utilities are in this split. Some households do electric alone because it swings, and split internet evenly because everyone agreed to the plan. Bundling them into one pot is fine if you say so. Bundling them silently means the person who never streams is subsidizing a choice they did not make, or the opposite, and nobody can point at a line.
Three rules that cover most apartments
Equal split: everyone pays the same. On $146.28 with three roommates, the shares are $48.76 each. 48.76 × 3 = 146.28. There is no leftover cent. Equal is the right rule when usage is similar or when the household has decided that measuring is not worth the mood. Say that out loud so a later heat wave does not feel like a broken promise. The promise was "we do not track."
Nights in the apartment: if someone traveled for half the month, equal may feel wrong. Count nights slept there, or nights the person had access and did not give notice. Suppose the nights are 30, 30, and 16. Weights 30, 30, and 16 sum to 76. The traveler's share is 16/76 of the bill. Run those weights in By share mode. Do not invent a daily rate and then also charge them a full share. One rule only.
By room or by plug: a space heater in one room is a reason to talk, not a reason to guess a percent. If you can see a rough difference and everyone agrees the heavy user pays 50 percent and the other two split the rest, enter custom amounts or weights of 2, 1, and 1. The agreement is the point. A made-up 50 percent that nobody accepted is just a new fight with decimals.
A month with a swing
Electric bills move with weather. A $90 month and a $160 month can both be "normal" for the same apartment. Splitting each month as it arrives is fairer than charging an average that lags the season. If you want the pain to be smoother, build a small utility cushion: each person adds $15 a month to a shared envelope, and the actual bill is paid from the envelope. The split of the bill can still be equal. The cushion stops a heat wave from landing on the same week as rent.
The cushion is not a profit center. At the end of a season, look at what is left and either refund it by the same weights or leave it for the next spike. Write which one you chose. An envelope that quietly becomes one person's savings will end the experiment. So will an envelope that is raided for pizza. Name it on the outside.
If the bill includes a past-due amount, do not split the penalty across people who paid on time. Pull the penalty out, assign it to the person who missed the payment, and split the current charges only. A $15 late fee hidden inside a $161.28 total is a tax on the punctual roommates. Subtract first. Then split $146.28. Show both steps in the message you send.
Who pays the company, and when
One person is usually on the account. That person is floating the bill until the others pay. Agree on a day. "Send your share within three days of the photo of the bill" is a rule. "Whenever" means the account holder is a bank with no interest and no thanks. If the account holder pays a day late because the shares arrived late, the late fee belongs in the next split as its own line, assigned to the delay, not buried.
Pay the person the calculator's row, not a rounded ten. If your share is $48.76, send $48.76. The ten-dollar habit creates a running tab nobody can reconcile in December. If your payment app cannot send cents, send the next cent up and say so, or settle cents in cash once a month. The account holder should not be the one who always eats the rounding.
Keep the PDF or the photo. A text that says "electric is about 150" cannot be checked. A text that says "electric $146.28, equal, you owe $48.76, due Friday" can. When someone moves out, the last bill may arrive after they leave. The agreement should say they still owe their share of the days they lived there. Estimate with nights if the bill is not in yet, then correct it when the PDF arrives. Correcting is fair. Disappearing is not.
What not to mix in
Do not use the rent square-footage weights for the electric bill unless you have a reason that survived a conversation. A larger bedroom does not run a larger refrigerator. The refrigerator is shared. The space heater is not. Internet is often a flat choice you all made, so equal is a good default even when electric is weighted. Water may track with nights better than with rooms. Three utilities can have three rules. Write them in one note so you do not relitigate the philosophy every month.
Do not split a bill that includes another apartment's charges because of a meter mix-up. If the number looks impossible, call the company before you divide it. A $400 bill in a mild month is a reason to read the meter dates, not a reason to send your roommates a larger request. If the company corrects it later, the correction should flow through the same shares. Keep the original split so you can refund the difference without a new argument.
Deposits to start service are not a monthly bill. They belong on the move-in checklist. If one person paid a $100 start deposit, that is a separate IOU, refundable or not according to the company, and it should not be divided into the September usage as if everyone burned an extra $33 of electricity.
A short audit you can do in the group chat
Add the shares. They must equal the bill. If the calculator shows a one-cent difference between people, the rows still have to add to the total. Send the rows, not just the headline. Name the rule in the same message: equal, nights, or weights. Name the dates the bill covers. Name the day you need the money.
If someone disagrees, the disagreement should be about the rule or about a fact, such as nights away. It should not be about the multiplication. You can redo a $146.28 equal split on any phone. 146.28 divided by 3 is 48.76. When the arithmetic is boring, the household can spend its energy on the only real question: does this rule still fit the way we live? Ask that question on a calm weekend, change the rule for the next bill, and do not rewrite the bill you already paid.