Sharebirch is a free rent split calculator for shared homes. Enter the rent and each bedroom's size, choose how much of the rent pays for the kitchen and living room (or work it out from the floor area), add an extra for a private bathroom or a discount for a room with no window, and set two people for a couple's room. Shared costs can follow income, bills can be split equally or by income, and a parking space is charged to the room that uses it.

The result compares equal and size-only splits and exports as a share link, CSV or printable agreement. Two companion calculators prorate rent for a mid-month move under three day counts, and split a couple's bills three ways. Everything runs in the browser; no account.