Loan repayment simulator: start from what your budget can pay each month and let our calculator show exactly how much that budget can safely buy.
How much would you like to borrow?
Choose the loan amount to estimate your monthly loan payments. Quick, simple and free.
Informative simulation. It is not a loan offer or credit approval.
Most people open a calculator by typing the amount they want. A safer habit is the reverse: decide the repayment your household can carry, then see which amount and term that repayment supports. This guide explains the reverse method, shows the numbers for three budgets and links the result to bank calculators in Australia, Canada and Singapore.
Direct answer: fix a monthly figure that leaves at least ten percent of take-home pay untouched, choose a realistic interest rate and calculate the largest amount that figure repays over each term. At 11% a year, a budget of 400 a month supports roughly 8,600 over two years, 12,200 over three years and 18,400 over five years.
Starting from the budget protects you from a common trap: falling in love with a purchase price and then stretching the term until the repayment looks bearable. The reverse method puts the repayment first, so every option you consider is affordable by design. Whatever the bank later offers, you already know your ceiling.
People often forget that the budget figure must also cover loan fees. An approval fee, a monthly administration charge or optional insurance all compete for exactly the same money as the repayment. If your lender adds ten a month in charges, your simulation should subtract that amount before calculating how much the remaining sum can repay.
The next sections show how to set the budget figure, the reverse formula, a table for three budgets, how the rate changes what you can borrow, how each bank presents its calculator, a worked example for a family, common errors and a set of questions. Keep your take-home pay and fixed monthly bills nearby before you begin.
Setting your repayment ceiling
- Start with your monthly take-home pay.
- Subtract rent or mortgage, utilities, transport, food and insurance.
- Subtract existing debt repayments.
- Keep at least ten percent of take-home pay as a buffer.
- What remains is your maximum repayment, minus any loan fees.
The reverse formula
The usual formula gives a repayment from an amount: P·r/(1−(1+r)^−n). Reversing it gives the amount from a repayment: amount = repayment × (1−(1+r)^−n) / r. With 400 a month at 11% a year, r is about 0.00917. Over 36 months the factor is about 30.5, so 400 supports roughly 12,200.
Three budgets, three terms
| Monthly budget at 11% | 2 years | 3 years | 5 years |
|---|---|---|---|
| 250 | about 5,360 | about 7,640 | about 11,500 |
| 400 | about 8,580 | about 12,220 | about 18,400 |
| 600 | about 12,870 | about 18,330 | about 27,600 |
Longer terms let the same budget borrow more, but the extra comes at a price. Over five years a 400 budget repays 24,000 in total for about 18,400 borrowed; over three years it repays 14,400 for about 12,200. Borrow only what the plan needs, even if the budget could support more.
How the rate changes what you can borrow
| Rate | Amount a 400 budget supports over 3 years |
|---|---|
| 8% | about 12,770 |
| 12% | about 12,040 |
| 18% | about 11,060 |
| 24% | about 10,200 |
A weaker credit profile shrinks the amount your budget can carry. Improving your file before applying can therefore mean borrowing what you need without raising the repayment.
How three banks present their calculators
| Bank | What the calculator shows | What to add yourself |
|---|---|---|
| ANZ (Australia) | Repayment for amount, term and rate | Approval fee and monthly charge |
| BMO (Canada) | Payment for chosen term | Your estimated rate, since rates are personalised |
| UOB (Singapore) | Instalment from the applied rate | EIR and any processing fee |
The guides linked above explain how to read each bank's figures and which costs to add before comparing. Once added, feed the net budget into the reverse method to see the safe amount.
A family example
The Okafor family takes home 6,200 a month. After housing, bills, transport, food and a car loan, about 900 remains. Keeping a 620 buffer leaves 280 for a new loan, minus a 10 monthly fee, so 270. At 11% over three years, that supports about 8,250, enough for the 8,000 kitchen repair they need.
Common errors
- Using gross rather than take-home pay.
- Forgetting irregular costs such as annual insurance.
- Ignoring monthly loan fees.
- Using the lowest advertised rate.
- Borrowing the maximum the budget allows rather than the amount needed.
When income is irregular
Freelancers and commission earners should set the ceiling from a lean month rather than an average one. If a lean month leaves 300 after bills and buffer, use 300 even if good months leave 700. Extra money in strong months can go toward additional repayments, shortening the loan without risking a missed payment during quieter periods.
Combining the reverse method with savings
Sometimes the reverse calculation shows that your budget supports less than the purchase costs. Rather than stretching the term, consider saving the gap first. If you need 10,000 and your budget supports 8,250 over three years, saving the remaining 1,750 over a few months may cost far less than borrowing it for five years.
| Option | What happens | Trade-off |
|---|---|---|
| Save the gap first | Borrow only what the budget supports | Purchase delayed by a few months |
| Extend the term | Borrow the full amount | More interest in total |
| Raise the budget | Cut other spending | Less flexibility each month |
Reviewing the ceiling over time
Your ceiling is not permanent. Recalculate it after a pay rise, a change in rent or the end of another loan. A higher ceiling can allow overpayments that finish the loan sooner, while a lower one is an early signal to contact the lender before any repayment is missed.
Using the simulator on this page
Enter the amount from your reverse calculation and check that the repayment matches your ceiling. Then try one year less. If the repayment still fits, take the shorter term and save interest. If not, keep your original choice and plan extra payments when income allows.
The Okafor family rerun the reverse calculation every year when their pay changes, which shows them how much extra they can safely put toward the loan.
Summary: budget first, amount second
Starting from the repayment you can afford makes every option safe by design and keeps borrowing aligned with real needs.
- Set a ceiling that leaves a ten percent buffer.
- Subtract loan fees from the budget.
- Use the reverse formula for each term.
- Test several rates.
- Borrow what the plan needs, not the maximum.
Frequently asked questions
Why not just ask the bank how much I can borrow?
Banks calculate what they can lend, which may exceed what you can comfortably repay.
What buffer is enough?
Ten percent of take-home pay is a sensible minimum, more if your income varies.
Does the reverse method work for flat-rate loans?
Yes, once you convert the flat rate into an effective rate.
Can I use it for credit cards?
It works for any fixed repayment plan, including a payoff plan for a card balance.
Should the buffer be larger for families?
Often yes, because children bring irregular costs, so many families keep fifteen percent or more aside.
What if my ceiling is zero?
Then a new loan would strain your finances, so focus on reducing costs or existing debt before borrowing.
Does the method work for car loans?
Yes, any fixed instalment loan can be planned this way, including secured car loans.
Conclusion
A loan repayment simulator used in reverse keeps your borrowing inside your budget. Set your ceiling, subtract fees, calculate the supported amount and compare bank calculators from ANZ, BMO and UOB through the guides linked above before you apply.