Monthly budget calculator
Money in as positive lines, money out as negative ones, and the total at the bottom is what is actually left.
The whole budget on one screen
Start from take-home pay — what actually lands in your account, after tax and pension, not your gross salary. Then write every outgoing as a negative number.
take home pay 3200 | + | 3,200 |
rent -1150 | − | 1,150 |
groceries -420 | − | 420 |
transport -180 | − | 180 |
utilities -160 | − | 160 |
subscriptions -45 | − | 45 |
savings -400 | − | 400 |
| Total | 845 |
The 845 at the bottom is genuinely uncommitted — savings has already been taken out as a line of its own, so it is not money you are quietly counting twice.
Treating savings as an outgoing rather than as leftover money is the one habit that changes budgets. If savings is whatever survives the month, it is usually nothing. If it is a line near the top, the rest of the budget adapts around it.
Checking it against 50/30/20
The common rule of thumb is half your take-home on needs, 30 per cent on wants, 20 per cent on savings and debt. It is a sanity check rather than a law, and it breaks down where housing is expensive — but it is a fast way to see whether one category has quietly taken over.
take home pay 3200 | + | 3,200 |
needs: take home pay * 0.5 | = | 1,600 |
wants: take home pay * 0.3 | = | 960 |
savings: take home pay * 0.2 | = | 640 |
| Total | 3,200 |
Compare these against the budget above: rent, groceries, transport and utilities come to 1,910 against a suggested 1,600, and savings is 400 against a suggested 640. That is the real trade-off, in two numbers.
Bills that are not monthly
Annual car insurance and a quarterly water bill wreck a monthly budget if you only notice them in the month they land. Divide them down and carry them every month instead:
car insurance: -540 / 12 and water: -96 / 3
You are setting aside 45.00 and 32.00 a month for bills that arrive later. This is the single most common reason a budget that looks fine on paper does not survive contact with a real year.
Irregular income
If you are freelance or on variable hours, budget against a figure you can rely on rather than a good month. Take your last six months, use the lowest, and treat anything above it as a surplus to allocate deliberately:
baseline month 2400 then surplus this month 700 as a separate line, so you can see at a glance how much of the month was dependable.
Questions
What is the 50/30/20 budget rule?
Roughly half your take-home pay on needs, 30 per cent on wants, and 20 per cent on savings and debt repayment. It is a rule of thumb rather than a target, and it is hard to hold to in expensive housing markets, but it is a quick way to see whether one category has grown out of proportion.
Should I budget from gross or take-home pay?
Take-home, every time. Gross salary includes money you never see, so budgeting against it builds an error into every line below.
How do I handle annual bills in a monthly budget?
Divide them by twelve and carry the monthly amount every month, so the money is already set aside when the bill arrives. A 540 annual insurance premium is a 45 a month line.
Should savings be a line or whatever is left over?
A line, and preferably near the top. Savings that depend on what survives the month tend to be nothing; savings taken out first make the rest of the budget adapt around them.
Is my financial information stored anywhere?
No. The calculator runs entirely in your browser and there is no server to send anything to. Your sheets are kept in your own browser’s local storage and stay on your device.