Fair split calculator: how should couples split bills?
Splitting everything 50/50 feels fair — until one of you earns a lot more. Put in your pay and your shared costs to compare an even split with splitting by income, and see what each of you has left.
After tax.
After tax.
Rent or mortgage, groceries, power, internet…
Split 50/50
50% / 50%
You put in
$2,100
a month
Partner puts in
$2,100
a month
You keep
$5,400
for yourself
Partner keeps
$2,900
for themselves
Split by income
60% / 40%
You put in
$2,520
a month
Partner puts in
$1,680
a month
You keep
$4,980
for yourself
Partner keeps
$3,320
for themselves
Split by income, you each put in 34% of your own pay. Split 50/50, you put in 28% of yours and your partner puts in 42% of theirs.
50/50 or by income: what's the difference?
With a 50/50 split, you each pay half of the shared costs in dollars. With a split by income (also called a proportional split), you each pay the same percentage of your pay, so the higher earner puts in more dollars.
Say one of you takes home $7,500 a month, the other $5,000, and your shared costs are $4,200. Split 50/50, you each pay $2,100 — about 28% of the first person's pay but 42% of the second person's. Split by income, the first pays $2,520 and the second $1,680: 34% of each person's pay, and both of you keep the same share of your own money.
Which should you choose?
There's no right answer — only the one you both agree feels fair. Couples often choose:
- 50/50 when incomes are similar, or when you'd both rather keep things simple.
- By income when there's a real gap, so the lower earner isn't left with little of their own.
- A mix — splitting the essentials by income and fun things 50/50, or each covering certain bills outright.
Whichever you pick, it helps to revisit it when something changes: a new job, a pay rise, parental leave, or one of you going part-time.
Keeping the split fair as life changes
A calculator gives you today's answer. Incomes, bills and plans keep moving. Duet connects both of your banks and keeps the split current — showing what each of you has actually put in against your agreed split, so nobody has to keep a spreadsheet or have the awkward conversation.
Common questions
Is splitting bills by income fairer than 50/50?
It depends what you mean by fair. A 50/50 split means you each pay the same dollars; splitting by income means you each pay the same share of your pay. When your incomes are close the two barely differ. When one of you earns a lot more, 50/50 can leave the lower earner with far less of their own money each month.
Should we use take-home pay or salary before tax?
Take-home pay usually gives the truest picture, because that's what actually lands in your accounts. Before-tax salary works too — just use the same kind of figure for both of you so the comparison is like for like.
What counts as a shared cost?
Whatever you both benefit from and agree to share: rent or the mortgage, groceries, power, gas, water, internet, insurance, the car you both use, and pet costs. Personal spending — your own clothes, hobbies, lunches — usually stays out.
What happens to the split if one of us goes on parental leave or part-time?
A split by income follows the change automatically: when one income drops, that person puts in less and the other more, so neither of you is suddenly short. A fixed 50/50 split stays the same, which can leave the person on leave paying the same bills on a much smaller income.
Do we need a joint account to split bills?
No. Many couples each pay their share into a shared account that the bills come out of; others keep separate accounts and settle up. Either way works with either split — the calculator just tells you how much each person puts in.
See the split with real numbers
Explore Duet with a demo couple: their split by income, and what each of them has actually put in this month. No sign-up needed.
General information only. Duet Money isn't a licensed financial adviser — these figures are arithmetic on the numbers you enter and don't take your personal circumstances into account. Consider speaking to a licensed adviser before making decisions about loans, tax or investments.