Updated August 2026
How much should each of you pay? Enter both incomes and your shared expenses, and the calculator instantly shows the numbers for all three models: 50/50, proportional to income and the shared pot (joint budget).
Rent or mortgage, utilities, internet, groceries, subscriptions you share.
The results are indicative and based on the net incomes and expenses you enter. The right model is a conversation, not a formula — the calculator just puts the numbers on the table. This is not financial advice.
50/50 — each partner pays half of the shared expenses. It's the simplest possible deal and works well when the incomes are close. When they're not, it's equal in money and unequal in effort — the percentages above show exactly how unequal.
Proportional to income — each partner contributes the same percentage of their own income. Your share = your income ÷ your combined income × shared expenses. It's the model where the split feels the same for both of you, even when the amounts differ — and it's the reason this calculator exists: the formula is simple, but nobody enjoys running it on paper every month.
The shared pot — also called a joint budget or joint finances: both incomes go into a joint account, expenses come out of it, and whatever remains is split equally as each partner's spending money. It's the easiest to keep up day to day and demands the most trust. In practice you no longer split the expenses — you split what's left after them.
A round-number example: incomes of $4,500 and $9,000, shared expenses of $4,000. At 50/50, each pays $2,000 — which is 44% of the smaller income and 22% of the larger one. After the shared expenses, one partner has $2,500 left for all their personal spending, the other $7,000. Equal in money is not equal in effort.
That doesn't make 50/50 a bad model — with similar incomes it stays the simplest one, with the least to negotiate. It just means it's worth calculating rather than guessing. Many money arguments in couples don't come from bad faith; they come from nobody ever putting the numbers side by side.
The model is a one-line formula. The hard part is the numbers inside it: what your shared expenses actually are, month after month — not the in-your-head estimate, which is almost always lower than reality. For that you need one place where you both log — a notebook, a sheet or an app, as long as it's a single one. I've written separately about what a couple's budget that actually works looks like.
There is no single "fair" — there are three models most couples use: 50/50 (each pays half), proportional to income (each contributes the same percentage of their own income) and the shared pot (both incomes go in, personal money is split equally). The fair one is whichever you both feel is fair and can keep up without arguing about it every month. The calculator above shows the numbers for all three.
Each partner's share = their income ÷ combined income × shared expenses. With incomes of $4,500 and $6,500 and $4,000 of shared expenses, the partner earning $4,500 pays $1,636 and the one earning $6,500 pays $2,364 — both contribute the same share of their own income, about 36%.
It is equal in money, not in effort: the same amount can be 44% of one income and 22% of the other. With similar incomes, 50/50 stays the simplest model; with a big gap, everything weighs much harder on the smaller income — which is why many couples switch to proportional or to a shared pot.
Typically: rent or mortgage, utilities, internet, groceries, subscriptions you use together, and everything that belongs to the shared household. Personal spending — hobbies, clothes, each partner's nights out — stays out, and so do gifts between you. Where exactly you draw the line is a couple's decision; what matters is drawing it once, not at every receipt.
In one place, where both of you log — otherwise "shared expenses" becomes a guess, and any splitting model runs on wrong numbers. In Monavo, partner mode connects two phones with a QR code: each of you logs from your own phone, you see the same budget, and every expense shows who added it. One subscription covers both phones.
There's no single "right" amount — it depends on your incomes and the model you pick. As a rule of thumb: at 50/50, each pays half of the shared expenses; proportionally, each partner's share = their income ÷ your combined income × shared expenses. The calculator above gives you the exact amounts for both.
The same way as the rest of the shared expenses: either half-half or in proportion to income. Rent is where the difference shows most, because it's the biggest number on the list — with incomes of $5,000 and $8,000, a $2,600 rent means either $1,300 each (26% of one income, 16% of the other) or $1,000 and $1,600, the same percentage for both. Put the rent into the calculator together with the rest of your shared expenses and see both options.
Net income — the money that actually lands in your accounts each month. Splitting on gross means splitting money you don't actually have. If your income varies month to month, use an average of the last 3 months.
Monavo is a personal expense-tracking app for iOS and Android. Free, local-first, no bank linking. See how quick add works →
The calculator told you how to split. Monavo shows you what you actually spend, month after month: connect your phones with a QR code, each of you logs from your own, and every expense shows who added it. One subscription covers you both.