How to split rent by income

What it means

In an equal split, a $2,400 rent between three people is $800 each. That is simple, but $800 is a very different bite out of a $3,200 monthly income than out of a $5,200 one. An income-based split fixes that by making each person’s share of the rent match their share of the household’s total income.

There is no official or legal formula for this: it is an agreement between the people who live together. It tends to work best for couples and for friends who trust each other with their numbers, and where incomes are noticeably different.

The formula

Add up everyone’s monthly income to get the household total. Divide your own income by that total to get your percentage. Multiply the percentage by the rent.

Your share = (your income ÷ everyone’s income added together) × rent

Do this for each person and the shares always add up to the rent, apart from a possible rounding difference of a cent or two, which the next section handles.

A worked example

Three roommates share a $2,400 apartment. Sam earns $5,200 a month, Alex $3,200 and Maya $4,000, so the household total is $12,400.

Notice what the split achieves: everyone ends up paying about 19.4% of their income in rent. With an equal split, Sam would pay 15.4% of income and Alex 25%.

Where the odd cent goes

The exact shares are $1,006.4516, $619.3548 and $774.1935, which round down to a total of $2,399.99. The missing cent goes to the person with the largest left-over fraction, here Alex, so the total is exactly $2,400.00. This “largest remainder” rule is the one Halfup uses, so the same bill always splits the same way.

When it is fair, and when not

Income-based splits suit households where people have clearly different earnings and share the whole home equally, for example common rooms and similar bedrooms. They suit couples especially well, because money is often pooled in some way anyway. See how couples can split bills fairly for more.

They fit less well when the bedrooms are very different. A person with a modest income in the largest room with its own bathroom may reasonably be asked to pay more than their income share alone suggests. In that case consider splitting rent by room size or a mix of the two.

Also think about what counts as income. Salary, freelance earnings, benefits and regular family support all affect what a person can afford. Irregular income is easiest to handle by using the average of the last six to twelve months.

A common budgeting rule of thumb says to keep housing to roughly 30% of income. It is only a guide, but it is a useful sanity check: if an equal split pushes one person far above it and another far below, an income split is probably worth discussing.

How to agree on it

1. Decide whether to use gross or net income, and use the same one for everyone.
2. Share the figures privately if you prefer: only the resulting percentages need to be visible to the group. In Halfup the incomes you type into the income helper stay on your phone, and only the percentages are saved.
3. Write down the percentages and the date to review them.
4. Use the same percentages for shared bills too, or choose a separate rule for each bill. See fair ways to split bills between roommates.

Halfup applies the rule you choose to every bill and records each payment, so you do not need to redo the sums every month. Halfup never moves money: you pay each other the way you already do.

Common questions