RoomProrate

Split a utility bill when someone moved in or out mid-cycle

Type the dates people lived there and the dates on the bill. RoomProrate counts the days, keeps fixed fees apart from usage, and shows working that adds up to the cent.

  • Counts days from dates
  • Two split methods side by side
  • Nothing leaves this tab
Timeline: Resident A lives in the flat all of April, Resident B moves in on April 16 April electricity, 30 billed days A B B moves in 18152230
Fictional example used by the calculator: usage of 120.00 for April. Daily split gives A 90.00 and B 30.00; person-days gives A 80.00 and B 40.00.

How it works

  1. Step 1

    Who lived there

    Each person with a move-in day and, if they left, a last day.

  2. Step 2

    Which bills

    The billed dates, the usage charges and any fixed charges.

  3. Step 3

    Which agreement

    Daily split or person-days for usage, and who shares the fixed part.

  4. Step 4

    A checked result

    Each share, the working, and a line proving it adds up to the bill.

Calculator

Choose a currency, add the people and the bills, then press Calculate split. Try the fictional example first if you want to see a finished result.

The calculator needs JavaScript. If it does not appear, check that JavaScript is turned on for this site.

How to use it

  1. Pick the currency printed on the bill. One report uses one currency; amounts are never converted.
  2. Add each person with the first day they lived there. Fill in the last day only if they moved out; blank means they stayed to the end of every bill.
  3. Add each bill with the first and last day it charges for. Put the current period's charges in, not the account balance, which can include earlier bills or payments. See reading the billing period.
  4. Split the amount into usage charges and fixed charges if the bill shows both. Leave fixed charges blank if there are none.
  5. Choose the method for usage and tick who shares the fixed charges, then tick the confirmation box. Compare the methods.
  6. Calculate, then download a CSV, print the result, or download a backup to finish later.

Tip: agree on the method with your roommates before anyone sees the numbers. The result table also shows what the other method would give, so nobody is surprised later.

Questions

Is anything I type sent to a server?

No. Names, dates and amounts stay in the memory of this browser tab and the calculation runs on your device. RoomProrate has no account system and no database. Like any website, the host receives ordinary request data such as your IP address when the page loads, but what you type is never part of a request.

Which method should we use, daily split or person-days?

Neither is the single fair answer; they are two different agreements. Daily split shares each day of the bill among the people living there that day, so cost from empty days is left visible as unassigned. Person-days shares the whole usage charge by how many days each person was there, so cost from empty days is spread over everyone. Agree on one before you calculate, and the result shows what the other method would give.

Why are the move-in day and the last day both counted?

Because a person who moves in on the 16th and leaves on the 30th usually expects to pay for 15 days, not 14. Every date in RoomProrate counts both ends. If your bill counts differently, for example its period ends on the day of a meter reading that also starts the next bill, enter the day before as the last billed day.

What are fixed charges and usage charges?

Fixed charges are amounts that do not depend on how much is used, such as a daily standing charge, a connection fee or a flat internet price. Usage charges depend on consumption, such as kWh of electricity. Many bills show them on separate lines. RoomProrate splits fixed charges equally among the people you tick for that bill and splits usage by the method you choose.

What does "Unassigned: vacant days" mean?

With the daily split, a day when nobody lived there has nobody to share its cost. That amount is shown as unassigned instead of being quietly added to someone. The household decides who covers it, for example the landlord, the person who held the lease, or everyone equally.

Why do the shares sometimes differ by one cent?

Money can only be split into whole cents. RoomProrate works with exact fractions, then gives each person the whole cents of their share and hands out the leftover cents one at a time to the largest dropped fractions, with ties settled in a fixed order. The shares and the unassigned amount always add up exactly to the bill.

Can I save my work?

Nothing is saved automatically. Use "Download backup (JSON)" to keep a file on your device and "Restore backup" to load it later. After a restore you confirm the fixed-charge recipients again, because the people or dates may have changed since. "Download CSV" and Print give you a copy of the result to share.

Is the result legally binding?

No. It is arithmetic on the numbers and the agreement you entered. It does not decide who owes money under a lease or a contract, and it does not measure who actually used more power or water.