How the Budget Calculator Works
How the Budget Calculator Works
A budget is a plan for your money. It shows how much comes in each month, how much goes out, and what is left. Many people are surprised by where their money goes. The Budget Calculator adds up your income and spending, shows the shares, and compares them with a well-known guideline, the 50/30/20 rule.
What you enter
- Monthly income after tax: your take-home pay, plus any other income, such as a partner's pay or side work. Use the amount that reaches your account, not your salary before tax.
- Needs: the costs you must pay. That is rent or a mortgage, utilities, groceries, transport, insurance, the minimum payments on your debts, and childcare or education.
- Wants: spending that you choose. That is eating out and entertainment, subscriptions and hobbies, shopping and personal care, and everything else.
- Savings and investing: money you set aside, such as an emergency fund, retirement, and extra payments on debt.
- Emergency savings so far (optional): to show how many months of needs it would cover.
How the results are worked out
left over = income - (needs + wants + savings) share of income = amount / income x 100 savings rate = savings / income x 100
If the result is positive, you plan to spend less than you earn, and there is money left to use. If it is negative, you are overspending, and you would have to use savings or borrow to make up the difference.
The 50/30/20 rule
The 50/30/20 rule is a simple guideline for splitting your take-home pay:
| Group | Share of take-home pay | What it covers |
|---|---|---|
| Needs | 50% | Housing, food, transport, insurance, minimum debt payments |
| Wants | 30% | Dining out, entertainment, hobbies, shopping |
| Savings | 20% | Emergency fund, retirement, extra debt payments |
- Group: Needs
Share of take-home pay: 50%
What it covers: Housing, food, transport, insurance, minimum debt payments - Group: Wants
Share of take-home pay: 30%
What it covers: Dining out, entertainment, hobbies, shopping - Group: Savings
Share of take-home pay: 20%
What it covers: Emergency fund, retirement, extra debt payments
It is a rule of thumb, not a law. In a costly city, needs may take much more than half. That is fine, as long as you know it, and plan for it. The calculator shows the gap in dollars for each group, so you can see where you are above or below the guide.
A worked example
Your take-home pay is $4,500 a month.
| Group | Spending | Share of income | Guideline | Difference |
|---|---|---|---|---|
| Needs (rent $1,400, utilities $250, groceries $550, transport $400, insurance $250, debts $250) | $3,100 | 68.9% | $2,250 (50%) | +$850 |
| Wants (dining $300, subscriptions $100, shopping $250, other $150) | $800 | 17.8% | $1,350 (30%) | -$550 |
| Savings | $400 | 8.9% | $900 (20%) | -$500 |
- Group: Needs (rent $1,400, utilities $250, groceries $550, transport $400, insurance $250, debts $250)
Spending: $3,100
Share of income: 68.9%
Guideline: $2,250 (50%)
Difference: +$850 - Group: Wants (dining $300, subscriptions $100, shopping $250, other $150)
Spending: $800
Share of income: 17.8%
Guideline: $1,350 (30%)
Difference: -$550 - Group: Savings
Spending: $400
Share of income: 8.9%
Guideline: $900 (20%)
Difference: -$500
Total spending and saving is $4,300, so $200 is left over each month, which is $2,400 a year. The needs are well above the guideline, and the savings rate is below 20%. That does not mean the budget is wrong. It shows that housing and other must-pay costs take a big share, so growing savings may need more income, or lower costs. An emergency fund of $3,000 covers about 1 month of needs.
Chart: where the income goes
Needs ████████████████████████████████████████ 68.9% $3,100 Wants ██████████ 17.8% $800 Savings █████ 8.9% $400 Left over ███ 4.4% $200
How to use the results
- If you are overspending, start with the wants. Small cuts to several categories are easier to keep than one big cut.
- If you have money left over, give it a job before it disappears: build an emergency fund, pay down debt with a high interest rate, or invest for the long term.
- If your needs are very high, look at the largest ones: housing, transport and debt. Changes there matter most.
- Aim for an emergency fund of about 3 to 6 months of needs. The calculator shows how many months yours covers.
- Check your budget against your real spending. Your bank statements show what you actually spend.
What this calculator does not include
- Irregular costs, such as yearly bills, car repairs and holidays. Spread them out and add a monthly share.
- Changes in income or spending from month to month.
- Taxes. Enter income after tax.
This tool gives an estimate for general information only. It is not financial advice. Your own goals and situation should guide your budget.