Loan Affordability Calculator
This calculator works backwards from a monthly payment you can afford to the maximum principal it would support. Enter your own payment, rate, and term — the defaults are examples, not an offer.
How this calculator works
Affordability is the reverse of a payment calculation. Instead of asking what a loan costs each month, you start with the payment your budget can carry and solve for the principal.
Formula: maxPrincipal = payment × (1 − (1 + r)^−n) ÷ r, where r = annualRatePct ÷ 100 ÷ 12 and n is the term in months. When the rate is 0%, the principal is simply payment × n.
A longer term raises the amount you can borrow for the same payment, because the cost is spread over more months. The trade-off is more total interest. A higher rate lowers the amount you can borrow for the same payment.
Lenders do not decide affordability from the payment alone. They look at your income, your existing debts, your credit history, and your debt-to-income ratio. A lender may approve less than this calculator suggests, or decline entirely. Treat the result as a planning figure, not an approval.
Before borrowing the maximum, stress-test the payment. Ask what happens if your income falls or rates rise on a variable product, and keep an emergency buffer. Borrowing the most you can afford leaves no room for a surprise.
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Frequently Asked Questions
Does this show what a lender will approve?
No. It shows the principal that a given payment would support at a given rate and term. A lender also assesses income, existing debts, and credit history.
Why does a longer term let me borrow more?
The same payment is spread over more months, so it supports a larger principal. You pay more interest in total.
Should I borrow the maximum?
Usually not. Leaving room in your budget protects you if your income changes or an unexpected cost appears.
How is affordability usually assessed?
Lenders compare your total debt payments with your income. A common guideline is to keep total debt payments below about 40% of gross income, but each lender sets its own rule.
Last updated: September 16, 2026 · By the Instalment.ca Editorial Team
We research Canadian lending rules and update these pages when the law, the data, or the available offers change. We are not a lender and we do not provide personal financial advice.
Instalment.ca is a loan matching and comparison service, not a lender.
We may earn a commission when you click or apply through our links.
This is general information, not financial, legal, or tax advice.
Rates and terms vary by lender, creditworthiness, and province. Figures shown are examples only.